DATAMONGO-1598 - Release version 1.10.1 (Ingalls SR1).

Remove additional quoting around JSON serialization because JSON serialization adds quotes to a string. Reformat code.

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,9 +1,12 @@
+<!--
+
 Thank you for proposing a pull request. This template will guide you through the essential steps necessary for a pull request.
 Make sure that:
 
+-->
+
 - [ ] You have read the [Spring Data contribution guidelines](https://github.com/spring-projects/spring-data-build/blob/master/CONTRIBUTING.adoc).
 - [ ] There is a ticket in the bug tracker for the project in our [JIRA](https://jira.spring.io/browse/DATAMONGO).
 - [ ] You use the code formatters provided [here](https://github.com/spring-projects/spring-data-build/tree/master/etc/ide) and have them applied to your changes. Don’t submit any formatting related changes.
 - [ ] You submit test cases (unit or integration tests) that back your changes.
 - [ ] You added yourself as author in the headers of the classes you touched. Amend the date range in the Apache license header if needed. For new types, add the license header (copy from another file and set the current year only).
-- [ ] You provide your full name and an email address registered with your GitHub account. If you’re a first-time submitter, make sure you have completed the [Contributor’s License Agreement form](https://support.springsource.com/spring_committer_signup).

.travis.yml

@@ -9,11 +9,13 @@ before_script:
 env:
   matrix:
     - PROFILE=ci
+    - PROFILE=mongo-next
     - PROFILE=mongo3
     - PROFILE=mongo3-next
     - PROFILE=mongo31
     - PROFILE=mongo32
     - PROFILE=mongo33
+    - PROFILE=mongo34
     - PROFILE=mongo34-next
 
 # Current MongoDB version is 2.4.2 as of 2016-04, see https://github.com/travis-ci/travis-ci/issues/3694
@@ -21,10 +23,11 @@ env:
 addons:
   apt:
     sources:
-    - mongodb-3.2-precise
+    - mongodb-3.4-precise
     packages:
     - mongodb-org-server
     - mongodb-org-shell
+    - oracle-java8-installer
 
 sudo: false
 

README.md

@@ -143,8 +143,8 @@ public class MyService {
 Here are some ways for you to get involved in the community:
 
 * Get involved with the Spring community on Stackoverflow and help out on the [spring-data-mongodb](http://stackoverflow.com/questions/tagged/spring-data-mongodb) tag by responding to questions and joining the debate.
-* Create [JIRA](https://jira.springframework.org/browse/DATADOC) tickets for bugs and new features and comment and vote on the ones that you are interested in.  
+* Create [JIRA](https://jira.spring.io/browse/DATAMONGO) tickets for bugs and new features and comment and vote on the ones that you are interested in.  
 * Github is for social coding: if you want to write code, we encourage contributions through pull requests from [forks of this repository](http://help.github.com/forking/). If you want to contribute code this way, please reference a JIRA ticket as well covering the specific issue you are addressing.
 * Watch for upcoming articles on Spring by [subscribing](http://spring.io/blog) to spring.io.
 
-Before we accept a non-trivial patch or pull request we will need you to sign the [contributor's agreement](https://support.springsource.com/spring_committer_signup).  Signing the contributor's agreement does not grant anyone commit rights to the main repository, but it does mean that we can accept your contributions, and you will get an author credit if we do.  Active contributors might be asked to join the core team, and given the ability to merge pull requests.
+Before we accept a non-trivial patch or pull request we will need you to [sign the Contributor License Agreement](https://cla.pivotal.io/sign/spring). Signing the contributor’s agreement does not grant anyone commit rights to the main repository, but it does mean that we can accept your contributions, and you will get an author credit if we do. If you forget to do so, you'll be reminded when you submit a pull request. Active contributors might be asked to join the core team, and given the ability to merge pull requests.

pom.xml

@@ -5,7 +5,7 @@
 
 	<groupId>org.springframework.data</groupId>
 	<artifactId>spring-data-mongodb-parent</artifactId>
-	<version>2.0.0.M1</version>
+	<version>1.10.1.RELEASE</version>
 	<packaging>pom</packaging>
 
 	<name>Spring Data MongoDB</name>
@@ -15,7 +15,7 @@
 	<parent>
 		<groupId>org.springframework.data.build</groupId>
 		<artifactId>spring-data-parent</artifactId>
-		<version>2.0.0.M1</version>
+		<version>1.9.1.RELEASE</version>
 	</parent>
 
 	<modules>
@@ -28,9 +28,9 @@
 	<properties>
 		<project.type>multi</project.type>
 		<dist.id>spring-data-mongodb</dist.id>
-		<springdata.commons>2.0.0.M1</springdata.commons>
-		<mongo>3.2.2</mongo>
-		<mongo.reactivestreams>1.2.0</mongo.reactivestreams>
+		<springdata.commons>1.13.1.RELEASE</springdata.commons>
+		<mongo>2.14.3</mongo>
+		<mongo.osgi>2.13.0</mongo.osgi>
 	</properties>
 
 	<developers>
@@ -100,20 +100,25 @@
 			</roles>
 			<timezone>+1</timezone>
 		</developer>
-		<developer>
-			<id>mpaluch</id>
-			<name>Mark Paluch</name>
-			<email>mpaluch at pivotal.io</email>
-			<organization>Pivotal</organization>
-			<organizationUrl>http://www.pivotal.io</organizationUrl>
-			<roles>
-				<role>Developer</role>
-			</roles>
-			<timezone>+1</timezone>
-		</developer>
 	</developers>
 
 	<profiles>
+		<profile>
+
+			<id>mongo-next</id>
+			<properties>
+				<mongo>2.15.0-SNAPSHOT</mongo>
+			</properties>
+
+			<repositories>
+				<repository>
+					<id>mongo-snapshots</id>
+					<url>https://oss.sonatype.org/content/repositories/snapshots</url>
+				</repository>
+			</repositories>
+
+		</profile>
+
 		<profile>
 
 			<id>mongo3</id>
@@ -173,11 +178,20 @@
 
 		</profile>
 
+		<profile>
+
+			<id>mongo34</id>
+			<properties>
+				<mongo>3.4.0</mongo>
+			</properties>
+
+		</profile>
+
 		<profile>
 
 			<id>mongo34-next</id>
 			<properties>
-				<mongo>3.4.0-SNAPSHOT</mongo>
+				<mongo>3.4.1-SNAPSHOT</mongo>
 			</properties>
 
 			<repositories>
@@ -215,8 +229,8 @@
 
 	<repositories>
 		<repository>
-			<id>spring-libs-milestone</id>
-			<url>https://repo.spring.io/libs-milestone</url>
+			<id>spring-libs-release</id>
+			<url>https://repo.spring.io/libs-release</url>
 		</repository>
 	</repositories>
 

spring-data-mongodb-cross-store/pom.xml

@@ -6,7 +6,7 @@
 	<parent>
 		<groupId>org.springframework.data</groupId>
 		<artifactId>spring-data-mongodb-parent</artifactId>
-		<version>2.0.0.M1</version>
+		<version>1.10.1.RELEASE</version>
 		<relativePath>../pom.xml</relativePath>
 	</parent>
 
@@ -14,8 +14,8 @@
 	<name>Spring Data MongoDB - Cross-Store Support</name>
 
 	<properties>
-		<jpa>2.1.1</jpa>
-		<hibernate>5.2.1.Final</hibernate>
+		<jpa>2.0.0</jpa>
+		<hibernate>3.6.10.Final</hibernate>
 	</properties>
 
 	<dependencies>
@@ -48,15 +48,7 @@
 		<dependency>
 			<groupId>org.springframework.data</groupId>
 			<artifactId>spring-data-mongodb</artifactId>
-			<version>2.0.0.M1</version>
-		</dependency>
-
-		<!-- reactive -->
-		<dependency>
-		 	<groupId>io.projectreactor</groupId>
-			<artifactId>reactor-core</artifactId>
-			<version>${reactor}</version>
-			<optional>true</optional>
+			<version>1.10.1.RELEASE</version>
 		</dependency>
 
 		<dependency>
@@ -95,7 +87,7 @@
 		<dependency>
 			<groupId>org.hibernate</groupId>
 			<artifactId>hibernate-validator</artifactId>
-			<version>5.2.4.Final</version>
+			<version>4.0.2.GA</version>
 			<scope>test</scope>
 		</dependency>
 

spring-data-mongodb-cross-store/src/main/java/org/springframework/data/mongodb/crossstore/MongoChangeSetPersister.java

@@ -17,7 +17,6 @@ package org.springframework.data.mongodb.crossstore;
 
 import javax.persistence.EntityManagerFactory;
 
-import org.bson.Document;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.springframework.dao.DataAccessException;
@@ -30,10 +29,10 @@ import org.springframework.data.mongodb.core.CollectionCallback;
 import org.springframework.data.mongodb.core.MongoTemplate;
 import org.springframework.util.ClassUtils;
 
+import com.mongodb.BasicDBObject;
+import com.mongodb.DBCollection;
+import com.mongodb.DBObject;
 import com.mongodb.MongoException;
-import com.mongodb.client.MongoCollection;
-import com.mongodb.client.model.Filters;
-import com.mongodb.client.result.DeleteResult;
 
 /**
  * @author Thomas Risberg
@@ -75,15 +74,15 @@ public class MongoChangeSetPersister implements ChangeSetPersister<Object> {
 
 		String collName = getCollectionNameForEntity(entityClass);
 
-		final Document dbk = new Document();
+		final DBObject dbk = new BasicDBObject();
 		dbk.put(ENTITY_ID, id);
 		dbk.put(ENTITY_CLASS, entityClass.getName());
 		if (log.isDebugEnabled()) {
 			log.debug("Loading MongoDB data for {}", dbk);
 		}
 		mongoTemplate.execute(collName, new CollectionCallback<Object>() {
-			public Object doInCollection(MongoCollection<Document> collection) throws MongoException, DataAccessException {
-				for (Document dbo : collection.find(dbk)) {
+			public Object doInCollection(DBCollection collection) throws MongoException, DataAccessException {
+				for (DBObject dbo : collection.find(dbk)) {
 					String key = (String) dbo.get(ENTITY_FIELD_NAME);
 					if (log.isDebugEnabled()) {
 						log.debug("Processing key: {}", key);
@@ -144,31 +143,27 @@ public class MongoChangeSetPersister implements ChangeSetPersister<Object> {
 		for (String key : cs.getValues().keySet()) {
 			if (key != null && !key.startsWith("_") && !key.equals(ChangeSetPersister.ID_KEY)) {
 				Object value = cs.getValues().get(key);
-				final Document dbQuery = new Document();
+				final DBObject dbQuery = new BasicDBObject();
 				dbQuery.put(ENTITY_ID, getPersistentId(entity, cs));
 				dbQuery.put(ENTITY_CLASS, entity.getClass().getName());
 				dbQuery.put(ENTITY_FIELD_NAME, key);
-				final Document dbId = mongoTemplate.execute(collName, new CollectionCallback<Document>() {
-					public Document doInCollection(MongoCollection<Document> collection)
-							throws MongoException, DataAccessException {
-						Document id = collection.find(dbQuery).first();
-						return id;
+				DBObject dbId = mongoTemplate.execute(collName, new CollectionCallback<DBObject>() {
+					public DBObject doInCollection(DBCollection collection) throws MongoException, DataAccessException {
+						return collection.findOne(dbQuery);
 					}
 				});
-
 				if (value == null) {
 					if (log.isDebugEnabled()) {
 						log.debug("Flush: removing: {}", dbQuery);
 					}
 					mongoTemplate.execute(collName, new CollectionCallback<Object>() {
-						public Object doInCollection(MongoCollection<Document> collection)
-								throws MongoException, DataAccessException {
-							DeleteResult dr = collection.deleteMany(dbQuery);
+						public Object doInCollection(DBCollection collection) throws MongoException, DataAccessException {
+							collection.remove(dbQuery);
 							return null;
 						}
 					});
 				} else {
-					final Document dbDoc = new Document();
+					final DBObject dbDoc = new BasicDBObject();
 					dbDoc.putAll(dbQuery);
 					if (log.isDebugEnabled()) {
 						log.debug("Flush: saving: {}", dbQuery);
@@ -179,18 +174,8 @@ public class MongoChangeSetPersister implements ChangeSetPersister<Object> {
 						dbDoc.put("_id", dbId.get("_id"));
 					}
 					mongoTemplate.execute(collName, new CollectionCallback<Object>() {
-						public Object doInCollection(MongoCollection<Document> collection)
-								throws MongoException, DataAccessException {
-
-							if (dbId != null) {
-								collection.replaceOne(Filters.eq("_id", dbId.get("_id")), dbDoc);
-							} else {
-
-								if (dbDoc.containsKey("_id") && dbDoc.get("_id") == null) {
-									dbDoc.remove("_id");
-								}
-								collection.insertOne(dbDoc);
-							}
+						public Object doInCollection(DBCollection collection) throws MongoException, DataAccessException {
+							collection.save(dbDoc);
 							return null;
 						}
 					});

spring-data-mongodb-cross-store/src/test/java/org/springframework/data/mongodb/crossstore/CrossStoreMongoTests.java

@@ -18,7 +18,6 @@ package org.springframework.data.mongodb.crossstore;
 import javax.persistence.EntityManager;
 import javax.persistence.PersistenceContext;
 
-import org.bson.Document;
 import org.junit.After;
 import org.junit.Assert;
 import org.junit.Before;
@@ -37,6 +36,8 @@ import org.springframework.transaction.annotation.Transactional;
 import org.springframework.transaction.support.TransactionCallback;
 import org.springframework.transaction.support.TransactionTemplate;
 
+import com.mongodb.DBObject;
+
 /**
  * Integration tests for MongoDB cross-store persistence (mainly {@link MongoChangeSetPersister}).
  * 
@@ -47,11 +48,14 @@ import org.springframework.transaction.support.TransactionTemplate;
 @ContextConfiguration("classpath:/META-INF/spring/applicationContext.xml")
 public class CrossStoreMongoTests {
 
-	@Autowired MongoTemplate mongoTemplate;
+	@Autowired
+	MongoTemplate mongoTemplate;
 
-	@PersistenceContext EntityManager entityManager;
+	@PersistenceContext
+	EntityManager entityManager;
 
-	@Autowired PlatformTransactionManager transactionManager;
+	@Autowired
+	PlatformTransactionManager transactionManager;
 	TransactionTemplate txTemplate;
 
 	@Before
@@ -183,7 +187,7 @@ public class CrossStoreMongoTests {
 
 		boolean weFound3 = false;
 
-		for (Document dbo : this.mongoTemplate.getCollection(mongoTemplate.getCollectionName(Person.class)).find()) {
+		for (DBObject dbo : this.mongoTemplate.getCollection(mongoTemplate.getCollectionName(Person.class)).find()) {
 			Assert.assertTrue(!dbo.get("_entity_id").equals(2L));
 			if (dbo.get("_entity_id").equals(3L)) {
 				weFound3 = true;

spring-data-mongodb-cross-store/src/test/resources/META-INF/spring/applicationContext.xml

@@ -20,7 +20,7 @@
   <mongo:mapping-converter/>
   
   <!--  Mongo config -->
-  <bean id="mongo" class="org.springframework.data.mongodb.core.MongoClientFactoryBean">
+  <bean id="mongo" class="org.springframework.data.mongodb.core.MongoFactoryBean">
     <property name="host" value="localhost"/>
     <property name="port" value="27017"/>
   </bean>

spring-data-mongodb-cross-store/template.mf

@@ -0,0 +1,18 @@
+Bundle-SymbolicName: org.springframework.data.mongodb.crossstore
+Bundle-Name: Spring Data MongoDB Cross Store Support
+Bundle-Vendor: Pivotal Software, Inc.
+Bundle-ManifestVersion: 2
+Import-Package:
+ sun.reflect;version="0";resolution:=optional
+Export-Template:
+ org.springframework.data.mongodb.crossstore.*;version="${project.version}"
+Import-Template:
+ com.mongodb.*;version="${mongo.osgi:[=.=.=,+1.0.0)}",
+ javax.persistence.*;version="${jpa:[=.=.=,+1.0.0)}",
+ org.aspectj.*;version="${aspectj:[1.0.0, 2.0.0)}",
+ org.bson.*;version="0",
+ org.slf4j.*;version="${slf4j:[=.=.=,+1.0.0)}",
+ org.springframework.*;version="${spring:[=.=.=.=,+1.0.0)}",
+ org.springframework.data.*;version="${springdata.commons:[=.=.=.=,+1.0.0)}",
+ org.springframework.data.mongodb.*;version="${project.version:[=.=.=.=,+1.0.0)}",
+ org.w3c.dom.*;version="0"

spring-data-mongodb-distribution/pom.xml

@@ -13,7 +13,7 @@
 	<parent>
 		<groupId>org.springframework.data</groupId>
 		<artifactId>spring-data-mongodb-parent</artifactId>
-		<version>2.0.0.M1</version>
+		<version>1.10.1.RELEASE</version>
 		<relativePath>../pom.xml</relativePath>
 	</parent>
 

spring-data-mongodb-log4j/pom.xml

@@ -5,7 +5,7 @@
 	<parent>
 		<groupId>org.springframework.data</groupId>
 		<artifactId>spring-data-mongodb-parent</artifactId>
-		<version>2.0.0.M1</version>
+		<version>1.10.1.RELEASE</version>
 		<relativePath>../pom.xml</relativePath>
 	</parent>
 

spring-data-mongodb-log4j/src/main/java/org/springframework/data/mongodb/log4j/MongoLog4jAppender.java

@@ -18,6 +18,8 @@ package org.springframework.data.mongodb.log4j;
 import java.net.UnknownHostException;
 import java.util.Arrays;
 import java.util.Calendar;
+import java.util.Collections;
+import java.util.List;
 import java.util.Map;
 
 import org.apache.log4j.AppenderSkeleton;
@@ -31,14 +33,17 @@ import com.mongodb.BasicDBObject;
 import com.mongodb.DB;
 import com.mongodb.Mongo;
 import com.mongodb.MongoClient;
+import com.mongodb.MongoCredential;
+import com.mongodb.ServerAddress;
 import com.mongodb.WriteConcern;
 
 /**
  * Log4j appender writing log entries into a MongoDB instance.
- * 
+ *
  * @author Jon Brisbin
  * @author Oliver Gierke
- * @auhtor Christoph Strobl
+ * @author Christoph Strobl
+ * @author Ricardo Espirito Santo
  */
 public class MongoLog4jAppender extends AppenderSkeleton {
 
@@ -56,6 +61,9 @@ public class MongoLog4jAppender extends AppenderSkeleton {
 
 	protected String host = "localhost";
 	protected int port = 27017;
+	protected String username;
+	protected String password;
+	protected String authenticationDatabase;
 	protected String database = "logs";
 	protected String collectionPattern = "%c";
 	protected PatternLayout collectionLayout = new PatternLayout(collectionPattern);
@@ -65,8 +73,7 @@ public class MongoLog4jAppender extends AppenderSkeleton {
 	protected Mongo mongo;
 	protected DB db;
 
-	public MongoLog4jAppender() {
-	}
+	public MongoLog4jAppender() {}
 
 	public MongoLog4jAppender(boolean isActive) {
 		super(isActive);
@@ -88,6 +95,53 @@ public class MongoLog4jAppender extends AppenderSkeleton {
 		this.port = port;
 	}
 
+	/**
+	 * @return
+	 * @since 1.10
+	 */
+	public String getUsername() {
+		return username;
+	}
+
+	/**
+	 * @param username may be {@literal null} for unauthenticated access.
+	 * @since 1.10
+	 */
+	public void setUsername(String username) {
+		this.username = username;
+	}
+
+	/**
+	 * @return
+	 * @since 1.10
+	 */
+	public String getPassword() {
+		return password;
+	}
+
+	/**
+	 * @param password may be {@literal null} for unauthenticated access.
+	 * @since 1.10
+	 */
+	public void setPassword(String password) {
+		this.password = password;
+	}
+
+	/**
+	 * @return
+	 */
+	public String getAuthenticationDatabase() {
+		return authenticationDatabase;
+	}
+
+	/**
+	 * @param authenticationDatabase may be {@literal null} to use {@link #getDatabase()} as authentication database.
+	 * @since 1.10
+	 */
+	public void setAuthenticationDatabase(String authenticationDatabase) {
+		this.authenticationDatabase = authenticationDatabase;
+	}
+
 	public String getDatabase() {
 		return database;
 	}
@@ -113,14 +167,14 @@ public class MongoLog4jAppender extends AppenderSkeleton {
 		this.applicationId = applicationId;
 	}
 
-	public void setWarnOrHigherWriteConcern(String wc) {
-		this.warnOrHigherWriteConcern = WriteConcern.valueOf(wc);
-	}
-
 	public String getWarnOrHigherWriteConcern() {
 		return warnOrHigherWriteConcern.toString();
 	}
 
+	public void setWarnOrHigherWriteConcern(String wc) {
+		this.warnOrHigherWriteConcern = WriteConcern.valueOf(wc);
+	}
+
 	public String getInfoOrLowerWriteConcern() {
 		return infoOrLowerWriteConcern.toString();
 	}
@@ -130,10 +184,26 @@ public class MongoLog4jAppender extends AppenderSkeleton {
 	}
 
 	protected void connectToMongo() throws UnknownHostException {
-		this.mongo = new MongoClient(host, port);
+
+		this.mongo = createMongoClient();
 		this.db = mongo.getDB(database);
 	}
 
+	private MongoClient createMongoClient() throws UnknownHostException {
+
+		ServerAddress serverAddress = new ServerAddress(host, port);
+
+		if (null == password || null == username) {
+			return new MongoClient(serverAddress);
+		}
+
+		String authenticationDatabaseToUse = authenticationDatabase == null ? this.database : authenticationDatabase;
+		MongoCredential mongoCredential = MongoCredential.createCredential(username,
+				authenticationDatabaseToUse, password.toCharArray());
+		List<MongoCredential> credentials = Collections.singletonList(mongoCredential);
+		return new MongoClient(serverAddress, credentials);
+	}
+
 	/*
 	 * (non-Javadoc)
 	 * @see org.apache.log4j.AppenderSkeleton#append(org.apache.log4j.spi.LoggingEvent)

spring-data-mongodb-log4j/src/test/java/org/springframework/data/mongodb/log4j/MongoLog4jAppenderAuthenticationIntegrationTests.java

@@ -0,0 +1,114 @@
+/*
+ * Copyright 2016 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb.log4j;
+
+import static org.hamcrest.Matchers.*;
+import static org.junit.Assert.*;
+
+import java.util.Calendar;
+import java.util.Collections;
+
+import org.apache.log4j.LogManager;
+import org.apache.log4j.Logger;
+import org.apache.log4j.MDC;
+import org.apache.log4j.PropertyConfigurator;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import com.mongodb.BasicDBList;
+import com.mongodb.BasicDBObject;
+import com.mongodb.BasicDBObjectBuilder;
+import com.mongodb.DB;
+import com.mongodb.DBCursor;
+import com.mongodb.MongoClient;
+import com.mongodb.MongoCredential;
+import com.mongodb.ServerAddress;
+
+/**
+ * Integration tests for {@link MongoLog4jAppender} using authentication.
+ *
+ * @author Mark Paluch
+ */
+public class MongoLog4jAppenderAuthenticationIntegrationTests {
+
+	private final static String username = "admin";
+	private final static String password = "test";
+	private final static String authenticationDatabase = "logs";
+
+	MongoClient mongo;
+	DB db;
+	String collection;
+	ServerAddress serverLocation;
+
+	Logger log;
+
+	@Before
+	public void setUp() throws Exception {
+
+		serverLocation = new ServerAddress("localhost", 27017);
+
+		mongo = new MongoClient(serverLocation);
+		db = mongo.getDB("logs");
+
+		BasicDBList roles = new BasicDBList();
+		roles.add("dbOwner");
+		db.command(new BasicDBObjectBuilder().add("createUser", username).add("pwd", password).add("roles", roles).get());
+		mongo.close();
+
+		mongo = new MongoClient(serverLocation, Collections
+				.singletonList(MongoCredential.createCredential(username, authenticationDatabase, password.toCharArray())));
+		db = mongo.getDB("logs");
+
+		Calendar now = Calendar.getInstance();
+		collection = String.valueOf(now.get(Calendar.YEAR)) + String.format("%1$02d", now.get(Calendar.MONTH) + 1);
+
+		LogManager.resetConfiguration();
+		PropertyConfigurator.configure(getClass().getResource("/log4j-with-authentication.properties"));
+
+		log = Logger.getLogger(MongoLog4jAppenderIntegrationTests.class.getName());
+	}
+
+	@After
+	public void tearDown() {
+
+		if (db != null) {
+			db.getCollection(collection).remove(new BasicDBObject());
+			db.command(new BasicDBObject("dropUser", username));
+		}
+
+		LogManager.resetConfiguration();
+		PropertyConfigurator.configure(getClass().getResource("/log4j.properties"));
+	}
+
+	@Test
+	public void testLogging() {
+
+		log.debug("DEBUG message");
+		log.info("INFO message");
+		log.warn("WARN message");
+		log.error("ERROR message");
+
+		DBCursor msgs = db.getCollection(collection).find();
+		assertThat(msgs.count(), is(4));
+	}
+
+	@Test
+	public void testProperties() {
+		MDC.put("property", "one");
+		log.debug("DEBUG message");
+	}
+}

spring-data-mongodb-log4j/src/test/java/org/springframework/data/mongodb/log4j/MongoLog4jAppenderIntegrationTests.java

@@ -20,8 +20,10 @@ import static org.junit.Assert.*;
 
 import java.util.Calendar;
 
+import org.apache.log4j.LogManager;
 import org.apache.log4j.Logger;
 import org.apache.log4j.MDC;
+import org.apache.log4j.PropertyConfigurator;
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;
@@ -30,31 +32,34 @@ import com.mongodb.BasicDBObject;
 import com.mongodb.DB;
 import com.mongodb.DBCursor;
 import com.mongodb.MongoClient;
+import com.mongodb.ServerAddress;
 
 /**
  * Integration tests for {@link MongoLog4jAppender}.
- * 
+ *
  * @author Jon Brisbin
  * @author Oliver Gierke
  * @author Christoph Strobl
  */
 public class MongoLog4jAppenderIntegrationTests {
 
-	static final String NAME = MongoLog4jAppenderIntegrationTests.class.getName();
-
-	private static final Logger log = Logger.getLogger(NAME);
 	MongoClient mongo;
 	DB db;
 	String collection;
+	ServerAddress serverLocation;
+	Logger log;
 
 	@Before
 	public void setUp() throws Exception {
+		serverLocation = new ServerAddress("localhost", 27017);
 
-		mongo = new MongoClient("localhost", 27017);
+		mongo = new MongoClient(serverLocation);
 		db = mongo.getDB("logs");
 
 		Calendar now = Calendar.getInstance();
 		collection = String.valueOf(now.get(Calendar.YEAR)) + String.format("%1$02d", now.get(Calendar.MONTH) + 1);
+
+		log = Logger.getLogger(MongoLog4jAppenderIntegrationTests.class.getName());
 	}
 
 	@After
@@ -76,7 +81,6 @@ public class MongoLog4jAppenderIntegrationTests {
 
 	@Test
 	public void testProperties() {
-
 		MDC.put("property", "one");
 		log.debug("DEBUG message");
 	}

spring-data-mongodb-log4j/src/test/java/org/springframework/data/mongodb/log4j/MongoLog4jAppenderUnitTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013 the original author or authors.
+ * Copyright 2013-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -24,10 +24,7 @@ import org.junit.Test;
  */
 public class MongoLog4jAppenderUnitTests {
 
-	/**
-	 * @see DATAMONGO-641
-	 */
-	@Test
+	@Test // DATAMONGO-641
 	public void closesWithoutMongoInstancePresent() {
 		new MongoLog4jAppender().close();
 	}

spring-data-mongodb-log4j/src/test/resources/log4j-with-authentication.properties

@@ -0,0 +1,16 @@
+log4j.rootCategory=INFO, mongo
+
+log4j.appender.mongo=org.springframework.data.mongodb.log4j.MongoLog4jAppender
+log4j.appender.mongo.layout=org.apache.log4j.PatternLayout
+log4j.appender.mongo.layout.ConversionPattern=%d %p [%c] - <%m>%n
+log4j.appender.mongo.host = localhost
+log4j.appender.mongo.port = 27017
+log4j.appender.mongo.database = logs
+log4j.appender.mongo.username = admin
+log4j.appender.mongo.password = test
+log4j.appender.mongo.authenticationDatabase = logs
+log4j.appender.mongo.collectionPattern = %X{year}%X{month}
+log4j.appender.mongo.applicationId = my.application
+log4j.appender.mongo.warnOrHigherWriteConcern = FSYNC_SAFE
+
+log4j.category.org.springframework.data.mongodb=DEBUG

spring-data-mongodb-log4j/src/test/resources/log4j.properties

@@ -1,13 +1,13 @@
-log4j.rootCategory=INFO, stdout
+log4j.rootCategory=INFO, mongo
 
-log4j.appender.stdout=org.springframework.data.mongodb.log4j.MongoLog4jAppender
-log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
-log4j.appender.stdout.layout.ConversionPattern=%d %p [%c] - <%m>%n
-log4j.appender.stdout.host = localhost
-log4j.appender.stdout.port = 27017
-log4j.appender.stdout.database = logs
-log4j.appender.stdout.collectionPattern = %X{year}%X{month}
-log4j.appender.stdout.applicationId = my.application
-log4j.appender.stdout.warnOrHigherWriteConcern = FSYNC_SAFE
+log4j.appender.mongo=org.springframework.data.mongodb.log4j.MongoLog4jAppender
+log4j.appender.mongo.layout=org.apache.log4j.PatternLayout
+log4j.appender.mongo.layout.ConversionPattern=%d %p [%c] - <%m>%n
+log4j.appender.mongo.host = localhost
+log4j.appender.mongo.port = 27017
+log4j.appender.mongo.database = logs
+log4j.appender.mongo.collectionPattern = %X{year}%X{month}
+log4j.appender.mongo.applicationId = my.application
+log4j.appender.mongo.warnOrHigherWriteConcern = FSYNC_SAFE
 
 log4j.category.org.springframework.data.mongodb=DEBUG

spring-data-mongodb-log4j/template.mf

@@ -0,0 +1,9 @@
+Bundle-SymbolicName: org.springframework.data.mongodb.log4j
+Bundle-Name: Spring Data Mongo DB Log4J Appender
+Bundle-Vendor: Pivotal Software, Inc.
+Bundle-ManifestVersion: 2
+Import-Package:
+ sun.reflect;version="0";resolution:=optional
+Import-Template:
+ com.mongodb.*;version="${mongo.osgi:[=.=.=,+1.0.0)}",
+ org.apache.log4j.*;version="${log4j:[=.=.=,+1.0.0)}"

spring-data-mongodb/pom.xml

@@ -11,14 +11,13 @@
 	<parent>
 		<groupId>org.springframework.data</groupId>
 		<artifactId>spring-data-mongodb-parent</artifactId>
-		<version>2.0.0.M1</version>
+		<version>1.10.1.RELEASE</version>
 		<relativePath>../pom.xml</relativePath>
 	</parent>
 
 	<properties>
 		<objenesis>1.3</objenesis>
 		<equalsverifier>1.5</equalsverifier>
-		<mongo>3.3.0</mongo>
 	</properties>
 
 	<dependencies>
@@ -79,52 +78,6 @@
 			<optional>true</optional>
 		</dependency>
 
-		<!-- reactive -->
-		<dependency>
-		 	<groupId>org.mongodb</groupId>
-			<artifactId>mongodb-driver-reactivestreams</artifactId>
-			<version>${mongo.reactivestreams}</version>
-			<optional>true</optional>
-		</dependency>
-
-		<dependency>
-		 	<groupId>org.mongodb</groupId>
-			<artifactId>mongodb-driver-async</artifactId>
-			<version>${mongo}</version>
-			<optional>true</optional>
-			<exclusions>
-				<exclusion>
-					<groupId>org.mongodb</groupId>
-					<artifactId>mongodb-driver-core</artifactId>
-				</exclusion>
-				<exclusion>
-					<groupId>org.mongodb</groupId>
-					<artifactId>bson</artifactId>
-				</exclusion>
-			</exclusions>
-		</dependency>
-
-		<dependency>
-		 	<groupId>io.projectreactor</groupId>
-			<artifactId>reactor-core</artifactId>
-			<version>${reactor}</version>
-			<optional>true</optional>
-		</dependency>
-
-		<dependency>
-		 	<groupId>io.reactivex</groupId>
-			<artifactId>rxjava</artifactId>
-			<version>${rxjava}</version>
-			<optional>true</optional>
-		</dependency>
-
-		<dependency>
-		 	<groupId>io.reactivex</groupId>
-			<artifactId>rxjava-reactive-streams</artifactId>
-			<version>${rxjava-reactive-streams}</version>
-			<optional>true</optional>
-		</dependency>
-
 		<!-- CDI -->
 		<dependency>
 			<groupId>javax.enterprise</groupId>
@@ -173,7 +126,7 @@
 		<dependency>
 			<groupId>org.hibernate</groupId>
 			<artifactId>hibernate-validator</artifactId>
-			<version>5.2.4.Final</version>
+			<version>4.2.0.Final</version>
 			<scope>test</scope>
 		</dependency>
 
@@ -259,11 +212,9 @@
 					</includes>
 					<excludes>
 						<exclude>**/PerformanceTests.java</exclude>
-						<exclude>**/ReactivePerformanceTests.java</exclude>
 					</excludes>
 					<systemPropertyVariables>
 						<java.util.logging.config.file>src/test/resources/logging.properties</java.util.logging.config.file>
-						<reactor.trace.cancel>true</reactor.trace.cancel>
 					</systemPropertyVariables>
 					<properties>
 						<property>

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/MongoDbFactory.java

@@ -20,7 +20,6 @@ import org.springframework.dao.support.PersistenceExceptionTranslator;
 import org.springframework.data.mongodb.core.MongoExceptionTranslator;
 
 import com.mongodb.DB;
-import com.mongodb.client.MongoDatabase;
 
 /**
  * Interface for factories creating {@link DB} instances.
@@ -36,7 +35,7 @@ public interface MongoDbFactory {
 	 * @return
 	 * @throws DataAccessException
 	 */
-	MongoDatabase getDb() throws DataAccessException;
+	DB getDb() throws DataAccessException;
 
 	/**
 	 * Creates a {@link DB} instance to access the database with the given name.
@@ -45,7 +44,7 @@ public interface MongoDbFactory {
 	 * @return
 	 * @throws DataAccessException
 	 */
-	MongoDatabase getDb(String dbName) throws DataAccessException;
+	DB getDb(String dbName) throws DataAccessException;
 
 	/**
 	 * Exposes a shared {@link MongoExceptionTranslator}.
@@ -53,6 +52,4 @@ public interface MongoDbFactory {
 	 * @return will never be {@literal null}.
 	 */
 	PersistenceExceptionTranslator getExceptionTranslator();
-
-	DB getLegacyDb();
 }

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/ReactiveMongoDatabaseFactory.java

@@ -1,56 +0,0 @@
-/*
- * Copyright 2016 the original author or authors.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package org.springframework.data.mongodb;
-
-import org.springframework.dao.DataAccessException;
-import org.springframework.dao.support.PersistenceExceptionTranslator;
-import org.springframework.data.mongodb.core.MongoExceptionTranslator;
-
-import com.mongodb.reactivestreams.client.MongoDatabase;
-
-/**
- * Interface for factories creating reactive {@link MongoDatabase} instances.
- *
- * @author Mark Paluch
- * @since 2.0
- */
-public interface ReactiveMongoDatabaseFactory {
-
-	/**
-	 * Creates a default {@link MongoDatabase} instance.
-	 *
-	 * @return
-	 * @throws DataAccessException
-	 */
-	MongoDatabase getMongoDatabase() throws DataAccessException;
-
-	/**
-	 * Creates a {@link MongoDatabase} instance to access the database with the given name.
-	 *
-	 * @param dbName must not be {@literal null} or empty.
-	 * @return
-	 * @throws DataAccessException
-	 */
-	MongoDatabase getMongoDatabase(String dbName) throws DataAccessException;
-
-	/**
-	 * Exposes a shared {@link MongoExceptionTranslator}.
-	 *
-	 * @return will never be {@literal null}.
-	 */
-	PersistenceExceptionTranslator getExceptionTranslator();
-}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/config/AbstractMongoConfiguration.java

@@ -15,16 +15,36 @@
  */
 package org.springframework.data.mongodb.config;
 
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.Set;
+
+import org.springframework.beans.factory.config.BeanDefinition;
 import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.core.convert.converter.Converter;
+import org.springframework.core.type.filter.AnnotationTypeFilter;
+import org.springframework.data.annotation.Persistent;
 import org.springframework.data.authentication.UserCredentials;
+import org.springframework.data.mapping.context.MappingContextIsNewStrategyFactory;
+import org.springframework.data.mapping.model.CamelCaseAbbreviatingFieldNamingStrategy;
+import org.springframework.data.mapping.model.FieldNamingStrategy;
+import org.springframework.data.mapping.model.PropertyNameFieldNamingStrategy;
 import org.springframework.data.mongodb.MongoDbFactory;
 import org.springframework.data.mongodb.core.MongoTemplate;
 import org.springframework.data.mongodb.core.SimpleMongoDbFactory;
+import org.springframework.data.mongodb.core.convert.CustomConversions;
 import org.springframework.data.mongodb.core.convert.DbRefResolver;
 import org.springframework.data.mongodb.core.convert.DefaultDbRefResolver;
 import org.springframework.data.mongodb.core.convert.MappingMongoConverter;
 import org.springframework.data.mongodb.core.mapping.Document;
+import org.springframework.data.mongodb.core.mapping.MongoMappingContext;
+import org.springframework.data.support.CachingIsNewStrategyFactory;
+import org.springframework.data.support.IsNewStrategyFactory;
+import org.springframework.util.ClassUtils;
+import org.springframework.util.StringUtils;
 
 import com.mongodb.Mongo;
 import com.mongodb.MongoClient;
@@ -37,11 +57,16 @@ import com.mongodb.MongoClient;
  * @author Thomas Darimont
  * @author Ryan Tenney
  * @author Christoph Strobl
- * @author Mark Paluch
- * @see MongoConfigurationSupport
  */
 @Configuration
-public abstract class AbstractMongoConfiguration extends MongoConfigurationSupport {
+public abstract class AbstractMongoConfiguration {
+
+	/**
+	 * Return the name of the database to connect to.
+	 * 
+	 * @return must not be {@literal null}.
+	 */
+	protected abstract String getDatabaseName();
 
 	/**
 	 * Return the name of the authentication database to use. Defaults to {@literal null} and will turn into the value
@@ -95,7 +120,7 @@ public abstract class AbstractMongoConfiguration extends MongoConfigurationSuppo
 	 * class' (the concrete class, not this one here) by default. So if you have a {@code com.acme.AppConfig} extending
 	 * {@link AbstractMongoConfiguration} the base package will be considered {@code com.acme} unless the method is
 	 * overridden to implement alternate behavior.
-	 *
+	 * 
 	 * @return the base package to scan for mapped {@link Document} classes or {@literal null} to not enable scanning for
 	 *         entities.
 	 * @deprecated use {@link #getMappingBasePackages()} instead.
@@ -107,6 +132,20 @@ public abstract class AbstractMongoConfiguration extends MongoConfigurationSuppo
 		return mappingBasePackage == null ? null : mappingBasePackage.getName();
 	}
 
+	/**
+	 * Returns the base packages to scan for MongoDB mapped entities at startup. Will return the package name of the
+	 * configuration class' (the concrete class, not this one here) by default. So if you have a
+	 * {@code com.acme.AppConfig} extending {@link AbstractMongoConfiguration} the base package will be considered
+	 * {@code com.acme} unless the method is overridden to implement alternate behavior.
+	 * 
+	 * @return the base packages to scan for mapped {@link Document} classes or an empty collection to not enable scanning
+	 *         for entities.
+	 * @since 1.10
+	 */
+	protected Collection<String> getMappingBasePackages() {
+		return Collections.singleton(getMappingBasePackage());
+	}
+
 	/**
 	 * Return {@link UserCredentials} to be used when connecting to the MongoDB instance or {@literal null} if none shall
 	 * be used.
@@ -120,6 +159,47 @@ public abstract class AbstractMongoConfiguration extends MongoConfigurationSuppo
 		return null;
 	}
 
+	/**
+	 * Creates a {@link MongoMappingContext} equipped with entity classes scanned from the mapping base package.
+	 * 
+	 * @see #getMappingBasePackage()
+	 * @return
+	 * @throws ClassNotFoundException
+	 */
+	@Bean
+	public MongoMappingContext mongoMappingContext() throws ClassNotFoundException {
+
+		MongoMappingContext mappingContext = new MongoMappingContext();
+		mappingContext.setInitialEntitySet(getInitialEntitySet());
+		mappingContext.setSimpleTypeHolder(customConversions().getSimpleTypeHolder());
+		mappingContext.setFieldNamingStrategy(fieldNamingStrategy());
+
+		return mappingContext;
+	}
+
+	/**
+	 * Returns a {@link MappingContextIsNewStrategyFactory} wrapped into a {@link CachingIsNewStrategyFactory}.
+	 * 
+	 * @return
+	 * @throws ClassNotFoundException
+	 */
+	@Bean
+	public IsNewStrategyFactory isNewStrategyFactory() throws ClassNotFoundException {
+		return new CachingIsNewStrategyFactory(new MappingContextIsNewStrategyFactory(mongoMappingContext()));
+	}
+
+	/**
+	 * Register custom {@link Converter}s in a {@link CustomConversions} object if required. These
+	 * {@link CustomConversions} will be registered with the {@link #mappingMongoConverter()} and
+	 * {@link #mongoMappingContext()}. Returns an empty {@link CustomConversions} instance by default.
+	 * 
+	 * @return must not be {@literal null}.
+	 */
+	@Bean
+	public CustomConversions customConversions() {
+		return new CustomConversions(Collections.emptyList());
+	}
+
 	/**
 	 * Creates a {@link MappingMongoConverter} using the configured {@link #mongoDbFactory()} and
 	 * {@link #mongoMappingContext()}. Will get {@link #customConversions()} applied.
@@ -139,4 +219,79 @@ public abstract class AbstractMongoConfiguration extends MongoConfigurationSuppo
 
 		return converter;
 	}
+
+	/**
+	 * Scans the mapping base package for classes annotated with {@link Document}. By default, it scans for entities in
+	 * all packages returned by {@link #getMappingBasePackages()}.
+	 * 
+	 * @see #getMappingBasePackages()
+	 * @return
+	 * @throws ClassNotFoundException
+	 */
+	protected Set<Class<?>> getInitialEntitySet() throws ClassNotFoundException {
+
+		Set<Class<?>> initialEntitySet = new HashSet<Class<?>>();
+
+		for (String basePackage : getMappingBasePackages()) {
+			initialEntitySet.addAll(scanForEntities(basePackage));
+		}
+
+		return initialEntitySet;
+	}
+
+	/**
+	 * Scans the given base package for entities, i.e. MongoDB specific types annotated with {@link Document} and
+	 * {@link Persistent}.
+	 * 
+	 * @param basePackage must not be {@literal null}.
+	 * @return
+	 * @throws ClassNotFoundException
+	 * @since 1.10
+	 */
+	protected Set<Class<?>> scanForEntities(String basePackage) throws ClassNotFoundException {
+
+		if (!StringUtils.hasText(basePackage)) {
+			return Collections.emptySet();
+		}
+
+		Set<Class<?>> initialEntitySet = new HashSet<Class<?>>();
+
+		if (StringUtils.hasText(basePackage)) {
+
+			ClassPathScanningCandidateComponentProvider componentProvider = new ClassPathScanningCandidateComponentProvider(
+					false);
+			componentProvider.addIncludeFilter(new AnnotationTypeFilter(Document.class));
+			componentProvider.addIncludeFilter(new AnnotationTypeFilter(Persistent.class));
+
+			for (BeanDefinition candidate : componentProvider.findCandidateComponents(basePackage)) {
+
+				initialEntitySet
+						.add(ClassUtils.forName(candidate.getBeanClassName(), AbstractMongoConfiguration.class.getClassLoader()));
+			}
+		}
+
+		return initialEntitySet;
+	}
+
+	/**
+	 * Configures whether to abbreviate field names for domain objects by configuring a
+	 * {@link CamelCaseAbbreviatingFieldNamingStrategy} on the {@link MongoMappingContext} instance created. For advanced
+	 * customization needs, consider overriding {@link #mappingMongoConverter()}.
+	 * 
+	 * @return
+	 */
+	protected boolean abbreviateFieldNames() {
+		return false;
+	}
+
+	/**
+	 * Configures a {@link FieldNamingStrategy} on the {@link MongoMappingContext} instance created.
+	 * 
+	 * @return
+	 * @since 1.5
+	 */
+	protected FieldNamingStrategy fieldNamingStrategy() {
+		return abbreviateFieldNames() ? new CamelCaseAbbreviatingFieldNamingStrategy()
+				: PropertyNameFieldNamingStrategy.INSTANCE;
+	}
 }

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/config/AbstractReactiveMongoConfiguration.java

@@ -1,92 +0,0 @@
-/*
- * Copyright 2016 the original author or authors.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package org.springframework.data.mongodb.config;
-
-import org.springframework.context.annotation.Bean;
-import org.springframework.context.annotation.Configuration;
-import org.springframework.data.mongodb.ReactiveMongoDatabaseFactory;
-import org.springframework.data.mongodb.core.MongoTemplate;
-import org.springframework.data.mongodb.core.ReactiveMongoOperations;
-import org.springframework.data.mongodb.core.SimpleReactiveMongoDatabaseFactory;
-import org.springframework.data.mongodb.core.ReactiveMongoTemplate;
-import org.springframework.data.mongodb.core.SimpleMongoDbFactory;
-import org.springframework.data.mongodb.core.convert.MappingMongoConverter;
-
-import com.mongodb.reactivestreams.client.MongoClient;
-
-/**
- * Base class for reactive Spring Data MongoDB configuration using JavaConfig.
- *
- * @author Mark Paluch
- * @since 2.0
- * @see MongoConfigurationSupport
- */
-@Configuration
-public abstract class AbstractReactiveMongoConfiguration extends MongoConfigurationSupport {
-
-	/**
-	 * Return the {@link MongoClient} instance to connect to. Annotate with {@link Bean} in case you want to expose a
-	 * {@link MongoClient} instance to the {@link org.springframework.context.ApplicationContext}.
-	 *
-	 * @return
-	 */
-	public abstract MongoClient mongoClient();
-
-	/**
-	 * Creates a {@link ReactiveMongoTemplate}.
-	 *
-	 * @return
-	 */
-	@Bean
-	public ReactiveMongoOperations reactiveMongoTemplate() throws Exception {
-		return new ReactiveMongoTemplate(mongoDbFactory(), mappingMongoConverter());
-	}
-
-	/**
-	 * Creates a {@link SimpleMongoDbFactory} to be used by the {@link MongoTemplate}. Will use the {@link Mongo} instance
-	 * configured in {@link #mongoClient()}.
-	 *
-	 * @see #mongoClient()
-	 * @see #reactiveMongoTemplate()
-	 * @return
-	 * @throws Exception
-	 */
-	@Bean
-	public ReactiveMongoDatabaseFactory mongoDbFactory() {
-		return new SimpleReactiveMongoDatabaseFactory(mongoClient(), getDatabaseName());
-	}
-
-	/**
-	 * Creates a {@link MappingMongoConverter} using the configured {@link #mongoDbFactory()} and
-	 * {@link #mongoMappingContext()}. Will get {@link #customConversions()} applied.
-	 *
-	 * @see #customConversions()
-	 * @see #mongoMappingContext()
-	 * @see #mongoDbFactory()
-	 * @return
-	 * @throws Exception
-	 */
-	@Bean
-	public MappingMongoConverter mappingMongoConverter() throws Exception {
-
-		MappingMongoConverter converter = new MappingMongoConverter(ReactiveMongoTemplate.NO_OP_REF_RESOLVER,
-				mongoMappingContext());
-		converter.setCustomConversions(customConversions());
-
-		return converter;
-	}
-}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/config/MappingMongoConverterParser.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2011-2016 the original author or authors.
+ * Copyright 2011-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -67,13 +67,12 @@ import org.w3c.dom.Element;
 
 /**
  * Bean definition parser for the {@code mapping-converter} element.
- *
+ * 
  * @author Jon Brisbin
  * @author Oliver Gierke
  * @author Maciej Walkowiak
  * @author Thomas Darimont
  * @author Christoph Strobl
- * @author Mark Paluch
  */
 public class MappingMongoConverterParser implements BeanDefinitionParser {
 
@@ -121,21 +120,16 @@ public class MappingMongoConverterParser implements BeanDefinitionParser {
 			converterBuilder.addPropertyValue("customConversions", conversionsDefinition);
 		}
 
-		if(!registry.containsBeanDefinition("indexOperationsProvider")){
-
-			BeanDefinitionBuilder indexOperationsProviderBuilder = BeanDefinitionBuilder.genericBeanDefinition("org.springframework.data.mongodb.core.DefaultIndexOperationsProvider");
-			indexOperationsProviderBuilder.addConstructorArgReference(dbFactoryRef);
-			parserContext.registerBeanComponent(new BeanComponentDefinition(indexOperationsProviderBuilder.getBeanDefinition(), "indexOperationsProvider"));
-		}
-
 		try {
 			registry.getBeanDefinition(INDEX_HELPER_BEAN_NAME);
 		} catch (NoSuchBeanDefinitionException ignored) {
-
+			if (!StringUtils.hasText(dbFactoryRef)) {
+				dbFactoryRef = DB_FACTORY_BEAN_NAME;
+			}
 			BeanDefinitionBuilder indexHelperBuilder = BeanDefinitionBuilder
 					.genericBeanDefinition(MongoPersistentEntityIndexCreator.class);
 			indexHelperBuilder.addConstructorArgReference(ctxRef);
-			indexHelperBuilder.addConstructorArgReference("indexOperationsProvider");
+			indexHelperBuilder.addConstructorArgReference(dbFactoryRef);
 			indexHelperBuilder.addDependsOn(ctxRef);
 
 			parserContext.registerBeanComponent(new BeanComponentDefinition(indexHelperBuilder.getBeanDefinition(),
@@ -354,7 +348,7 @@ public class MappingMongoConverterParser implements BeanDefinitionParser {
 
 	/**
 	 * {@link TypeFilter} that returns {@literal false} in case any of the given delegates matches.
-	 *
+	 * 
 	 * @author Oliver Gierke
 	 */
 	private static class NegatingFilter implements TypeFilter {
@@ -363,11 +357,13 @@ public class MappingMongoConverterParser implements BeanDefinitionParser {
 
 		/**
 		 * Creates a new {@link NegatingFilter} with the given delegates.
-		 *
+		 * 
 		 * @param filters
 		 */
 		public NegatingFilter(TypeFilter... filters) {
-			Assert.notNull(filters);
+
+			Assert.notNull(filters, "TypeFilters must not be null");
+
 			this.delegates = new HashSet<TypeFilter>(Arrays.asList(filters));
 		}
 

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/config/MongoConfigurationSupport.java

@@ -1,203 +0,0 @@
-/*
- * Copyright 2016 the original author or authors.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package org.springframework.data.mongodb.config;
-
-import java.util.Arrays;
-import java.util.Collection;
-import java.util.Collections;
-import java.util.HashSet;
-import java.util.Set;
-
-import org.springframework.beans.factory.config.BeanDefinition;
-import org.springframework.context.annotation.Bean;
-import org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider;
-import org.springframework.core.convert.converter.Converter;
-import org.springframework.core.type.filter.AnnotationTypeFilter;
-import org.springframework.data.annotation.Persistent;
-import org.springframework.data.authentication.UserCredentials;
-import org.springframework.data.mapping.context.MappingContext;
-import org.springframework.data.mapping.context.MappingContextIsNewStrategyFactory;
-import org.springframework.data.mapping.context.PersistentEntities;
-import org.springframework.data.mapping.model.CamelCaseAbbreviatingFieldNamingStrategy;
-import org.springframework.data.mapping.model.FieldNamingStrategy;
-import org.springframework.data.mapping.model.PropertyNameFieldNamingStrategy;
-import org.springframework.data.mongodb.MongoDbFactory;
-import org.springframework.data.mongodb.core.MongoTemplate;
-import org.springframework.data.mongodb.core.SimpleMongoDbFactory;
-import org.springframework.data.mongodb.core.convert.CustomConversions;
-import org.springframework.data.mongodb.core.convert.DbRefResolver;
-import org.springframework.data.mongodb.core.convert.DefaultDbRefResolver;
-import org.springframework.data.mongodb.core.convert.MappingMongoConverter;
-import org.springframework.data.mongodb.core.mapping.Document;
-import org.springframework.data.mongodb.core.mapping.MongoMappingContext;
-import org.springframework.data.support.CachingIsNewStrategyFactory;
-import org.springframework.data.support.IsNewStrategyFactory;
-import org.springframework.util.ClassUtils;
-import org.springframework.util.StringUtils;
-
-import com.mongodb.Mongo;
-import com.mongodb.MongoClient;
-
-/**
- * Base class for Spring Data MongoDB to be extended for JavaConfiguration usage.
- *
- * @author Mark Paluch
- * @since 2.0
- */
-public abstract class MongoConfigurationSupport {
-
-	/**
-	 * Return the name of the database to connect to.
-	 * 
-	 * @return must not be {@literal null}.
-	 */
-	protected abstract String getDatabaseName();
-
-	/**
-	 * Returns the base packages to scan for MongoDB mapped entities at startup. Will return the package name of the
-	 * configuration class' (the concrete class, not this one here) by default. So if you have a
-	 * {@code com.acme.AppConfig} extending {@link MongoConfigurationSupport} the base package will be considered
-	 * {@code com.acme} unless the method is overridden to implement alternate behavior.
-	 * 
-	 * @return the base packages to scan for mapped {@link Document} classes or an empty collection to not enable scanning
-	 *         for entities.
-	 * @since 1.10
-	 */
-	protected Collection<String> getMappingBasePackages() {
-
-		Package mappingBasePackage = getClass().getPackage();
-		return Collections.singleton(mappingBasePackage == null ? null : mappingBasePackage.getName());
-	}
-
-	/**
-	 * Creates a {@link MongoMappingContext} equipped with entity classes scanned from the mapping base package.
-	 * 
-	 * @see #getMappingBasePackage()
-	 * @return
-	 * @throws ClassNotFoundException
-	 */
-	@Bean
-	public MongoMappingContext mongoMappingContext() throws ClassNotFoundException {
-
-		MongoMappingContext mappingContext = new MongoMappingContext();
-		mappingContext.setInitialEntitySet(getInitialEntitySet());
-		mappingContext.setSimpleTypeHolder(customConversions().getSimpleTypeHolder());
-		mappingContext.setFieldNamingStrategy(fieldNamingStrategy());
-
-		return mappingContext;
-	}
-
-	/**
-	 * Returns a {@link MappingContextIsNewStrategyFactory} wrapped into a {@link CachingIsNewStrategyFactory}.
-	 *
-	 * @return
-	 * @throws ClassNotFoundException
-	 */
-	@Bean
-	public IsNewStrategyFactory isNewStrategyFactory() throws ClassNotFoundException {
-
-		return new CachingIsNewStrategyFactory(new MappingContextIsNewStrategyFactory(
-				new PersistentEntities(Arrays.<MappingContext<?, ?>> asList(new MappingContext[] { mongoMappingContext() }))));
-	}
-
-	/**
-	 * Register custom {@link Converter}s in a {@link CustomConversions} object if required. These
-	 * {@link CustomConversions} will be registered with the {@link #mappingMongoConverter()} and
-	 * {@link #mongoMappingContext()}. Returns an empty {@link CustomConversions} instance by default.
-	 *
-	 * @return must not be {@literal null}.
-	 */
-	@Bean
-	public CustomConversions customConversions() {
-		return new CustomConversions(Collections.emptyList());
-	}
-
-	/**
-	 * Scans the mapping base package for classes annotated with {@link Document}. By default, it scans for entities in
-	 * all packages returned by {@link #getMappingBasePackages()}.
-	 *
-	 * @see #getMappingBasePackages()
-	 * @return
-	 * @throws ClassNotFoundException
-	 */
-	protected Set<Class<?>> getInitialEntitySet() throws ClassNotFoundException {
-
-		Set<Class<?>> initialEntitySet = new HashSet<Class<?>>();
-
-		for (String basePackage : getMappingBasePackages()) {
-			initialEntitySet.addAll(scanForEntities(basePackage));
-		}
-
-		return initialEntitySet;
-	}
-
-	/**
-	 * Scans the given base package for entities, i.e. MongoDB specific types annotated with {@link Document} and
-	 * {@link Persistent}.
-	 *
-	 * @param basePackage must not be {@literal null}.
-	 * @return
-	 * @throws ClassNotFoundException
-	 * @since 1.10
-	 */
-	protected Set<Class<?>> scanForEntities(String basePackage) throws ClassNotFoundException {
-
-		if (!StringUtils.hasText(basePackage)) {
-			return Collections.emptySet();
-		}
-
-		Set<Class<?>> initialEntitySet = new HashSet<Class<?>>();
-
-		if (StringUtils.hasText(basePackage)) {
-
-			ClassPathScanningCandidateComponentProvider componentProvider = new ClassPathScanningCandidateComponentProvider(
-					false);
-			componentProvider.addIncludeFilter(new AnnotationTypeFilter(Document.class));
-			componentProvider.addIncludeFilter(new AnnotationTypeFilter(Persistent.class));
-
-			for (BeanDefinition candidate : componentProvider.findCandidateComponents(basePackage)) {
-
-				initialEntitySet
-						.add(ClassUtils.forName(candidate.getBeanClassName(), MongoConfigurationSupport.class.getClassLoader()));
-			}
-		}
-
-		return initialEntitySet;
-	}
-
-	/**
-	 * Configures whether to abbreviate field names for domain objects by configuring a
-	 * {@link CamelCaseAbbreviatingFieldNamingStrategy} on the {@link MongoMappingContext} instance created. For advanced
-	 * customization needs, consider overriding {@link #mappingMongoConverter()}.
-	 *
-	 * @return
-	 */
-	protected boolean abbreviateFieldNames() {
-		return false;
-	}
-
-	/**
-	 * Configures a {@link FieldNamingStrategy} on the {@link MongoMappingContext} instance created.
-	 *
-	 * @return
-	 * @since 1.5
-	 */
-	protected FieldNamingStrategy fieldNamingStrategy() {
-		return abbreviateFieldNames() ? new CamelCaseAbbreviatingFieldNamingStrategy()
-				: PropertyNameFieldNamingStrategy.INSTANCE;
-	}
-}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/config/MongoDbFactoryParser.java

@@ -32,7 +32,7 @@ import org.springframework.beans.factory.xml.BeanDefinitionParser;
 import org.springframework.beans.factory.xml.ParserContext;
 import org.springframework.data.authentication.UserCredentials;
 import org.springframework.data.config.BeanComponentDefinitionBuilder;
-import org.springframework.data.mongodb.core.MongoClientFactoryBean;
+import org.springframework.data.mongodb.core.MongoFactoryBean;
 import org.springframework.data.mongodb.core.SimpleMongoDbFactory;
 import org.springframework.util.StringUtils;
 import org.w3c.dom.Element;
@@ -131,7 +131,7 @@ public class MongoDbFactoryParser extends AbstractBeanDefinitionParser {
 	 */
 	private BeanDefinition registerMongoBeanDefinition(Element element, ParserContext parserContext) {
 
-		BeanDefinitionBuilder mongoBuilder = BeanDefinitionBuilder.genericBeanDefinition(MongoClientFactoryBean.class);
+		BeanDefinitionBuilder mongoBuilder = BeanDefinitionBuilder.genericBeanDefinition(MongoFactoryBean.class);
 		setPropertyValue(mongoBuilder, element, "host");
 		setPropertyValue(mongoBuilder, element, "port");
 

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/BulkOperations.java

@@ -21,7 +21,7 @@ import org.springframework.data.mongodb.core.query.Query;
 import org.springframework.data.mongodb.core.query.Update;
 import org.springframework.data.util.Pair;
 
-import com.mongodb.bulk.BulkWriteResult;
+import com.mongodb.BulkWriteResult;
 
 /**
  * Bulk operations for insert/update/remove actions on a collection. These bulks operation are available since MongoDB
@@ -38,7 +38,7 @@ public interface BulkOperations {
 	/**
 	 * Mode for bulk operation.
 	 **/
-	enum BulkMode {
+	public enum BulkMode {
 
 		/** Perform bulk operations in sequence. The first error will cancel processing. */
 		ORDERED,

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/CollectionCallback.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2016 the original author or authors.
+ * Copyright 2010-2011 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -15,30 +15,12 @@
  */
 package org.springframework.data.mongodb.core;
 
-import org.bson.Document;
+import com.mongodb.DBCollection;
+import com.mongodb.MongoException;
 import org.springframework.dao.DataAccessException;
 
-import com.mongodb.MongoException;
-import com.mongodb.client.MongoCollection;
-
-/**
- * Callback interface for executing actions against a {@link MongoCollection}
- *
- * @author Mark Pollak
- * @author Grame Rocher
- * @author Oliver Gierke
- * @author John Brisbin
- * @auhtor Christoph Strobl
- * @since 1.0
- */
 public interface CollectionCallback<T> {
 
-	/**
-	 * @param collection never {@literal null}.
-	 * @return
-	 * @throws MongoException
-	 * @throws DataAccessException
-	 */
-	T doInCollection(MongoCollection<Document> collection) throws MongoException, DataAccessException;
+	T doInCollection(DBCollection collection) throws MongoException, DataAccessException;
 
 }

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/CursorPreparer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2010 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -15,15 +15,12 @@
  */
 package org.springframework.data.mongodb.core;
 
-import org.bson.Document;
-
-import com.mongodb.client.FindIterable;
+import com.mongodb.DBCursor;
 
 /**
- * Simple callback interface to allow customization of a {@link FindIterable}.
+ * Simple callback interface to allow customization of a {@link DBCursor}.
  * 
  * @author Oliver Gierke
- * @author Christoph Strobl
  */
 interface CursorPreparer {
 
@@ -32,5 +29,5 @@ interface CursorPreparer {
 	 * 
 	 * @param cursor
 	 */
-	FindIterable<Document> prepare(FindIterable<Document> cursor);
+	DBCursor prepare(DBCursor cursor);
 }

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/DbCallback.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2016 the original author or authors.
+ * Copyright 2010-2011 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -15,16 +15,11 @@
  */
 package org.springframework.data.mongodb.core;
 
+import com.mongodb.DB;
+import com.mongodb.MongoException;
 import org.springframework.dao.DataAccessException;
 
-import com.mongodb.MongoException;
-import com.mongodb.client.MongoDatabase;
-
-/**
- *
- * @param <T>
- */
 public interface DbCallback<T> {
 
-	T doInDB(MongoDatabase db) throws MongoException, DataAccessException;
+	T doInDB(DB db) throws MongoException, DataAccessException;
 }

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/DefaultBulkOperations.java

@@ -15,11 +15,9 @@
  */
 package org.springframework.data.mongodb.core;
 
-import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
 
-import org.bson.Document;
 import org.springframework.dao.DataAccessException;
 import org.springframework.dao.support.PersistenceExceptionTranslator;
 import org.springframework.data.mongodb.core.query.Query;
@@ -27,16 +25,14 @@ import org.springframework.data.mongodb.core.query.Update;
 import org.springframework.data.util.Pair;
 import org.springframework.util.Assert;
 
+import com.mongodb.BasicDBObject;
 import com.mongodb.BulkWriteException;
+import com.mongodb.BulkWriteOperation;
+import com.mongodb.BulkWriteRequestBuilder;
+import com.mongodb.BulkWriteResult;
+import com.mongodb.DBCollection;
+import com.mongodb.DBObject;
 import com.mongodb.WriteConcern;
-import com.mongodb.client.MongoCollection;
-import com.mongodb.client.model.BulkWriteOptions;
-import com.mongodb.client.model.DeleteManyModel;
-import com.mongodb.client.model.InsertOneModel;
-import com.mongodb.client.model.UpdateManyModel;
-import com.mongodb.client.model.UpdateOneModel;
-import com.mongodb.client.model.UpdateOptions;
-import com.mongodb.client.model.WriteModel;
 
 /**
  * Default implementation for {@link BulkOperations}.
@@ -51,14 +47,13 @@ class DefaultBulkOperations implements BulkOperations {
 	private final MongoOperations mongoOperations;
 	private final BulkMode bulkMode;
 	private final String collectionName;
+	private final Class<?> entityType;
 
 	private PersistenceExceptionTranslator exceptionTranslator;
 	private WriteConcernResolver writeConcernResolver;
 	private WriteConcern defaultWriteConcern;
 
-	private BulkWriteOptions bulkOptions;
-
-	List<WriteModel<Document>> models = new ArrayList<WriteModel<Document>>();
+	private BulkWriteOperation bulk;
 
 	/**
 	 * Creates a new {@link DefaultBulkOperations} for the given {@link MongoOperations}, {@link BulkMode}, collection
@@ -79,11 +74,12 @@ class DefaultBulkOperations implements BulkOperations {
 		this.mongoOperations = mongoOperations;
 		this.bulkMode = bulkMode;
 		this.collectionName = collectionName;
+		this.entityType = entityType;
 
 		this.exceptionTranslator = new MongoExceptionTranslator();
 		this.writeConcernResolver = DefaultWriteConcernResolver.INSTANCE;
 
-		this.bulkOptions = initBulkOperation();
+		this.bulk = initBulkOperation();
 	}
 
 	/**
@@ -123,7 +119,15 @@ class DefaultBulkOperations implements BulkOperations {
 
 		Assert.notNull(document, "Document must not be null!");
 
-		models.add(new InsertOneModel<Document>((Document) mongoOperations.getConverter().convertToMongoType(document)));
+		if (document instanceof DBObject) {
+
+			bulk.insert((DBObject) document);
+			return this;
+		}
+
+		DBObject sink = new BasicDBObject();
+		mongoOperations.getConverter().write(document, sink);
+		bulk.insert(sink);
 		return this;
 	}
 
@@ -235,7 +239,8 @@ class DefaultBulkOperations implements BulkOperations {
 
 		Assert.notNull(query, "Query must not be null!");
 
-		models.add(new DeleteManyModel<Document>(query.getQueryObject()));
+		bulk.find(query.getQueryObject()).remove();
+
 		return this;
 	}
 
@@ -260,16 +265,15 @@ class DefaultBulkOperations implements BulkOperations {
 	 * @see org.springframework.data.mongodb.core.BulkOperations#executeBulk()
 	 */
 	@Override
-	public com.mongodb.bulk.BulkWriteResult execute() {
+	public BulkWriteResult execute() {
+
+		MongoAction action = new MongoAction(defaultWriteConcern, MongoActionOperation.BULK, collectionName, entityType,
+				null, null);
+		WriteConcern writeConcern = writeConcernResolver.resolve(action);
 
 		try {
 
-			MongoCollection<Document> collection = mongoOperations.getCollection(collectionName);
-			if (defaultWriteConcern != null) {
-				collection = collection.withWriteConcern(defaultWriteConcern);
-			}
-
-			return collection.bulkWrite(models, bulkOptions);
+			return writeConcern == null ? bulk.execute() : bulk.execute(writeConcern);
 
 		} catch (BulkWriteException o_O) {
 
@@ -277,7 +281,7 @@ class DefaultBulkOperations implements BulkOperations {
 			throw toThrow == null ? o_O : toThrow;
 
 		} finally {
-			this.bulkOptions = initBulkOperation();
+			this.bulk = initBulkOperation();
 		}
 	}
 
@@ -295,26 +299,39 @@ class DefaultBulkOperations implements BulkOperations {
 		Assert.notNull(query, "Query must not be null!");
 		Assert.notNull(update, "Update must not be null!");
 
-		UpdateOptions options = new UpdateOptions();
-		options.upsert(upsert);
+		BulkWriteRequestBuilder builder = bulk.find(query.getQueryObject());
+
+		if (upsert) {
+
+			if (multi) {
+				builder.upsert().update(update.getUpdateObject());
+			} else {
+				builder.upsert().updateOne(update.getUpdateObject());
+			}
 
-		if (multi) {
-			models.add(new UpdateManyModel<Document>(query.getQueryObject(), update.getUpdateObject(), options));
 		} else {
-			models.add(new UpdateOneModel<Document>(query.getQueryObject(), update.getUpdateObject(), options));
+
+			if (multi) {
+				builder.update(update.getUpdateObject());
+			} else {
+				builder.updateOne(update.getUpdateObject());
+			}
 		}
+
 		return this;
 	}
 
-	private final BulkWriteOptions initBulkOperation() {
+	private final BulkWriteOperation initBulkOperation() {
+
+		DBCollection collection = mongoOperations.getCollection(collectionName);
 
-		BulkWriteOptions options = new BulkWriteOptions();
 		switch (bulkMode) {
 			case ORDERED:
-				return options.ordered(true);
+				return collection.initializeOrderedBulkOperation();
 			case UNORDERED:
-				return options.ordered(false);
+				return collection.initializeUnorderedBulkOperation();
 		}
+
 		throw new IllegalStateException("BulkMode was null!");
 	}
 }

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/DefaultIndexOperations.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2011-2016 the original author or authors.
+ * Copyright 2011-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -15,22 +15,20 @@
  */
 package org.springframework.data.mongodb.core;
 
-import static org.springframework.data.mongodb.core.MongoTemplate.*;
-
 import java.util.ArrayList;
+import java.util.Collection;
 import java.util.List;
 
-import org.bson.Document;
 import org.springframework.dao.DataAccessException;
-import org.springframework.data.mongodb.MongoDbFactory;
+import org.springframework.data.mongodb.core.convert.QueryMapper;
 import org.springframework.data.mongodb.core.index.IndexDefinition;
 import org.springframework.data.mongodb.core.index.IndexInfo;
+import org.springframework.data.mongodb.core.mapping.MongoPersistentEntity;
 import org.springframework.util.Assert;
 
+import com.mongodb.DBCollection;
+import com.mongodb.DBObject;
 import com.mongodb.MongoException;
-import com.mongodb.client.MongoCollection;
-import com.mongodb.client.MongoCursor;
-import com.mongodb.client.model.IndexOptions;
 
 /**
  * Default implementation of {@link IndexOperations}.
@@ -39,44 +37,89 @@ import com.mongodb.client.model.IndexOptions;
  * @author Oliver Gierke
  * @author Komi Innocent
  * @author Christoph Strobl
- * @author Mark Paluch
  */
 public class DefaultIndexOperations implements IndexOperations {
 
-	private final MongoDbFactory mongoDbFactory;
+	private static final String PARTIAL_FILTER_EXPRESSION_KEY = "partialFilterExpression";
+
+	private final MongoOperations mongoOperations;
 	private final String collectionName;
+	private final QueryMapper mapper;
+	private final Class<?> type;
 
 	/**
 	 * Creates a new {@link DefaultIndexOperations}.
 	 * 
-	 * @param mongoDbFactory must not be {@literal null}.
+	 * @param mongoOperations must not be {@literal null}.
 	 * @param collectionName must not be {@literal null}.
 	 */
-	public DefaultIndexOperations(MongoDbFactory mongoDbFactory, String collectionName) {
+	public DefaultIndexOperations(MongoOperations mongoOperations, String collectionName) {
+		this(mongoOperations, collectionName, null);
+	}
 
-		Assert.notNull(mongoDbFactory, "MongoDbFactory must not be null!");
+	/**
+	 * Creates a new {@link DefaultIndexOperations}.
+	 *
+	 * @param mongoOperations must not be {@literal null}.
+	 * @param collectionName must not be {@literal null}.
+	 * @param type Type used for mapping potential partial index filter expression. Can be {@literal null}.
+	 * @since 1.10
+	 */
+	public DefaultIndexOperations(MongoOperations mongoOperations, String collectionName, Class<?> type) {
+
+		Assert.notNull(mongoOperations, "MongoOperations must not be null!");
 		Assert.notNull(collectionName, "Collection name can not be null!");
 
-		this.mongoDbFactory = mongoDbFactory;
+		this.mongoOperations = mongoOperations;
 		this.collectionName = collectionName;
+		this.mapper = new QueryMapper(mongoOperations.getConverter());
+		this.type = type;
 	}
 
 	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.data.mongodb.core.IndexOperations#ensureIndex(org.springframework.data.mongodb.core.index.IndexDefinition)
 	 */
-	public String ensureIndex(final IndexDefinition indexDefinition) {
+	public void ensureIndex(final IndexDefinition indexDefinition) {
 
-		return execute(collection -> {
+		mongoOperations.execute(collectionName, new CollectionCallback<Object>() {
+			public Object doInCollection(DBCollection collection) throws MongoException, DataAccessException {
+				DBObject indexOptions = indexDefinition.getIndexOptions();
 
-			Document indexOptions = indexDefinition.getIndexOptions();
+				if (indexOptions != null && indexOptions.containsField(PARTIAL_FILTER_EXPRESSION_KEY)) {
 
-			if (indexOptions != null) {
+					Assert.isInstanceOf(DBObject.class, indexOptions.get(PARTIAL_FILTER_EXPRESSION_KEY));
 
-				IndexOptions ops = IndexConverters.indexDefinitionToIndexOptionsConverter().convert(indexDefinition);
-				return collection.createIndex(indexDefinition.getIndexKeys(), ops);
+					indexOptions.put(PARTIAL_FILTER_EXPRESSION_KEY,
+							mapper.getMappedObject((DBObject) indexOptions.get(PARTIAL_FILTER_EXPRESSION_KEY),
+									lookupPersistentEntity(type, collectionName)));
+				}
+
+				if (indexOptions != null) {
+					collection.createIndex(indexDefinition.getIndexKeys(), indexOptions);
+				} else {
+					collection.createIndex(indexDefinition.getIndexKeys());
+				}
+				return null;
+			}
+
+			private MongoPersistentEntity<?> lookupPersistentEntity(Class<?> entityType, String collection) {
+
+				if (entityType != null) {
+					return mongoOperations.getConverter().getMappingContext().getPersistentEntity(entityType);
+				}
+
+				Collection<? extends MongoPersistentEntity<?>> entities = mongoOperations.getConverter().getMappingContext()
+						.getPersistentEntities();
+
+				for (MongoPersistentEntity<?> entity : entities) {
+					if (entity.getCollection().equals(collection)) {
+						return entity;
+					}
+				}
+
+				return null;
 			}
-			return collection.createIndex(indexDefinition.getIndexKeys());
 		});
 	}
 
@@ -85,10 +128,11 @@ public class DefaultIndexOperations implements IndexOperations {
 	 * @see org.springframework.data.mongodb.core.IndexOperations#dropIndex(java.lang.String)
 	 */
 	public void dropIndex(final String name) {
-
-		execute(collection -> {
-			collection.dropIndex(name);
-			return null;
+		mongoOperations.execute(collectionName, new CollectionCallback<Void>() {
+			public Void doInCollection(DBCollection collection) throws MongoException, DataAccessException {
+				collection.dropIndex(name);
+				return null;
+			}
 		});
 
 	}
@@ -101,46 +145,45 @@ public class DefaultIndexOperations implements IndexOperations {
 		dropIndex("*");
 	}
 
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.IndexOperations#resetIndexCache()
+	 */
+	@Deprecated
+	public void resetIndexCache() {
+		mongoOperations.execute(collectionName, new CollectionCallback<Void>() {
+			public Void doInCollection(DBCollection collection) throws MongoException, DataAccessException {
+
+				ReflectiveDBCollectionInvoker.resetIndexCache(collection);
+				return null;
+			}
+		});
+	}
+
 	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.data.mongodb.core.IndexOperations#getIndexInfo()
 	 */
 	public List<IndexInfo> getIndexInfo() {
 
-		return execute(new CollectionCallback<List<IndexInfo>>() {
+		return mongoOperations.execute(collectionName, new CollectionCallback<List<IndexInfo>>() {
 
-			public List<IndexInfo> doInCollection(MongoCollection<Document> collection)
-					throws MongoException, DataAccessException {
+			public List<IndexInfo> doInCollection(DBCollection collection) throws MongoException, DataAccessException {
 
-				MongoCursor<Document> cursor = collection.listIndexes(Document.class).iterator();
-				return getIndexData(cursor);
+				List<DBObject> dbObjectList = collection.getIndexInfo();
+				return getIndexData(dbObjectList);
 			}
 
-			private List<IndexInfo> getIndexData(MongoCursor<Document> cursor) {
+			private List<IndexInfo> getIndexData(List<DBObject> dbObjectList) {
 
 				List<IndexInfo> indexInfoList = new ArrayList<IndexInfo>();
 
-				while (cursor.hasNext()) {
-
-					Document ix = cursor.next();
-					IndexInfo indexInfo = IndexConverters.documentToIndexInfoConverter().convert(ix);
-					indexInfoList.add(indexInfo);
+				for (DBObject ix : dbObjectList) {
+					indexInfoList.add(IndexInfo.indexInfoOf(ix));
 				}
 
 				return indexInfoList;
 			}
 		});
 	}
-
-	public <T> T execute(CollectionCallback<T> callback) {
-
-		Assert.notNull(callback);
-
-		try {
-			MongoCollection<Document> collection = mongoDbFactory.getDb().getCollection(collectionName);
-			return callback.doInCollection(collection);
-		} catch (RuntimeException e) {
-			throw potentiallyConvertRuntimeException(e, mongoDbFactory.getExceptionTranslator());
-		}
-	}
 }

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/DefaultIndexOperationsProvider.java

@@ -1,45 +0,0 @@
-/*
- * Copyright 2016 the original author or authors.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-package org.springframework.data.mongodb.core;
-
-import org.springframework.data.mongodb.MongoDbFactory;
-
-/**
- * {@link IndexOperationsProvider} to obtain {@link IndexOperations} from a given {@link MongoDbFactory}. TODO: Review
- * me
- *
- * @author Mark Paluch
- * @since 2.0
- */
-class DefaultIndexOperationsProvider implements IndexOperationsProvider {
-
-	private final MongoDbFactory mongoDbFactory;
-
-	/**
-	 * @param mongoDbFactory must not be {@literal null}.
-	 */
-	DefaultIndexOperationsProvider(MongoDbFactory mongoDbFactory) {
-		this.mongoDbFactory = mongoDbFactory;
-	}
-
-	/* (non-Javadoc)
-	 * @see org.springframework.data.mongodb.core.IndexOperationsProvider#reactiveIndexOps(java.lang.String)
-	 */
-	@Override
-	public IndexOperations indexOps(String collectionName) {
-		return new DefaultIndexOperations(mongoDbFactory, collectionName);
-	}
-}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/DefaultReactiveIndexOperations.java

@@ -1,102 +0,0 @@
-/*
- * Copyright 2016 the original author or authors.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-package org.springframework.data.mongodb.core;
-
-import org.bson.Document;
-import org.springframework.data.mongodb.core.index.IndexDefinition;
-import org.springframework.data.mongodb.core.index.IndexInfo;
-import org.springframework.util.Assert;
-
-import com.mongodb.reactivestreams.client.ListIndexesPublisher;
-
-import reactor.core.publisher.Flux;
-import reactor.core.publisher.Mono;
-
-/**
- * Default implementation of {@link IndexOperations}.
- *
- * @author Mark Paluch
- * @since 1.11
- */
-public class DefaultReactiveIndexOperations implements ReactiveIndexOperations {
-
-	private final ReactiveMongoOperations mongoOperations;
-	private final String collectionName;
-
-	/**
-	 * Creates a new {@link DefaultReactiveIndexOperations}.
-	 *
-	 * @param mongoOperations must not be {@literal null}.
-	 * @param collectionName must not be {@literal null}.
-	 */
-	public DefaultReactiveIndexOperations(ReactiveMongoOperations mongoOperations, String collectionName) {
-
-		Assert.notNull(mongoOperations, "ReactiveMongoOperations must not be null!");
-		Assert.notNull(collectionName, "Collection must not be null!");
-
-		this.mongoOperations = mongoOperations;
-		this.collectionName = collectionName;
-	}
-
-	/* (non-Javadoc)
-	 * @see org.springframework.data.mongodb.core.ReactiveIndexOperations#ensureIndex(org.springframework.data.mongodb.core.index.IndexDefinition)
-	 */
-	public Mono<String> ensureIndex(final IndexDefinition indexDefinition) {
-
-		return mongoOperations.execute(collectionName, (ReactiveCollectionCallback<String>) collection -> {
-
-			Document indexOptions = indexDefinition.getIndexOptions();
-
-			if (indexOptions != null) {
-				return collection.createIndex(indexDefinition.getIndexKeys(),
-						IndexConverters.indexDefinitionToIndexOptionsConverter().convert(indexDefinition));
-			}
-
-			return collection.createIndex(indexDefinition.getIndexKeys());
-		}).next();
-	}
-
-	/* (non-Javadoc)
-	 * @see org.springframework.data.mongodb.core.ReactiveIndexOperations#dropIndex(java.lang.String)
-	 */
-	public Mono<Void> dropIndex(final String name) {
-
-		return mongoOperations.execute(collectionName, collection -> {
-
-			return Mono.from(collection.dropIndex(name));
-		}).flatMap(success -> Mono.<Void>empty()).next();
-	}
-
-	/* (non-Javadoc)
-	 * @see org.springframework.data.mongodb.core.ReactiveIndexOperations#dropAllIndexes()
-	 */
-	public Mono<Void> dropAllIndexes() {
-		return dropIndex("*");
-	}
-
-	/* (non-Javadoc)
-	 * @see org.springframework.data.mongodb.core.ReactiveIndexOperations#getIndexInfo()
-	 */
-	public Flux<IndexInfo> getIndexInfo() {
-
-		return mongoOperations.execute(collectionName, collection -> {
-
-			ListIndexesPublisher<Document> indexesPublisher = collection.listIndexes(Document.class);
-
-			return Flux.from(indexesPublisher).map(IndexConverters.documentToIndexInfoConverter()::convert);
-		});
-	}
-}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/DefaultScriptOperations.java

@@ -20,13 +20,11 @@ import static org.springframework.data.mongodb.core.query.Criteria.*;
 import static org.springframework.data.mongodb.core.query.Query.*;
 
 import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.Collections;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
 
-import org.bson.Document;
 import org.bson.types.ObjectId;
 import org.springframework.dao.DataAccessException;
 import org.springframework.data.mongodb.core.script.ExecutableMongoScript;
@@ -36,9 +34,8 @@ import org.springframework.util.CollectionUtils;
 import org.springframework.util.ObjectUtils;
 import org.springframework.util.StringUtils;
 
-import com.mongodb.BasicDBList;
+import com.mongodb.DB;
 import com.mongodb.MongoException;
-import com.mongodb.client.MongoDatabase;
 
 /**
  * Default implementation of {@link ScriptOperations} capable of saving and executing {@link ServerSideJavaScript}.
@@ -100,13 +97,8 @@ class DefaultScriptOperations implements ScriptOperations {
 		return mongoOperations.execute(new DbCallback<Object>() {
 
 			@Override
-			public Object doInDB(MongoDatabase db) throws MongoException, DataAccessException {
-
-				Document command = new Document("$eval", script.getCode());
-				BasicDBList commandArgs = new BasicDBList();
-				commandArgs.addAll(Arrays.asList(convertScriptArgs(false, args)));
-				command.append("args", commandArgs);
-				return db.runCommand(command).get("retval");
+			public Object doInDB(DB db) throws MongoException, DataAccessException {
+				return db.eval(script.getCode(), convertScriptArgs(false, args));
 			}
 		});
 	}
@@ -123,10 +115,8 @@ class DefaultScriptOperations implements ScriptOperations {
 		return mongoOperations.execute(new DbCallback<Object>() {
 
 			@Override
-			public Object doInDB(MongoDatabase db) throws MongoException, DataAccessException {
-
-				return db.runCommand(new Document("eval", String.format("%s(%s)", scriptName, convertAndJoinScriptArgs(args))))
-						.get("retval");
+			public Object doInDB(DB db) throws MongoException, DataAccessException {
+				return db.eval(String.format("%s(%s)", scriptName, convertAndJoinScriptArgs(args)));
 			}
 		});
 	}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/DocumentCallbackHandler.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2016 the original author or authors.
+ * Copyright 2010-2011 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -15,26 +15,24 @@
  */
 package org.springframework.data.mongodb.core;
 
-import org.bson.Document;
 import org.springframework.dao.DataAccessException;
 
+import com.mongodb.DBObject;
 import com.mongodb.MongoException;
 
 /**
  * An interface used by {@link MongoTemplate} for processing documents returned from a MongoDB query on a per-document
  * basis. Implementations of this interface perform the actual work of prcoessing each document but don't need to worry
- * about exception handling. {@MongoException}s will be caught and translated by the calling MongoTemplate An
- * DocumentCallbackHandler is typically stateful: It keeps the result state within the object, to be available later for
- * later inspection.
+ * about exception handling. {@MongoException}s will be caught and translated by the calling
+ * MongoTemplate
+ * 
+ * An DocumentCallbackHandler is typically stateful: It keeps the result state within the object, to be available later
+ * for later inspection.
  * 
  * @author Mark Pollack
- * @author Grame Rocher
- * @author Oliver Gierke
- * @author John Brisbin
- * @author Christoph Strobl
- * @since 1.0
+ * 
  */
 public interface DocumentCallbackHandler {
 
-	void processDocument(Document document) throws MongoException, DataAccessException;
+	void processDocument(DBObject dbObject) throws MongoException, DataAccessException;
 }

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/FindPublisherPreparer.java

@@ -1,34 +0,0 @@
-/*
- * Copyright 2016 the original author or authors.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-package org.springframework.data.mongodb.core;
-
-import com.mongodb.DBCursor;
-import com.mongodb.reactivestreams.client.FindPublisher;
-
-/**
- * Simple callback interface to allow customization of a {@link FindPublisher}.
- *
- * @author Mark Paluch
- */
-interface FindPublisherPreparer {
-
-	/**
-	 * Prepare the given cursor (apply limits, skips and so on). Returns the prepared cursor.
-	 *
-	 * @param cursor
-	 */
-	<T> FindPublisher<T> prepare(FindPublisher<T> findPublisher);
-}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/GeoCommandStatistics.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016 the original author or authors.
+ * Copyright 2016-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -15,29 +15,29 @@
  */
 package org.springframework.data.mongodb.core;
 
-import org.bson.Document;
 import org.springframework.util.Assert;
 
+import com.mongodb.BasicDBObject;
+import com.mongodb.DBObject;
+
 /**
  * Value object to mitigate different representations of geo command execution results in MongoDB.
  * 
  * @author Oliver Gierke
- * @author Christoph Strobl
  * @soundtrack Fruitcake - Jeff Coffin (The Inside of the Outside)
- * @since 1.9
  */
 class GeoCommandStatistics {
 
-	private static final GeoCommandStatistics NONE = new GeoCommandStatistics(new Document());
+	private static final GeoCommandStatistics NONE = new GeoCommandStatistics(new BasicDBObject());
 
-	private final Document source;
+	private final DBObject source;
 
 	/**
 	 * Creates a new {@link GeoCommandStatistics} instance with the given source document.
 	 * 
 	 * @param source must not be {@literal null}.
 	 */
-	private GeoCommandStatistics(Document source) {
+	private GeoCommandStatistics(DBObject source) {
 
 		Assert.notNull(source, "Source document must not be null!");
 		this.source = source;
@@ -49,12 +49,12 @@ class GeoCommandStatistics {
 	 * @param commandResult must not be {@literal null}.
 	 * @return
 	 */
-	public static GeoCommandStatistics from(Document commandResult) {
+	public static GeoCommandStatistics from(DBObject commandResult) {
 
 		Assert.notNull(commandResult, "Command result must not be null!");
 
 		Object stats = commandResult.get("stats");
-		return stats == null ? NONE : new GeoCommandStatistics((Document) stats);
+		return stats == null ? NONE : new GeoCommandStatistics((DBObject) stats);
 	}
 
 	/**
@@ -62,7 +62,7 @@ class GeoCommandStatistics {
 	 * didn't return any result introduced in MongoDB 3.2 RC1.
 	 * 
 	 * @return
-	 * @see https://jira.mongodb.org/browse/SERVER-21024
+	 * @see <a href="https://jira.mongodb.org/browse/SERVER-21024">MongoDB Jira SERVER-21024</a>
 	 */
 	public double getAverageDistance() {
 

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/GeoJsonConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2015 the original author or authors.
+ * Copyright 2015-2016 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,15 +17,14 @@ package org.springframework.data.mongodb.core;
 
 import org.springframework.context.annotation.Bean;
 import org.springframework.data.mongodb.core.geo.GeoJsonModule;
-import org.springframework.data.web.config.SpringDataWebConfigurationMixin;
+import org.springframework.data.web.config.SpringDataJacksonModules;
 
 /**
  * Configuration class to expose {@link GeoJsonModule} as a Spring bean.
  * 
  * @author Oliver Gierke
  */
-@SpringDataWebConfigurationMixin
-public class GeoJsonConfiguration {
+public class GeoJsonConfiguration implements SpringDataJacksonModules {
 
 	@Bean
 	public GeoJsonModule geoJsonModule() {

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/IndexConverters.java

@@ -1,166 +0,0 @@
-/*
- * Copyright 2016 the original author or authors.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package org.springframework.data.mongodb.core;
-
-import static org.springframework.data.domain.Sort.Direction.*;
-
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.Collection;
-import java.util.List;
-import java.util.concurrent.TimeUnit;
-
-import org.bson.Document;
-import org.springframework.core.convert.converter.Converter;
-import org.springframework.data.mongodb.core.index.IndexDefinition;
-import org.springframework.data.mongodb.core.index.IndexField;
-import org.springframework.data.mongodb.core.index.IndexInfo;
-import org.springframework.util.ObjectUtils;
-
-import com.mongodb.client.model.IndexOptions;
-
-/**
- * {@link Converter Converters} for index-related MongoDB documents/types.
- *
- * @author Mark Paluch
- * @author Christoph Strobl
- * @since 2.0
- */
-abstract class IndexConverters {
-
-	private static final Converter<IndexDefinition, IndexOptions> DEFINITION_TO_MONGO_INDEX_OPTIONS;
-	private static final Converter<Document, IndexInfo> DOCUMENT_INDEX_INFO;
-
-	private static final Double ONE = Double.valueOf(1);
-	private static final Double MINUS_ONE = Double.valueOf(-1);
-	private static final Collection<String> TWO_D_IDENTIFIERS = Arrays.asList("2d", "2dsphere");
-
-	static {
-
-		DEFINITION_TO_MONGO_INDEX_OPTIONS = getIndexDefinitionIndexOptionsConverter();
-		DOCUMENT_INDEX_INFO = getDocumentIndexInfoConverter();
-	}
-
-	private IndexConverters() {
-
-	}
-
-	static Converter<IndexDefinition, IndexOptions> indexDefinitionToIndexOptionsConverter() {
-		return DEFINITION_TO_MONGO_INDEX_OPTIONS;
-	}
-
-	static Converter<Document, IndexInfo> documentToIndexInfoConverter() {
-		return DOCUMENT_INDEX_INFO;
-	}
-
-	private static Converter<IndexDefinition, IndexOptions> getIndexDefinitionIndexOptionsConverter() {
-
-		return indexDefinition -> {
-
-			Document indexOptions = indexDefinition.getIndexOptions();
-			IndexOptions ops = new IndexOptions();
-
-			if (indexOptions.containsKey("name")) {
-				ops = ops.name(indexOptions.get("name").toString());
-			}
-			if (indexOptions.containsKey("unique")) {
-				ops = ops.unique((Boolean) indexOptions.get("unique"));
-			}
-			if (indexOptions.containsKey("sparse")) {
-				ops = ops.sparse((Boolean) indexOptions.get("sparse"));
-			}
-			if (indexOptions.containsKey("background")) {
-				ops = ops.background((Boolean) indexOptions.get("background"));
-			}
-			if (indexOptions.containsKey("expireAfterSeconds")) {
-				ops = ops.expireAfter((Long) indexOptions.get("expireAfterSeconds"), TimeUnit.SECONDS);
-			}
-			if (indexOptions.containsKey("min")) {
-				ops = ops.min(((Number) indexOptions.get("min")).doubleValue());
-			}
-			if (indexOptions.containsKey("max")) {
-				ops = ops.max(((Number) indexOptions.get("max")).doubleValue());
-			}
-			if (indexOptions.containsKey("bits")) {
-				ops = ops.bits((Integer) indexOptions.get("bits"));
-			}
-			if (indexOptions.containsKey("bucketSize")) {
-				ops = ops.bucketSize(((Number) indexOptions.get("bucketSize")).doubleValue());
-			}
-			if (indexOptions.containsKey("default_language")) {
-				ops = ops.defaultLanguage(indexOptions.get("default_language").toString());
-			}
-			if (indexOptions.containsKey("language_override")) {
-				ops = ops.languageOverride(indexOptions.get("language_override").toString());
-			}
-			if (indexOptions.containsKey("weights")) {
-				ops = ops.weights((org.bson.Document) indexOptions.get("weights"));
-			}
-
-			for (String key : indexOptions.keySet()) {
-				if (ObjectUtils.nullSafeEquals("2dsphere", indexOptions.get(key))) {
-					ops = ops.sphereVersion(2);
-				}
-			}
-
-			return ops;
-		};
-	}
-
-	private static Converter<Document, IndexInfo> getDocumentIndexInfoConverter() {
-
-		return ix -> {
-			Document keyDocument = (Document) ix.get("key");
-			int numberOfElements = keyDocument.keySet().size();
-
-			List<IndexField> indexFields = new ArrayList<IndexField>(numberOfElements);
-
-			for (String key : keyDocument.keySet()) {
-
-				Object value = keyDocument.get(key);
-
-				if (TWO_D_IDENTIFIERS.contains(value)) {
-					indexFields.add(IndexField.geo(key));
-				} else if ("text".equals(value)) {
-
-					Document weights = (Document) ix.get("weights");
-					for (String fieldName : weights.keySet()) {
-						indexFields.add(IndexField.text(fieldName, Float.valueOf(weights.get(fieldName).toString())));
-					}
-
-				} else {
-
-					Double keyValue = new Double(value.toString());
-
-					if (ONE.equals(keyValue)) {
-						indexFields.add(IndexField.create(key, ASC));
-					} else if (MINUS_ONE.equals(keyValue)) {
-						indexFields.add(IndexField.create(key, DESC));
-					}
-				}
-			}
-
-			String name = ix.get("name").toString();
-
-			boolean unique = ix.containsKey("unique") ? (Boolean) ix.get("unique") : false;
-			boolean sparse = ix.containsKey("sparse") ? (Boolean) ix.get("sparse") : false;
-
-			String language = ix.containsKey("default_language") ? (String) ix.get("default_language") : "";
-			return new IndexInfo(indexFields, name, unique, sparse, language);
-		};
-	}
-}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/IndexOperations.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2011-2016 the original author or authors.
+ * Copyright 2011-2015 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -35,7 +35,7 @@ public interface IndexOperations {
 	 * 
 	 * @param indexDefinition must not be {@literal null}.
 	 */
-	String ensureIndex(IndexDefinition indexDefinition);
+	void ensureIndex(IndexDefinition indexDefinition);
 
 	/**
 	 * Drops an index from this collection.
@@ -49,6 +49,15 @@ public interface IndexOperations {
 	 */
 	void dropAllIndexes();
 
+	/**
+	 * Clears all indices that have not yet been applied to this collection.
+	 * 
+	 * @deprecated since 1.7. The MongoDB Java driver version 3.0 does no longer support reseting the index cache.
+	 * @throws {@link UnsupportedOperationException} when used with MongoDB Java driver version 3.0.
+	 */
+	@Deprecated
+	void resetIndexCache();
+
 	/**
 	 * Returns the index information on the collection.
 	 * 

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/IndexOperationsAdapter.java

@@ -1,66 +0,0 @@
-/*
- * Copyright 2016. the original author or authors.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package org.springframework.data.mongodb.core;
-
-import java.util.List;
-
-import org.springframework.data.mongodb.core.index.IndexDefinition;
-import org.springframework.data.mongodb.core.index.IndexInfo;
-import org.springframework.util.Assert;
-
-/**
- * Adapter for creating synchronous {@link IndexOperations}.
- *
- * @author Christoph Strobl
- * @since 2.0
- */
-public interface IndexOperationsAdapter extends IndexOperations {
-
-	/**
-	 * Obtain a blocking variant of {@link IndexOperations} wrapping {@link ReactiveIndexOperations}.
-	 *
-	 * @param reactiveIndexOperations must not be {@literal null}.
-	 * @return never {@literal null}
-	 */
-	static IndexOperationsAdapter blocking(ReactiveIndexOperations reactiveIndexOperations) {
-
-		Assert.notNull(reactiveIndexOperations, "ReactiveIndexOperations must not be null!");
-
-		return new IndexOperationsAdapter() {
-
-			@Override
-			public String ensureIndex(IndexDefinition indexDefinition) {
-				return reactiveIndexOperations.ensureIndex(indexDefinition).block();
-			}
-
-			@Override
-			public void dropIndex(String name) {
-				reactiveIndexOperations.dropIndex(name).block();
-			}
-
-			@Override
-			public void dropAllIndexes() {
-				reactiveIndexOperations.dropAllIndexes().block();
-			}
-
-			@Override
-			public List<IndexInfo> getIndexInfo() {
-				return reactiveIndexOperations.getIndexInfo().collectList().block();
-			}
-		};
-	}
-}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/MongoAction.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2011-2016 the original author or authors.
+ * Copyright 2011-2012 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -15,9 +15,9 @@
  */
 package org.springframework.data.mongodb.core;
 
-import org.bson.Document;
 import org.springframework.util.Assert;
 
+import com.mongodb.DBObject;
 import com.mongodb.WriteConcern;
 
 /**
@@ -31,7 +31,6 @@ import com.mongodb.WriteConcern;
  * 
  * @author Mark Pollack
  * @author Oliver Gierke
- * @author Christoph Strobl
  */
 public class MongoAction {
 
@@ -39,8 +38,8 @@ public class MongoAction {
 	private final WriteConcern defaultWriteConcern;
 	private final Class<?> entityType;
 	private final MongoActionOperation mongoActionOperation;
-	private final Document query;
-	private final Document document;
+	private final DBObject query;
+	private final DBObject document;
 
 	/**
 	 * Create an instance of a {@link MongoAction}.
@@ -49,11 +48,11 @@ public class MongoAction {
 	 * @param mongoActionOperation action being taken against the collection
 	 * @param collectionName the collection name, must not be {@literal null} or empty.
 	 * @param entityType the POJO that is being operated against
-	 * @param document the converted Document from the POJO or Spring Update object
-	 * @param query the converted Document from the Spring Query object
+	 * @param document the converted DBObject from the POJO or Spring Update object
+	 * @param query the converted DBObject from the Spring Query object
 	 */
-	public MongoAction(WriteConcern defaultWriteConcern, MongoActionOperation mongoActionOperation, String collectionName,
-			Class<?> entityType, Document document, Document query) {
+	public MongoAction(WriteConcern defaultWriteConcern, MongoActionOperation mongoActionOperation,
+			String collectionName, Class<?> entityType, DBObject document, DBObject query) {
 
 		Assert.hasText(collectionName, "Collection name must not be null or empty!");
 
@@ -73,6 +72,14 @@ public class MongoAction {
 		return defaultWriteConcern;
 	}
 
+	/**
+	 * @deprecated use {@link #getEntityType()} instead.
+	 */
+	@Deprecated
+	public Class<?> getEntityClass() {
+		return entityType;
+	}
+
 	public Class<?> getEntityType() {
 		return entityType;
 	}
@@ -81,11 +88,11 @@ public class MongoAction {
 		return mongoActionOperation;
 	}
 
-	public Document getQuery() {
+	public DBObject getQuery() {
 		return query;
 	}
 
-	public Document getDocument() {
+	public DBObject getDocument() {
 		return document;
 	}
 

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/MongoAdmin.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2011-2013 the original author or authors.
+ * Copyright 2011-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -27,7 +27,8 @@ import com.mongodb.Mongo;
  * Mongo server administration exposed via JMX annotations
  * 
  * @author Mark Pollack
- * @author Thomas Darimont
+ * @author Thomas Darimont
+ * @author Mark Paluch
  */
 @ManagedResource(description = "Mongo Admin Operations")
 public class MongoAdmin implements MongoAdminOperations {
@@ -35,10 +36,11 @@ public class MongoAdmin implements MongoAdminOperations {
 	private final Mongo mongo;
 	private String username;
 	private String password;
-	private String authenticationDatabaseName;
+	private String authenticationDatabaseName;
 
 	public MongoAdmin(Mongo mongo) {
-		Assert.notNull(mongo);
+
+		Assert.notNull(mongo, "Mongo must not be null!");
 		this.mongo = mongo;
 	}
 
@@ -84,16 +86,16 @@ public class MongoAdmin implements MongoAdminOperations {
 		this.password = password;
 	}
 
-	/**
-	 * Sets the authenticationDatabaseName to use to authenticate with the Mongo database.
-	 * 
-	 * @param authenticationDatabaseName The authenticationDatabaseName to use.
-	 */
-	public void setAuthenticationDatabaseName(String authenticationDatabaseName) {
-		this.authenticationDatabaseName = authenticationDatabaseName;
-	}
-
+	/**
+	 * Sets the authenticationDatabaseName to use to authenticate with the Mongo database.
+	 * 
+	 * @param authenticationDatabaseName The authenticationDatabaseName to use.
+	 */
+	public void setAuthenticationDatabaseName(String authenticationDatabaseName) {
+		this.authenticationDatabaseName = authenticationDatabaseName;
+	}
+
 	DB getDB(String databaseName) {
-		return MongoDbUtils.getDB(mongo, databaseName, new UserCredentials(username, password), authenticationDatabaseName);
+		return MongoDbUtils.getDB(mongo, databaseName, new UserCredentials(username, password), authenticationDatabaseName);
 	}
 }

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/MongoExceptionTranslator.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2016 the original author or authors.
+ * Copyright 2010-2015 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,7 +19,6 @@ import java.util.Arrays;
 import java.util.HashSet;
 import java.util.Set;
 
-import org.bson.BsonInvalidOperationException;
 import org.springframework.dao.DataAccessException;
 import org.springframework.dao.DataAccessResourceFailureException;
 import org.springframework.dao.DataIntegrityViolationException;
@@ -34,10 +33,7 @@ import org.springframework.data.mongodb.util.MongoDbErrorCodes;
 import org.springframework.util.ClassUtils;
 
 import com.mongodb.BulkWriteException;
-import com.mongodb.MongoBulkWriteException;
 import com.mongodb.MongoException;
-import com.mongodb.MongoServerException;
-import com.mongodb.bulk.BulkWriteError;
 
 /**
  * Simple {@link PersistenceExceptionTranslator} for Mongo. Convert the given runtime exception to an appropriate
@@ -61,7 +57,7 @@ public class MongoExceptionTranslator implements PersistenceExceptionTranslator
 			Arrays.asList("MongoInternalException"));
 
 	private static final Set<String> DATA_INTEGRETY_EXCEPTIONS = new HashSet<String>(
-			Arrays.asList("WriteConcernException", "MongoWriteException", "MongoBulkWriteException"));
+			Arrays.asList("WriteConcernException"));
 
 	/*
 	 * (non-Javadoc)
@@ -71,10 +67,6 @@ public class MongoExceptionTranslator implements PersistenceExceptionTranslator
 
 		// Check for well-known MongoException subclasses.
 
-		if (ex instanceof BsonInvalidOperationException) {
-			throw new InvalidDataAccessApiUsageException(ex.getMessage(), ex);
-		}
-
 		String exception = ClassUtils.getShortName(ClassUtils.getUserClass(ex.getClass()));
 
 		if (DULICATE_KEY_EXCEPTIONS.contains(exception)) {
@@ -90,20 +82,6 @@ public class MongoExceptionTranslator implements PersistenceExceptionTranslator
 		}
 
 		if (DATA_INTEGRETY_EXCEPTIONS.contains(exception)) {
-
-			if (ex instanceof MongoServerException) {
-				if (((MongoServerException) ex).getCode() == 11000) {
-					return new DuplicateKeyException(ex.getMessage(), ex);
-				}
-				if (ex instanceof MongoBulkWriteException) {
-					for (BulkWriteError x : ((MongoBulkWriteException) ex).getWriteErrors()) {
-						if (x.getCode() == 11000) {
-							return new DuplicateKeyException(ex.getMessage(), ex);
-						}
-					}
-				}
-			}
-
 			return new DataIntegrityViolationException(ex.getMessage(), ex);
 		}
 

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/MongoOperations.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2011-2016 the original author or authors.
+ * Copyright 2011-2015 the original author or authors.
  * 
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,7 +19,6 @@ import java.util.Collection;
 import java.util.List;
 import java.util.Set;
 
-import org.bson.Document;
 import org.springframework.data.geo.GeoResults;
 import org.springframework.data.mongodb.core.BulkOperations.BulkMode;
 import org.springframework.data.mongodb.core.aggregation.Aggregation;
@@ -37,12 +36,13 @@ import org.springframework.data.mongodb.core.query.Query;
 import org.springframework.data.mongodb.core.query.Update;
 import org.springframework.data.util.CloseableIterator;
 
+import com.mongodb.CommandResult;
 import com.mongodb.Cursor;
 import com.mongodb.DB;
+import com.mongodb.DBCollection;
+import com.mongodb.DBObject;
 import com.mongodb.ReadPreference;
-import com.mongodb.client.MongoCollection;
-import com.mongodb.client.result.DeleteResult;
-import com.mongodb.client.result.UpdateResult;
+import com.mongodb.WriteResult;
 
 /**
  * Interface that specifies a basic set of MongoDB operations. Implemented by {@link MongoTemplate}. Not often used but
@@ -69,12 +69,12 @@ public interface MongoOperations {
 
 	/**
 	 * Execute the a MongoDB command expressed as a JSON string. This will call the method JSON.parse that is part of the
-	 * MongoDB driver to convert the JSON string to a Document. Any errors that result from executing this command will be
+	 * MongoDB driver to convert the JSON string to a DBObject. Any errors that result from executing this command will be
 	 * converted into Spring's DAO exception hierarchy.
 	 * 
 	 * @param jsonCommand a MongoDB command expressed as a JSON string.
 	 */
-	Document executeCommand(String jsonCommand);
+	CommandResult executeCommand(String jsonCommand);
 
 	/**
 	 * Execute a MongoDB command. Any errors that result from executing this command will be converted into Spring's DAO
@@ -82,7 +82,19 @@ public interface MongoOperations {
 	 * 
 	 * @param command a MongoDB command
 	 */
-	Document executeCommand(Document command);
+	CommandResult executeCommand(DBObject command);
+
+	/**
+	 * Execute a MongoDB command. Any errors that result from executing this command will be converted into Spring's DAO
+	 * exception hierarchy.
+	 * 
+	 * @param command a MongoDB command
+	 * @param options query options to use
+	 * @deprecated since 1.7. Please use {@link #executeCommand(DBObject, ReadPreference)}, as the MongoDB Java driver
+	 *             version 3 no longer supports this operation.
+	 */
+	@Deprecated
+	CommandResult executeCommand(DBObject command, int options);
 
 	/**
 	 * Execute a MongoDB command. Any errors that result from executing this command will be converted into Spring's data
@@ -93,7 +105,7 @@ public interface MongoOperations {
 	 * @return
 	 * @since 1.7
 	 */
-	Document executeCommand(Document command, ReadPreference readPreference);
+	CommandResult executeCommand(DBObject command, ReadPreference readPreference);
 
 	/**
 	 * Execute a MongoDB query and iterate over the query results on a per-document basis with a DocumentCallbackHandler.
@@ -140,6 +152,22 @@ public interface MongoOperations {
 	 */
 	<T> T execute(String collectionName, CollectionCallback<T> action);
 
+	/**
+	 * Executes the given {@link DbCallback} within the same connection to the database so as to ensure consistency in a
+	 * write heavy environment where you may read the data that you wrote. See the comments on {@see <a
+	 * href=http://www.mongodb.org/display/DOCS/Java+Driver+Concurrency>Java Driver Concurrency</a>}
+	 * <p/>
+	 * Allows for returning a result object, that is a domain object or a collection of domain objects.
+	 * 
+	 * @param <T> return type
+	 * @param action callback that specified the MongoDB actions to perform on the DB instance
+	 * @return a result object returned by the action or <tt>null</tt>
+	 * @deprecated since 1.7 as the MongoDB Java driver version 3 does not longer support request boundaries via
+	 *             {@link DB#requestStart()} and {@link DB#requestDone()}.
+	 */
+	@Deprecated
+	<T> T executeInSession(DbCallback<T> action);
+
 	/**
 	 * Executes the given {@link Query} on the entity collection of the specified {@code entityType} backed by a Mongo DB
 	 * {@link Cursor}.
@@ -175,7 +203,7 @@ public interface MongoOperations {
 	 * @param entityClass class that determines the collection to create
 	 * @return the created collection
 	 */
-	<T> MongoCollection<Document> createCollection(Class<T> entityClass);
+	<T> DBCollection createCollection(Class<T> entityClass);
 
 	/**
 	 * Create a collection with a name based on the provided entity class using the options.
@@ -184,7 +212,7 @@ public interface MongoOperations {
 	 * @param collectionOptions options to use when creating the collection.
 	 * @return the created collection
 	 */
-	<T> MongoCollection<Document> createCollection(Class<T> entityClass, CollectionOptions collectionOptions);
+	<T> DBCollection createCollection(Class<T> entityClass, CollectionOptions collectionOptions);
 
 	/**
 	 * Create an uncapped collection with the provided name.
@@ -192,7 +220,7 @@ public interface MongoOperations {
 	 * @param collectionName name of the collection
 	 * @return the created collection
 	 */
-	MongoCollection<Document> createCollection(String collectionName);
+	DBCollection createCollection(String collectionName);
 
 	/**
 	 * Create a collection with the provided name and options.
@@ -201,7 +229,7 @@ public interface MongoOperations {
 	 * @param collectionOptions options to use when creating the collection.
 	 * @return the created collection
 	 */
-	MongoCollection<Document> createCollection(String collectionName, CollectionOptions collectionOptions);
+	DBCollection createCollection(String collectionName, CollectionOptions collectionOptions);
 
 	/**
 	 * A set of collection names.
@@ -218,7 +246,7 @@ public interface MongoOperations {
 	 * @param collectionName name of the collection
 	 * @return an existing collection or a newly created one.
 	 */
-	MongoCollection<Document> getCollection(String collectionName);
+	DBCollection getCollection(String collectionName);
 
 	/**
 	 * Check to see if a collection with a name indicated by the entity class exists.
@@ -836,7 +864,7 @@ public interface MongoOperations {
 	 * @param entityClass class that determines the collection to use
 	 * @return the WriteResult which lets you access the results of the previous write.
 	 */
-	UpdateResult upsert(Query query, Update update, Class<?> entityClass);
+	WriteResult upsert(Query query, Update update, Class<?> entityClass);
 
 	/**
 	 * Performs an upsert. If no document is found that matches the query, a new document is created and inserted by
@@ -848,7 +876,7 @@ public interface MongoOperations {
 	 * @param collectionName name of the collection to update the object in
 	 * @return the WriteResult which lets you access the results of the previous write.
 	 */
-	UpdateResult upsert(Query query, Update update, String collectionName);
+	WriteResult upsert(Query query, Update update, String collectionName);
 
 	/**
 	 * Performs an upsert. If no document is found that matches the query, a new document is created and inserted by
@@ -860,7 +888,7 @@ public interface MongoOperations {
 	 * @param collectionName name of the collection to update the object in
 	 * @return the WriteResult which lets you access the results of the previous write.
 	 */
-	UpdateResult upsert(Query query, Update update, Class<?> entityClass, String collectionName);
+	WriteResult upsert(Query query, Update update, Class<?> entityClass, String collectionName);
 
 	/**
 	 * Updates the first object that is found in the collection of the entity class that matches the query document with
@@ -872,7 +900,7 @@ public interface MongoOperations {
 	 * @param entityClass class that determines the collection to use
 	 * @return the WriteResult which lets you access the results of the previous write.
 	 */
-	UpdateResult updateFirst(Query query, Update update, Class<?> entityClass);
+	WriteResult updateFirst(Query query, Update update, Class<?> entityClass);
 
 	/**
 	 * Updates the first object that is found in the specified collection that matches the query document criteria with
@@ -884,7 +912,7 @@ public interface MongoOperations {
 	 * @param collectionName name of the collection to update the object in
 	 * @return the WriteResult which lets you access the results of the previous write.
 	 */
-	UpdateResult updateFirst(Query query, Update update, String collectionName);
+	WriteResult updateFirst(Query query, Update update, String collectionName);
 
 	/**
 	 * Updates the first object that is found in the specified collection that matches the query document criteria with
@@ -897,7 +925,7 @@ public interface MongoOperations {
 	 * @param collectionName name of the collection to update the object in
 	 * @return the WriteResult which lets you access the results of the previous write.
 	 */
-	UpdateResult updateFirst(Query query, Update update, Class<?> entityClass, String collectionName);
+	WriteResult updateFirst(Query query, Update update, Class<?> entityClass, String collectionName);
 
 	/**
 	 * Updates all objects that are found in the collection for the entity class that matches the query document criteria
@@ -909,7 +937,7 @@ public interface MongoOperations {
 	 * @param entityClass class that determines the collection to use
 	 * @return the WriteResult which lets you access the results of the previous write.
 	 */
-	UpdateResult updateMulti(Query query, Update update, Class<?> entityClass);
+	WriteResult updateMulti(Query query, Update update, Class<?> entityClass);
 
 	/**
 	 * Updates all objects that are found in the specified collection that matches the query document criteria with the
@@ -921,7 +949,7 @@ public interface MongoOperations {
 	 * @param collectionName name of the collection to update the object in
 	 * @return the WriteResult which lets you access the results of the previous write.
 	 */
-	UpdateResult updateMulti(Query query, Update update, String collectionName);
+	WriteResult updateMulti(Query query, Update update, String collectionName);
 
 	/**
 	 * Updates all objects that are found in the collection for the entity class that matches the query document criteria
@@ -934,14 +962,14 @@ public interface MongoOperations {
 	 * @param collectionName name of the collection to update the object in
 	 * @return the WriteResult which lets you access the results of the previous write.
 	 */
-	UpdateResult updateMulti(final Query query, final Update update, Class<?> entityClass, String collectionName);
+	WriteResult updateMulti(final Query query, final Update update, Class<?> entityClass, String collectionName);
 
 	/**
 	 * Remove the given object from the collection by id.
 	 * 
 	 * @param object
 	 */
-	DeleteResult remove(Object object);
+	WriteResult remove(Object object);
 
 	/**
 	 * Removes the given object from the given collection.
@@ -949,7 +977,7 @@ public interface MongoOperations {
 	 * @param object
 	 * @param collection must not be {@literal null} or empty.
 	 */
-	DeleteResult remove(Object object, String collection);
+	WriteResult remove(Object object, String collection);
 
 	/**
 	 * Remove all documents that match the provided query document criteria from the the collection used to store the
@@ -958,7 +986,7 @@ public interface MongoOperations {
 	 * @param query
 	 * @param entityClass
 	 */
-	DeleteResult remove(Query query, Class<?> entityClass);
+	WriteResult remove(Query query, Class<?> entityClass);
 
 	/**
 	 * Remove all documents that match the provided query document criteria from the the collection used to store the
@@ -968,7 +996,7 @@ public interface MongoOperations {
 	 * @param entityClass
 	 * @param collectionName
 	 */
-	DeleteResult remove(Query query, Class<?> entityClass, String collectionName);
+	WriteResult remove(Query query, Class<?> entityClass, String collectionName);
 
 	/**
 	 * Remove all documents from the specified collection that match the provided query document criteria. There is no
@@ -977,7 +1005,7 @@ public interface MongoOperations {
 	 * @param query the query document that specifies the criteria used to remove a record
 	 * @param collectionName name of the collection where the objects will removed
 	 */
-	DeleteResult remove(Query query, String collectionName);
+	WriteResult remove(Query query, String collectionName);
 
 	/**
 	 * Returns and removes all documents form the specified collection that match the provided query.

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/ReactiveCollectionCallback.java

@@ -1,34 +0,0 @@
-/*
- * Copyright 2016 the original author or authors.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-package org.springframework.data.mongodb.core;
-
-import org.springframework.dao.DataAccessException;
-
-import com.mongodb.MongoException;
-import com.mongodb.reactivestreams.client.MongoCollection;
-import org.bson.Document;
-import org.reactivestreams.Publisher;
-
-/**
- * @author Mark Paluch
- * @param <T>
- * @since 2.0
- */
-public interface ReactiveCollectionCallback<T> {
-
-	Publisher<T> doInCollection(MongoCollection<Document> collection) throws MongoException, DataAccessException;
-
-}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/ReactiveDatabaseCallback.java

@@ -1,32 +0,0 @@
-/*
- * Copyright 2016 the original author or authors.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-package org.springframework.data.mongodb.core;
-
-import org.springframework.dao.DataAccessException;
-
-import com.mongodb.MongoException;
-import com.mongodb.reactivestreams.client.MongoDatabase;
-import org.reactivestreams.Publisher;
-
-/**
- * @author Mark Paluch
- * @param <T>
- * @since 2.0
- */
-public interface ReactiveDatabaseCallback<T> {
-
-	Publisher<T> doInDB(MongoDatabase db) throws MongoException, DataAccessException;
-}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/ReactiveIndexOperations.java

@@ -1,62 +0,0 @@
-/*
- * Copyright 2016 the original author or authors.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-package org.springframework.data.mongodb.core;
-
-import java.util.List;
-
-import org.springframework.data.mongodb.core.index.IndexDefinition;
-import org.springframework.data.mongodb.core.index.IndexInfo;
-
-import reactor.core.publisher.Flux;
-import reactor.core.publisher.Mono;
-
-/**
- * Index operations on a collection.
- *
- * @author Mark Paluch
- * @author Christoph Strobl
- * @since 2.0
- */
-public interface ReactiveIndexOperations {
-
-	/**
-	 * Ensure that an index for the provided {@link IndexDefinition} exists for the collection indicated by the entity
-	 * class. If not it will be created.
-	 *
-	 * @param indexDefinition must not be {@literal null}.
-	 */
-	Mono<String> ensureIndex(IndexDefinition indexDefinition);
-
-	/**
-	 * Drops an index from this collection.
-	 *
-	 * @param name name of index to drop
-	 */
-	Mono<Void> dropIndex(String name);
-
-	/**
-	 * Drops all indices from this collection.
-	 */
-	Mono<Void> dropAllIndexes();
-
-	/**
-	 * Returns the index information on the collection.
-	 *
-	 * @return index information on the collection
-	 */
-	Flux<IndexInfo> getIndexInfo();
-
-}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/ReactiveMongoClientFactoryBean.java

@@ -1,129 +0,0 @@
-/*
- * Copyright 2016 the original author or authors.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package org.springframework.data.mongodb.core;
-
-import org.springframework.beans.factory.config.AbstractFactoryBean;
-import org.springframework.dao.DataAccessException;
-import org.springframework.dao.support.PersistenceExceptionTranslator;
-import org.springframework.util.StringUtils;
-
-import com.mongodb.async.client.MongoClientSettings;
-import com.mongodb.reactivestreams.client.MongoClient;
-import com.mongodb.reactivestreams.client.MongoClients;
-
-/**
- * Convenient factory for configuring a reactive streams {@link MongoClient}.
- *
- * @author Mark Paluch
- * @author Christoph Strobl
- * @since 2.0
- */
-public class ReactiveMongoClientFactoryBean extends AbstractFactoryBean<MongoClient>
-		implements PersistenceExceptionTranslator {
-
-	private static final PersistenceExceptionTranslator DEFAULT_EXCEPTION_TRANSLATOR = new MongoExceptionTranslator();
-
-	private String connectionString;
-	private String host;
-	private Integer port;
-	private MongoClientSettings mongoClientSettings;
-	private PersistenceExceptionTranslator exceptionTranslator = DEFAULT_EXCEPTION_TRANSLATOR;
-
-	/**
-	 * Configures the host to connect to.
-	 *
-	 * @param host
-	 */
-	public void setHost(String host) {
-		this.host = host;
-	}
-
-	/**
-	 * Configures the port to connect to.
-	 *
-	 * @param port
-	 */
-	public void setPort(int port) {
-		this.port = port;
-	}
-
-	/**
-	 * Configures the connection string.
-	 *
-	 * @param connectionString
-	 */
-	public void setConnectionString(String connectionString) {
-		this.connectionString = connectionString;
-	}
-
-	/**
-	 * Configures the mongo client settings.
-	 *
-	 * @param mongoClientSettings
-	 */
-	public void setMongoClientSettings(MongoClientSettings mongoClientSettings) {
-		this.mongoClientSettings = mongoClientSettings;
-	}
-
-	/**
-	 * Configures the {@link PersistenceExceptionTranslator} to use.
-	 *
-	 * @param exceptionTranslator
-	 */
-	public void setExceptionTranslator(PersistenceExceptionTranslator exceptionTranslator) {
-		this.exceptionTranslator = exceptionTranslator == null ? DEFAULT_EXCEPTION_TRANSLATOR : exceptionTranslator;
-	}
-
-	@Override
-	public Class<?> getObjectType() {
-		return MongoClient.class;
-	}
-
-	@Override
-	protected MongoClient createInstance() throws Exception {
-
-		if (mongoClientSettings != null) {
-			return MongoClients.create(mongoClientSettings);
-		}
-
-		if (StringUtils.hasText(connectionString)) {
-			return MongoClients.create(connectionString);
-		}
-
-		if (StringUtils.hasText(host)) {
-
-			if (port != null) {
-				return MongoClients.create(String.format("mongodb://%s:%d", host, port));
-			}
-
-			return MongoClients.create(String.format("mongodb://%s", host));
-		}
-
-		throw new IllegalStateException(
-				"Cannot create MongoClients. One of the following is required: mongoClientSettings, connectionString or host/port");
-	}
-
-	@Override
-	protected void destroyInstance(MongoClient instance) throws Exception {
-		instance.close();
-	}
-
-	@Override
-	public DataAccessException translateExceptionIfPossible(RuntimeException ex) {
-		return exceptionTranslator.translateExceptionIfPossible(ex);
-	}
-}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/ReactiveMongoClientSettingsFactoryBean.java

@@ -1,206 +0,0 @@
-/*
- * Copyright 2016 the original author or authors.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-package org.springframework.data.mongodb.core;
-
-import java.util.ArrayList;
-import java.util.List;
-
-import org.bson.codecs.configuration.CodecRegistry;
-import org.springframework.beans.factory.config.AbstractFactoryBean;
-import org.springframework.util.Assert;
-
-import com.mongodb.MongoCredential;
-import com.mongodb.ReadConcern;
-import com.mongodb.ReadPreference;
-import com.mongodb.WriteConcern;
-import com.mongodb.async.client.MongoClientSettings;
-import com.mongodb.connection.ClusterSettings;
-import com.mongodb.connection.ConnectionPoolSettings;
-import com.mongodb.connection.ServerSettings;
-import com.mongodb.connection.SocketSettings;
-import com.mongodb.connection.SslSettings;
-import com.mongodb.connection.StreamFactoryFactory;
-
-/**
- * A factory bean for construction of a {@link MongoClientSettings} instance to be used with the async MongoDB driver.
- *
- * @author Mark Paluch
- * @since 2.0
- */
-public class ReactiveMongoClientSettingsFactoryBean extends AbstractFactoryBean<MongoClientSettings> {
-
-	private static final MongoClientSettings DEFAULT_MONGO_SETTINGS = MongoClientSettings.builder().build();
-
-	private ReadPreference readPreference = DEFAULT_MONGO_SETTINGS.getReadPreference();
-	private WriteConcern writeConcern = DEFAULT_MONGO_SETTINGS.getWriteConcern();
-	private ReadConcern readConcern = DEFAULT_MONGO_SETTINGS.getReadConcern();
-	private List<MongoCredential> credentialList = new ArrayList<>();
-	private StreamFactoryFactory streamFactoryFactory = DEFAULT_MONGO_SETTINGS.getStreamFactoryFactory();
-	private CodecRegistry codecRegistry = DEFAULT_MONGO_SETTINGS.getCodecRegistry();
-	private ClusterSettings clusterSettings = DEFAULT_MONGO_SETTINGS.getClusterSettings();
-	private SocketSettings socketSettings = DEFAULT_MONGO_SETTINGS.getSocketSettings();
-	private SocketSettings heartbeatSocketSettings = DEFAULT_MONGO_SETTINGS.getHeartbeatSocketSettings();
-	private ConnectionPoolSettings connectionPoolSettings = DEFAULT_MONGO_SETTINGS.getConnectionPoolSettings();
-	private ServerSettings serverSettings = DEFAULT_MONGO_SETTINGS.getServerSettings();
-	private SslSettings sslSettings = DEFAULT_MONGO_SETTINGS.getSslSettings();
-
-	/**
-	 * Set the {@link ReadPreference}.
-	 *
-	 * @param readPreference
-	 */
-	public void setReadPreference(ReadPreference readPreference) {
-		this.readPreference = readPreference;
-	}
-
-	/**
-	 * Set the {@link WriteConcern}.
-	 *
-	 * @param writeConcern
-	 */
-	public void setWriteConcern(WriteConcern writeConcern) {
-		this.writeConcern = writeConcern;
-	}
-
-	/**
-	 * Set the {@link ReadConcern}.
-	 *
-	 * @param readConcern
-	 */
-	public void setReadConcern(ReadConcern readConcern) {
-		this.readConcern = readConcern;
-	}
-
-	/**
-	 * Set the List of {@link MongoCredential}s.
-	 *
-	 * @param credentialList must not be {@literal null}.
-	 */
-	public void setCredentialList(List<MongoCredential> credentialList) {
-
-		Assert.notNull(credentialList, "CredendialList must not be null!");
-
-		this.credentialList.addAll(credentialList);
-	}
-
-	/**
-	 * Adds the {@link MongoCredential} to the list of credentials.
-	 *
-	 * @param mongoCredential must not be {@literal null}.
-	 */
-	public void addMongoCredential(MongoCredential mongoCredential) {
-
-		Assert.notNull(mongoCredential, "MongoCredential must not be null!");
-
-		this.credentialList.add(mongoCredential);
-	}
-
-	/**
-	 * Set the {@link StreamFactoryFactory}.
-	 *
-	 * @param streamFactoryFactory
-	 */
-	public void setStreamFactoryFactory(StreamFactoryFactory streamFactoryFactory) {
-		this.streamFactoryFactory = streamFactoryFactory;
-	}
-
-	/**
-	 * Set the {@link CodecRegistry}.
-	 *
-	 * @param codecRegistry
-	 */
-	public void setCodecRegistry(CodecRegistry codecRegistry) {
-		this.codecRegistry = codecRegistry;
-	}
-
-	/**
-	 * Set the {@link ClusterSettings}.
-	 *
-	 * @param clusterSettings
-	 */
-	public void setClusterSettings(ClusterSettings clusterSettings) {
-		this.clusterSettings = clusterSettings;
-	}
-
-	/**
-	 * Set the {@link SocketSettings}.
-	 *
-	 * @param socketSettings
-	 */
-	public void setSocketSettings(SocketSettings socketSettings) {
-		this.socketSettings = socketSettings;
-	}
-
-	/**
-	 * Set the heartbeat {@link SocketSettings}.
-	 *
-	 * @param heartbeatSocketSettings
-	 */
-	public void setHeartbeatSocketSettings(SocketSettings heartbeatSocketSettings) {
-		this.heartbeatSocketSettings = heartbeatSocketSettings;
-	}
-
-	/**
-	 * Set the {@link ConnectionPoolSettings}.
-	 *
-	 * @param connectionPoolSettings
-	 */
-	public void setConnectionPoolSettings(ConnectionPoolSettings connectionPoolSettings) {
-		this.connectionPoolSettings = connectionPoolSettings;
-	}
-
-	/**
-	 * Set the {@link ServerSettings}.
-	 *
-	 * @param serverSettings
-	 */
-	public void setServerSettings(ServerSettings serverSettings) {
-		this.serverSettings = serverSettings;
-	}
-
-	/**
-	 * Set the {@link SslSettings}.
-	 *
-	 * @param sslSettings
-	 */
-	public void setSslSettings(SslSettings sslSettings) {
-		this.sslSettings = sslSettings;
-	}
-
-	@Override
-	public Class<?> getObjectType() {
-		return MongoClientSettings.class;
-	}
-
-	@Override
-	protected MongoClientSettings createInstance() throws Exception {
-
-		return MongoClientSettings.builder() //
-				.readPreference(readPreference) //
-				.writeConcern(writeConcern) //
-				.readConcern(readConcern) //
-				.credentialList(credentialList) //
-				.streamFactoryFactory(streamFactoryFactory) //
-				.codecRegistry(codecRegistry) //
-				.clusterSettings(clusterSettings) //
-				.socketSettings(socketSettings) //
-				.heartbeatSocketSettings(heartbeatSocketSettings) //
-				.connectionPoolSettings(connectionPoolSettings) //
-				.serverSettings(serverSettings) //
-				.sslSettings(sslSettings) //
-				.build();
-	}
-}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/ReactiveMongoDbUtils.java

@@ -1,51 +0,0 @@
-/*
- * Copyright 2016 the original author or authors.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-package org.springframework.data.mongodb.core;
-
-import com.mongodb.reactivestreams.client.MongoClient;
-import com.mongodb.reactivestreams.client.MongoDatabase;
-
-/**
- * Helper class featuring helper methods for internal MongoDb classes. Mainly intended for internal use within the
- * framework.
- *
- * @author Mark Paluch
- * @author Christoph Strobl
- * @since 2.0
- */
-public abstract class ReactiveMongoDbUtils {
-
-	/**
-	 * Private constructor to prevent instantiation.
-	 */
-	private ReactiveMongoDbUtils() {}
-
-	/**
-	 * Obtains a {@link MongoDatabase} connection for the given {@link MongoClient} instance and database name
-	 *
-	 * @param mongo the {@link MongoClient} instance, must not be {@literal null}.
-	 * @param databaseName the database name, must not be {@literal null} or empty.
-	 * @return the {@link MongoDatabase} connection
-	 */
-	public static MongoDatabase getMongoDatabase(MongoClient mongo, String databaseName) {
-		return doGetMongoDatabase(mongo, databaseName, true);
-	}
-
-	private static MongoDatabase doGetMongoDatabase(MongoClient mongo, String databaseName, boolean allowCreate) {
-		return mongo.getDatabase(databaseName);
-	}
-
-}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/ReactiveMongoOperations.java

@@ -1,945 +0,0 @@
-/*
- * Copyright 2016 the original author or authors.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-package org.springframework.data.mongodb.core;
-
-import java.util.Collection;
-
-import org.bson.Document;
-import org.reactivestreams.Publisher;
-import org.reactivestreams.Subscription;
-import org.springframework.data.geo.GeoResult;
-import org.springframework.data.mongodb.core.convert.MappingMongoConverter;
-import org.springframework.data.mongodb.core.convert.MongoConverter;
-import org.springframework.data.mongodb.core.query.BasicQuery;
-import org.springframework.data.mongodb.core.query.Criteria;
-import org.springframework.data.mongodb.core.query.NearQuery;
-import org.springframework.data.mongodb.core.query.Query;
-import org.springframework.data.mongodb.core.query.Update;
-
-import com.mongodb.ReadPreference;
-import com.mongodb.client.result.DeleteResult;
-import com.mongodb.client.result.UpdateResult;
-import com.mongodb.reactivestreams.client.MongoCollection;
-
-import reactor.core.publisher.Flux;
-import reactor.core.publisher.Mono;
-
-/**
- * Interface that specifies a basic set of MongoDB operations executed in a reactive way.
- * <p>
- * Implemented by {@link ReactiveMongoTemplate}. Not often used but a useful option for extensibility and testability
- * (as it can be easily mocked, stubbed, or be the target of a JDK proxy). Command execution using
- * {@link ReactiveMongoOperations} is deferred until subscriber subscribes to the {@link Publisher}.
- *
- * @author Mark Paluch
- * @author Christoph Strobl
- * @see Flux
- * @see Mono
- * @see http://projectreactor.io/docs/
- * @since 2.0
- */
-public interface ReactiveMongoOperations {
-
-	/**
-	 * Returns the reactive operations that can be performed on indexes
-	 *
-	 * @return index operations on the named collection
-	 */
-	ReactiveIndexOperations indexOps(String collectionName);
-
-	/**
-	 * Returns the reactive operations that can be performed on indexes
-	 *
-	 * @return index operations on the named collection associated with the given entity class
-	 */
-	ReactiveIndexOperations indexOps(Class<?> entityClass);
-
-	/**
-	 * Execute the a MongoDB command expressed as a JSON string. This will call the method JSON.parse that is part of the
-	 * MongoDB driver to convert the JSON string to a DBObject. Any errors that result from executing this command will be
-	 * converted into Spring's DAO exception hierarchy.
-	 *
-	 * @param jsonCommand a MongoDB command expressed as a JSON string.
-	 * @return a result object returned by the action
-	 */
-	Mono<Document> executeCommand(String jsonCommand);
-
-	/**
-	 * Execute a MongoDB command. Any errors that result from executing this command will be converted into Spring's DAO
-	 * exception hierarchy.
-	 *
-	 * @param command a MongoDB command
-	 * @return a result object returned by the action
-	 */
-	Mono<Document> executeCommand(Document command);
-
-	/**
-	 * Execute a MongoDB command. Any errors that result from executing this command will be converted into Spring's data
-	 * access exception hierarchy.
-	 *
-	 * @param command a MongoDB command, must not be {@literal null}.
-	 * @param readPreference read preferences to use, can be {@literal null}.
-	 * @return a result object returned by the action
-	 */
-	Mono<Document> executeCommand(Document command, ReadPreference readPreference);
-
-	/**
-	 * Executes a {@link ReactiveDatabaseCallback} translating any exceptions as necessary.
-	 * <p/>
-	 * Allows for returning a result object, that is a domain object or a collection of domain objects.
-	 *
-	 * @param <T> return type
-	 * @param action callback object that specifies the MongoDB actions to perform on the passed in DB instance.
-	 * @return a result object returned by the action
-	 */
-	<T> Flux<T> execute(ReactiveDatabaseCallback<T> action);
-
-	/**
-	 * Executes the given {@link ReactiveCollectionCallback} on the entity collection of the specified class.
-	 * <p/>
-	 * Allows for returning a result object, that is a domain object or a collection of domain objects.
-	 *
-	 * @param entityClass class that determines the collection to use
-	 * @param <T> return type
-	 * @param action callback object that specifies the MongoDB action
-	 * @return a result object returned by the action or <tt>null</tt>
-	 */
-	<T> Flux<T> execute(Class<?> entityClass, ReactiveCollectionCallback<T> action);
-
-	/**
-	 * Executes the given {@link ReactiveCollectionCallback} on the collection of the given name.
-	 * <p/>
-	 * Allows for returning a result object, that is a domain object or a collection of domain objects.
-	 *
-	 * @param <T> return type
-	 * @param collectionName the name of the collection that specifies which DBCollection instance will be passed into
-	 * @param action callback object that specifies the MongoDB action the callback action.
-	 * @return a result object returned by the action or <tt>null</tt>
-	 */
-	<T> Flux<T> execute(String collectionName, ReactiveCollectionCallback<T> action);
-
-	/**
-	 * Create an uncapped collection with a name based on the provided entity class.
-	 *
-	 * @param entityClass class that determines the collection to create
-	 * @return the created collection
-	 */
-	<T> Mono<MongoCollection<Document>> createCollection(Class<T> entityClass);
-
-	/**
-	 * Create a collection with a name based on the provided entity class using the options.
-	 *
-	 * @param entityClass class that determines the collection to create
-	 * @param collectionOptions options to use when creating the collection.
-	 * @return the created collection
-	 */
-	<T> Mono<MongoCollection<Document>> createCollection(Class<T> entityClass, CollectionOptions collectionOptions);
-
-	/**
-	 * Create an uncapped collection with the provided name.
-	 *
-	 * @param collectionName name of the collection
-	 * @return the created collection
-	 */
-	Mono<MongoCollection<Document>> createCollection(String collectionName);
-
-	/**
-	 * Create a collection with the provided name and options.
-	 *
-	 * @param collectionName name of the collection
-	 * @param collectionOptions options to use when creating the collection.
-	 * @return the created collection
-	 */
-	Mono<MongoCollection<Document>> createCollection(String collectionName, CollectionOptions collectionOptions);
-
-	/**
-	 * A set of collection names.
-	 *
-	 * @return Flux of collection names
-	 */
-	Flux<String> getCollectionNames();
-
-	/**
-	 * Get a collection by name, creating it if it doesn't exist.
-	 * <p/>
-	 * Translate any exceptions as necessary.
-	 *
-	 * @param collectionName name of the collection
-	 * @return an existing collection or a newly created one.
-	 */
-	MongoCollection<Document> getCollection(String collectionName);
-
-	/**
-	 * Check to see if a collection with a name indicated by the entity class exists.
-	 * <p/>
-	 * Translate any exceptions as necessary.
-	 *
-	 * @param entityClass class that determines the name of the collection
-	 * @return true if a collection with the given name is found, false otherwise.
-	 */
-	<T> Mono<Boolean> collectionExists(Class<T> entityClass);
-
-	/**
-	 * Check to see if a collection with a given name exists.
-	 * <p/>
-	 * Translate any exceptions as necessary.
-	 *
-	 * @param collectionName name of the collection
-	 * @return true if a collection with the given name is found, false otherwise.
-	 */
-	Mono<Boolean> collectionExists(String collectionName);
-
-	/**
-	 * Drop the collection with the name indicated by the entity class.
-	 * <p/>
-	 * Translate any exceptions as necessary.
-	 *
-	 * @param entityClass class that determines the collection to drop/delete.
-	 */
-	<T> Mono<Void> dropCollection(Class<T> entityClass);
-
-	/**
-	 * Drop the collection with the given name.
-	 * <p/>
-	 * Translate any exceptions as necessary.
-	 *
-	 * @param collectionName name of the collection to drop/delete.
-	 */
-	Mono<Void> dropCollection(String collectionName);
-
-	/**
-	 * Query for a {@link Flux} of objects of type T from the collection used by the entity class.
-	 * <p/>
-	 * The object is converted from the MongoDB native representation using an instance of {@see MongoConverter}. Unless
-	 * configured otherwise, an instance of {@link MappingMongoConverter} will be used.
-	 * <p/>
-	 * If your collection does not contain a homogeneous collection of types, this operation will not be an efficient way
-	 * to map objects since the test for class type is done in the client and not on the server.
-	 * @param entityClass the parametrized type of the returned {@link Flux}.
-	 *
-	 * @return the converted collection
-	 */
-	<T> Flux<T> findAll(Class<T> entityClass);
-
-	/**
-	 * Query for a {@link Flux} of objects of type T from the specified collection.
-	 * <p/>
-	 * The object is converted from the MongoDB native representation using an instance of {@see MongoConverter}. Unless
-	 * configured otherwise, an instance of {@link MappingMongoConverter} will be used.
-	 * <p/>
-	 * If your collection does not contain a homogeneous collection of types, this operation will not be an efficient way
-	 * to map objects since the test for class type is done in the client and not on the server.
-	 *
-	 * @param entityClass the parametrized type of the returned {@link Flux}.
-	 * @param collectionName name of the collection to retrieve the objects from
-	 * @return the converted collection
-	 */
-	<T> Flux<T> findAll(Class<T> entityClass, String collectionName);
-
-	/**
-	 * Map the results of an ad-hoc query on the collection for the entity class to a single instance of an object of the
-	 * specified type.
-	 * <p/>
-	 * The object is converted from the MongoDB native representation using an instance of {@see MongoConverter}. Unless
-	 * configured otherwise, an instance of {@link MappingMongoConverter} will be used.
-	 * <p/>
-	 * The query is specified as a {@link Query} which can be created either using the {@link BasicQuery} or the more
-	 * feature rich {@link Query}.
-	 *
-	 * @param query the query class that specifies the criteria used to find a record and also an optional fields
-	 *          specification
-	 * @param entityClass the parametrized type of the returned {@link Mono}.
-	 * @return the converted object
-	 */
-	<T> Mono<T> findOne(Query query, Class<T> entityClass);
-
-	/**
-	 * Map the results of an ad-hoc query on the specified collection to a single instance of an object of the specified
-	 * type.
-	 * <p/>
-	 * The object is converted from the MongoDB native representation using an instance of {@see MongoConverter}. Unless
-	 * configured otherwise, an instance of {@link MappingMongoConverter} will be used.
-	 * <p/>
-	 * The query is specified as a {@link Query} which can be created either using the {@link BasicQuery} or the more
-	 * feature rich {@link Query}.
-	 *
-	 * @param query the query class that specifies the criteria used to find a record and also an optional fields
-	 *          specification
-	 * @param entityClass the parametrized type of the returned {@link Mono}.
-	 * @param collectionName name of the collection to retrieve the objects from
-	 * @return the converted object
-	 */
-	<T> Mono<T> findOne(Query query, Class<T> entityClass, String collectionName);
-
-	/**
-	 * Determine result of given {@link Query} contains at least one element.
-	 *
-	 * @param query the {@link Query} class that specifies the criteria used to find a record.
-	 * @param collectionName name of the collection to check for objects.
-	 * @return
-	 */
-	Mono<Boolean> exists(Query query, String collectionName);
-
-	/**
-	 * Determine result of given {@link Query} contains at least one element.
-	 *
-	 * @param query the {@link Query} class that specifies the criteria used to find a record.
-	 * @param entityClass the parametrized type.
-	 * @return
-	 */
-	Mono<Boolean> exists(Query query, Class<?> entityClass);
-
-	/**
-	 * Determine result of given {@link Query} contains at least one element.
-	 *
-	 * @param query the {@link Query} class that specifies the criteria used to find a record.
-	 * @param entityClass the parametrized type.
-	 * @param collectionName name of the collection to check for objects.
-	 * @return
-	 */
-	Mono<Boolean> exists(Query query, Class<?> entityClass, String collectionName);
-
-	/**
-	 * Map the results of an ad-hoc query on the collection for the entity class to a {@link Flux} of the specified type.
-	 * <p/>
-	 * The object is converted from the MongoDB native representation using an instance of {@see MongoConverter}. Unless
-	 * configured otherwise, an instance of {@link MappingMongoConverter} will be used.
-	 * <p/>
-	 * The query is specified as a {@link Query} which can be created either using the {@link BasicQuery} or the more
-	 * feature rich {@link Query}.
-	 *
-	 * @param query the query class that specifies the criteria used to find a record and also an optional fields
-	 *          specification
-	 * @param entityClass the parametrized type of the returned {@link Flux}.
-	 * @return the {@link Flux} of converted objects
-	 */
-	<T> Flux<T> find(Query query, Class<T> entityClass);
-
-	/**
-	 * Map the results of an ad-hoc query on the specified collection to a {@link Flux} of the specified type.
-	 * <p/>
-	 * The object is converted from the MongoDB native representation using an instance of {@see MongoConverter}. Unless
-	 * configured otherwise, an instance of {@link MappingMongoConverter} will be used.
-	 * <p/>
-	 * The query is specified as a {@link Query} which can be created either using the {@link BasicQuery} or the more
-	 * feature rich {@link Query}.
-	 *
-	 * @param query the query class that specifies the criteria used to find a record and also an optional fields
-	 *          specification
-	 * @param entityClass the parametrized type of the returned {@link Flux}.
-	 * @param collectionName name of the collection to retrieve the objects from
-	 * @return the {@link Flux} of converted objects
-	 */
-	<T> Flux<T> find(Query query, Class<T> entityClass, String collectionName);
-
-	/**
-	 * Returns a document with the given id mapped onto the given class. The collection the query is ran against will be
-	 * derived from the given target class as well.
-	 *
-	 * @param <T>
-	 * @param id the id of the document to return.
-	 * @param entityClass the type the document shall be converted into.
-	 * @return the document with the given id mapped onto the given target class.
-	 */
-	<T> Mono<T> findById(Object id, Class<T> entityClass);
-
-	/**
-	 * Returns the document with the given id from the given collection mapped onto the given target class.
-	 *
-	 * @param id the id of the document to return
-	 * @param entityClass the type to convert the document to
-	 * @param collectionName the collection to query for the document
-	 * @param <T>
-	 * @return
-	 */
-	<T> Mono<T> findById(Object id, Class<T> entityClass, String collectionName);
-
-	/**
-	 * Returns {@link Flux} of {@link GeoResult} for all entities matching the given {@link NearQuery}. Will consider entity mapping
-	 * information to determine the collection the query is ran against. Note, that MongoDB limits the number of results
-	 * by default. Make sure to add an explicit limit to the {@link NearQuery} if you expect a particular number of
-	 * results.
-	 *
-	 * @param near must not be {@literal null}.
-	 * @param entityClass must not be {@literal null}.
-	 * @return
-	 */
-	<T> Flux<GeoResult<T>> geoNear(NearQuery near, Class<T> entityClass);
-
-	/**
-	 * Returns {@link Flux} of {@link GeoResult} for all entities matching the given {@link NearQuery}. Note, that MongoDB limits the
-	 * number of results by default. Make sure to add an explicit limit to the {@link NearQuery} if you expect a
-	 * particular number of results.
-	 *
-	 * @param near must not be {@literal null}.
-	 * @param entityClass must not be {@literal null}.
-	 * @param collectionName the collection to trigger the query against. If no collection name is given the entity class
-	 *          will be inspected.
-	 * @return
-	 */
-	<T> Flux<GeoResult<T>> geoNear(NearQuery near, Class<T> entityClass, String collectionName);
-
-	/**
-	 * Triggers <a href="http://docs.mongodb.org/manual/reference/method/db.collection.findAndModify/">findAndModify <a/>
-	 * to apply provided {@link Update} on documents matching {@link Criteria} of given {@link Query}.
-	 *
-	 * @param query the {@link Query} class that specifies the {@link Criteria} used to find a record and also an optional
-	 *          fields specification.
-	 * @param update the {@link Update} to apply on matching documents.
-	 * @param entityClass the parametrized type.
-	 * @return
-	 */
-	<T> Mono<T> findAndModify(Query query, Update update, Class<T> entityClass);
-
-	/**
-	 * Triggers <a href="http://docs.mongodb.org/manual/reference/method/db.collection.findAndModify/">findAndModify <a/>
-	 * to apply provided {@link Update} on documents matching {@link Criteria} of given {@link Query}.
-	 *
-	 * @param query the {@link Query} class that specifies the {@link Criteria} used to find a record and also an optional
-	 *          fields specification.
-	 * @param update the {@link Update} to apply on matching documents.
-	 * @param entityClass the parametrized type.
-	 * @param collectionName the collection to query.
-	 * @return
-	 */
-	<T> Mono<T> findAndModify(Query query, Update update, Class<T> entityClass, String collectionName);
-
-	/**
-	 * Triggers <a href="http://docs.mongodb.org/manual/reference/method/db.collection.findAndModify/">findAndModify <a/>
-	 * to apply provided {@link Update} on documents matching {@link Criteria} of given {@link Query} taking
-	 * {@link FindAndModifyOptions} into account.
-	 *
-	 * @param query the {@link Query} class that specifies the {@link Criteria} used to find a record and also an optional
-	 *          fields specification.
-	 * @param update the {@link Update} to apply on matching documents.
-	 * @param options the {@link FindAndModifyOptions} holding additional information.
-	 * @param entityClass the parametrized type.
-	 * @return
-	 */
-	<T> Mono<T> findAndModify(Query query, Update update, FindAndModifyOptions options, Class<T> entityClass);
-
-	/**
-	 * Triggers <a href="http://docs.mongodb.org/manual/reference/method/db.collection.findAndModify/">findAndModify <a/>
-	 * to apply provided {@link Update} on documents matching {@link Criteria} of given {@link Query} taking
-	 * {@link FindAndModifyOptions} into account.
-	 *
-	 * @param query the {@link Query} class that specifies the {@link Criteria} used to find a record and also an optional
-	 *          fields specification.
-	 * @param update the {@link Update} to apply on matching documents.
-	 * @param options the {@link FindAndModifyOptions} holding additional information.
-	 * @param entityClass the parametrized type.
-	 * @param collectionName the collection to query.
-	 * @return
-	 */
-	<T> Mono<T> findAndModify(Query query, Update update, FindAndModifyOptions options, Class<T> entityClass,
-			String collectionName);
-
-	/**
-	 * Map the results of an ad-hoc query on the collection for the entity type to a single instance of an object of the
-	 * specified type. The first document that matches the query is returned and also removed from the collection in the
-	 * database.
-	 * <p/>
-	 * The object is converted from the MongoDB native representation using an instance of {@see MongoConverter}.
-	 * <p/>
-	 * The query is specified as a {@link Query} which can be created either using the {@link BasicQuery} or the more
-	 * feature rich {@link Query}.
-	 *
-	 * @param query the query class that specifies the criteria used to find a record and also an optional fields
-	 *          specification
-	 * @param entityClass the parametrized type of the returned {@link Mono}.
-	 * @return the converted object
-	 */
-	<T> Mono<T> findAndRemove(Query query, Class<T> entityClass);
-
-	/**
-	 * Map the results of an ad-hoc query on the specified collection to a single instance of an object of the specified
-	 * type. The first document that matches the query is returned and also removed from the collection in the database.
-	 * <p/>
-	 * The object is converted from the MongoDB native representation using an instance of {@see MongoConverter}. Unless
-	 * configured otherwise, an instance of {@link MappingMongoConverter} will be used.
-	 * <p/>
-	 * The query is specified as a {@link Query} which can be created either using the {@link BasicQuery} or the more
-	 * feature rich {@link Query}.
-	 *
-	 * @param query the query class that specifies the criteria used to find a record and also an optional fields
-	 *          specification
-	 * @param entityClass the parametrized type of the returned {@link Mono}.
-	 * @param collectionName name of the collection to retrieve the objects from.
-	 * @return the converted object
-	 */
-	<T> Mono<T> findAndRemove(Query query, Class<T> entityClass, String collectionName);
-
-	/**
-	 * Returns the number of documents for the given {@link Query} by querying the collection of the given entity class.
-	 *
-	 * @param query
-	 * @param entityClass must not be {@literal null}.
-	 * @return
-	 */
-	Mono<Long> count(Query query, Class<?> entityClass);
-
-	/**
-	 * Returns the number of documents for the given {@link Query} querying the given collection. The given {@link Query}
-	 * must solely consist of document field references as we lack type information to map potential property references
-	 * onto document fields. TO make sure the query gets mapped, use {@link #count(Query, Class, String)}.
-	 *
-	 * @param query
-	 * @param collectionName must not be {@literal null} or empty.
-	 * @return
-	 * @see #count(Query, Class, String)
-	 */
-	Mono<Long> count(Query query, String collectionName);
-
-	/**
-	 * Returns the number of documents for the given {@link Query} by querying the given collection using the given entity
-	 * class to map the given {@link Query}.
-	 *
-	 * @param query
-	 * @param entityClass must not be {@literal null}.
-	 * @param collectionName must not be {@literal null} or empty.
-	 * @return
-	 */
-	Mono<Long> count(Query query, Class<?> entityClass, String collectionName);
-
-	/**
-	 * Insert the object into the collection for the entity type of the object to save.
-	 * <p/>
-	 * The object is converted to the MongoDB native representation using an instance of {@see MongoConverter}.
-	 * <p/>
-	 * If you object has an "Id' property, it will be set with the generated Id from MongoDB. If your Id property is a
-	 * String then MongoDB ObjectId will be used to populate that string. Otherwise, the conversion from ObjectId to your
-	 * property type will be handled by Spring's BeanWrapper class that leverages Type Conversion API. See
-	 * <a href="http://docs.spring.io/spring/docs/current/spring-framework-reference/html/validation.html#core-convert" >
-	 * Spring's Type Conversion"</a> for more details.
-	 * <p/>
-	 * <p/>
-	 * Insert is used to initially store the object into the database. To update an existing object use the save method.
-	 *
-	 * @param objectToSave the object to store in the collection.
-	 * @return
-	 */
-	<T> Mono<T> insert(T objectToSave);
-
-	/**
-	 * Insert the object into the specified collection.
-	 * <p/>
-	 * The object is converted to the MongoDB native representation using an instance of {@see MongoConverter}. Unless
-	 * configured otherwise, an instance of {@link MappingMongoConverter} will be used.
-	 * <p/>
-	 * Insert is used to initially store the object into the database. To update an existing object use the save method.
-	 *
-	 * @param objectToSave the object to store in the collection
-	 * @param collectionName name of the collection to store the object in
-	 * @return
-	 */
-	<T> Mono<T> insert(T objectToSave, String collectionName);
-
-	/**
-	 * Insert a Collection of objects into a collection in a single batch write to the database.
-	 *
-	 * @param batchToSave the batch of objects to save.
-	 * @param entityClass class that determines the collection to use
-	 * @return
-	 */
-	<T> Flux<T> insert(Collection<? extends T> batchToSave, Class<?> entityClass);
-
-	/**
-	 * Insert a batch of objects into the specified collection in a single batch write to the database.
-	 *
-	 * @param batchToSave the list of objects to save.
-	 * @param collectionName name of the collection to store the object in
-	 * @return
-	 */
-	<T> Flux<T> insert(Collection<? extends T> batchToSave, String collectionName);
-
-	/**
-	 * Insert a mixed Collection of objects into a database collection determining the collection name to use based on the
-	 * class.
-	 *
-	 * @param objectsToSave the list of objects to save.
-	 * @return
-	 */
-	<T> Flux<T> insertAll(Collection<? extends T> objectsToSave);
-
-	/**
-	 * Insert the object into the collection for the entity type of the object to save.
-	 * <p/>
-	 * The object is converted to the MongoDB native representation using an instance of {@see MongoConverter}.
-	 * <p/>
-	 * If you object has an "Id' property, it will be set with the generated Id from MongoDB. If your Id property is a
-	 * String then MongoDB ObjectId will be used to populate that string. Otherwise, the conversion from ObjectId to your
-	 * property type will be handled by Spring's BeanWrapper class that leverages Type Conversion API. See
-	 * <a href="http://docs.spring.io/spring/docs/current/spring-framework-reference/html/validation.html#core-convert" >
-	 * Spring's Type Conversion"</a> for more details.
-	 * <p/>
-	 * <p/>
-	 * Insert is used to initially store the object into the database. To update an existing object use the save method.
-	 *
-	 * @param objectToSave the object to store in the collection.
-	 * @return
-	 */
-	<T> Mono<T> insert(Mono<? extends T> objectToSave);
-
-	/**
-	 * Insert a Collection of objects into a collection in a single batch write to the database.
-	 *
-	 * @param batchToSave the publisher which provides objects to save.
-	 * @param entityClass class that determines the collection to use
-	 * @return
-	 */
-	<T> Flux<T> insertAll(Mono<? extends Collection<? extends T>> batchToSave, Class<?> entityClass);
-
-	/**
-	 * Insert objects into the specified collection in a single batch write to the database.
-	 *
-	 * @param batchToSave the publisher which provides objects to save.
-	 * @param collectionName name of the collection to store the object in
-	 * @return
-	 */
-	<T> Flux<T> insertAll(Mono<? extends Collection<? extends T>> batchToSave, String collectionName);
-
-	/**
-	 * Insert a mixed Collection of objects into a database collection determining the collection name to use based on the
-	 * class.
-	 *
-	 * @param objectsToSave the publisher which provides objects to save.
-	 * @return
-	 */
-	<T> Flux<T> insertAll(Mono<? extends Collection<? extends T>> objectsToSave);
-
-	/**
-	 * Save the object to the collection for the entity type of the object to save. This will perform an insert if the
-	 * object is not already present, that is an 'upsert'.
-	 * <p/>
-	 * The object is converted to the MongoDB native representation using an instance of {@see MongoConverter}. Unless
-	 * configured otherwise, an instance of {@link MappingMongoConverter} will be used.
-	 * <p/>
-	 * If you object has an "Id' property, it will be set with the generated Id from MongoDB. If your Id property is a
-	 * String then MongoDB ObjectId will be used to populate that string. Otherwise, the conversion from ObjectId to your
-	 * property type will be handled by Spring's BeanWrapper class that leverages Type Conversion API. See
-	 * <a href="http://docs.spring.io/spring/docs/current/spring-framework-reference/html/validation.html#core-convert" >
-	 * Spring's Type Conversion"</a> for more details.
-	 *
-	 * @param objectToSave the object to store in the collection
-	 * @return
-	 */
-	<T> Mono<T> save(T objectToSave);
-
-	/**
-	 * Save the object to the specified collection. This will perform an insert if the object is not already present, that
-	 * is an 'upsert'.
-	 * <p/>
-	 * The object is converted to the MongoDB native representation using an instance of {@see MongoConverter}. Unless
-	 * configured otherwise, an instance of {@link MappingMongoConverter} will be used.
-	 * <p/>
-	 * If you object has an "Id' property, it will be set with the generated Id from MongoDB. If your Id property is a
-	 * String then MongoDB ObjectId will be used to populate that string. Otherwise, the conversion from ObjectId to your
-	 * property type will be handled by Spring's BeanWrapper class that leverages Type Conversion API. See <a
-	 * http://docs.spring.io/spring/docs/current/spring-framework-reference/html/validation.html#core-convert">Spring's
-	 * Type Conversion"</a> for more details.
-	 *
-	 * @param objectToSave the object to store in the collection
-	 * @param collectionName name of the collection to store the object in
-	 * @return
-	 */
-	<T> Mono<T> save(T objectToSave, String collectionName);
-
-	/**
-	 * Save the object to the collection for the entity type of the object to save. This will perform an insert if the
-	 * object is not already present, that is an 'upsert'.
-	 * <p/>
-	 * The object is converted to the MongoDB native representation using an instance of {@see MongoConverter}. Unless
-	 * configured otherwise, an instance of {@link MappingMongoConverter} will be used.
-	 * <p/>
-	 * If you object has an "Id' property, it will be set with the generated Id from MongoDB. If your Id property is a
-	 * String then MongoDB ObjectId will be used to populate that string. Otherwise, the conversion from ObjectId to your
-	 * property type will be handled by Spring's BeanWrapper class that leverages Type Conversion API. See
-	 * <a href="http://docs.spring.io/spring/docs/current/spring-framework-reference/html/validation.html#core-convert" >
-	 * Spring's Type Conversion"</a> for more details.
-	 *
-	 * @param objectToSave the object to store in the collection
-	 * @return
-	 */
-	<T> Mono<T> save(Mono<? extends T> objectToSave);
-
-	/**
-	 * Save the object to the specified collection. This will perform an insert if the object is not already present, that
-	 * is an 'upsert'.
-	 * <p/>
-	 * The object is converted to the MongoDB native representation using an instance of {@see MongoConverter}. Unless
-	 * configured otherwise, an instance of {@link MappingMongoConverter} will be used.
-	 * <p/>
-	 * If you object has an "Id' property, it will be set with the generated Id from MongoDB. If your Id property is a
-	 * String then MongoDB ObjectId will be used to populate that string. Otherwise, the conversion from ObjectId to your
-	 * property type will be handled by Spring's BeanWrapper class that leverages Type Conversion API. See <a
-	 * http://docs.spring.io/spring/docs/current/spring-framework-reference/html/validation.html#core-convert">Spring's
-	 * Type Conversion"</a> for more details.
-	 *
-	 * @param objectToSave the object to store in the collection
-	 * @param collectionName name of the collection to store the object in
-	 * @return
-	 */
-	<T> Mono<T> save(Mono<? extends T> objectToSave, String collectionName);
-
-	/**
-	 * Performs an upsert. If no document is found that matches the query, a new document is created and inserted by
-	 * combining the query document and the update document.
-	 *
-	 * @param query the query document that specifies the criteria used to select a record to be upserted
-	 * @param update the update document that contains the updated object or $ operators to manipulate the existing object
-	 * @param entityClass class that determines the collection to use
-	 * @return the WriteResult which lets you access the results of the previous write.
-	 */
-	Mono<UpdateResult> upsert(Query query, Update update, Class<?> entityClass);
-
-	/**
-	 * Performs an upsert. If no document is found that matches the query, a new document is created and inserted by
-	 * combining the query document and the update document.
-	 *
-	 * @param query the query document that specifies the criteria used to select a record to be updated
-	 * @param update the update document that contains the updated object or $ operators to manipulate the existing
-	 *          object.
-	 * @param collectionName name of the collection to update the object in
-	 * @return the WriteResult which lets you access the results of the previous write.
-	 */
-	Mono<UpdateResult> upsert(Query query, Update update, String collectionName);
-
-	/**
-	 * Performs an upsert. If no document is found that matches the query, a new document is created and inserted by
-	 * combining the query document and the update document.
-	 *
-	 * @param query the query document that specifies the criteria used to select a record to be upserted
-	 * @param update the update document that contains the updated object or $ operators to manipulate the existing object
-	 * @param entityClass class of the pojo to be operated on
-	 * @param collectionName name of the collection to update the object in
-	 * @return the WriteResult which lets you access the results of the previous write.
-	 */
-	Mono<UpdateResult> upsert(Query query, Update update, Class<?> entityClass, String collectionName);
-
-	/**
-	 * Updates the first object that is found in the collection of the entity class that matches the query document with
-	 * the provided update document.
-	 *
-	 * @param query the query document that specifies the criteria used to select a record to be updated
-	 * @param update the update document that contains the updated object or $ operators to manipulate the existing
-	 *          object.
-	 * @param entityClass class that determines the collection to use
-	 * @return the WriteResult which lets you access the results of the previous write.
-	 */
-	Mono<UpdateResult> updateFirst(Query query, Update update, Class<?> entityClass);
-
-	/**
-	 * Updates the first object that is found in the specified collection that matches the query document criteria with
-	 * the provided updated document.
-	 *
-	 * @param query the query document that specifies the criteria used to select a record to be updated
-	 * @param update the update document that contains the updated object or $ operators to manipulate the existing
-	 *          object.
-	 * @param collectionName name of the collection to update the object in
-	 * @return the WriteResult which lets you access the results of the previous write.
-	 */
-	Mono<UpdateResult> updateFirst(Query query, Update update, String collectionName);
-
-	/**
-	 * Updates the first object that is found in the specified collection that matches the query document criteria with
-	 * the provided updated document.
-	 *
-	 * @param query the query document that specifies the criteria used to select a record to be updated
-	 * @param update the update document that contains the updated object or $ operators to manipulate the existing
-	 *          object.
-	 * @param entityClass class of the pojo to be operated on
-	 * @param collectionName name of the collection to update the object in
-	 * @return the WriteResult which lets you access the results of the previous write.
-	 */
-	Mono<UpdateResult> updateFirst(Query query, Update update, Class<?> entityClass, String collectionName);
-
-	/**
-	 * Updates all objects that are found in the collection for the entity class that matches the query document criteria
-	 * with the provided updated document.
-	 *
-	 * @param query the query document that specifies the criteria used to select a record to be updated
-	 * @param update the update document that contains the updated object or $ operators to manipulate the existing
-	 *          object.
-	 * @param entityClass class that determines the collection to use
-	 * @return the WriteResult which lets you access the results of the previous write.
-	 */
-	Mono<UpdateResult> updateMulti(Query query, Update update, Class<?> entityClass);
-
-	/**
-	 * Updates all objects that are found in the specified collection that matches the query document criteria with the
-	 * provided updated document.
-	 *
-	 * @param query the query document that specifies the criteria used to select a record to be updated
-	 * @param update the update document that contains the updated object or $ operators to manipulate the existing
-	 *          object.
-	 * @param collectionName name of the collection to update the object in
-	 * @return the WriteResult which lets you access the results of the previous write.
-	 */
-	Mono<UpdateResult> updateMulti(Query query, Update update, String collectionName);
-
-	/**
-	 * Updates all objects that are found in the collection for the entity class that matches the query document criteria
-	 * with the provided updated document.
-	 *
-	 * @param query the query document that specifies the criteria used to select a record to be updated
-	 * @param update the update document that contains the updated object or $ operators to manipulate the existing
-	 *          object.
-	 * @param entityClass class of the pojo to be operated on
-	 * @param collectionName name of the collection to update the object in
-	 * @return the WriteResult which lets you access the results of the previous write.
-	 */
-	Mono<UpdateResult> updateMulti(final Query query, final Update update, Class<?> entityClass, String collectionName);
-
-	/**
-	 * Remove the given object from the collection by id.
-	 *
-	 * @param object
-	 * @return
-	 */
-	Mono<DeleteResult> remove(Object object);
-
-	/**
-	 * Removes the given object from the given collection.
-	 *
-	 * @param object
-	 * @param collection must not be {@literal null} or empty.
-	 */
-	Mono<DeleteResult> remove(Object object, String collection);
-
-	/**
-	 * Remove the given object from the collection by id.
-	 *
-	 * @param objectToRemove
-	 * @return
-	 */
-	Mono<DeleteResult> remove(Mono<? extends Object> objectToRemove);
-
-	/**
-	 * Removes the given object from the given collection.
-	 *
-	 * @param objectToRemove
-	 * @param collection must not be {@literal null} or empty.
-	 * @return
-	 */
-	Mono<DeleteResult> remove(Mono<? extends Object> objectToRemove, String collection);
-
-	/**
-	 * Remove all documents that match the provided query document criteria from the the collection used to store the
-	 * entityClass. The Class parameter is also used to help convert the Id of the object if it is present in the query.
-	 *
-	 * @param query
-	 * @param entityClass
-	 * @return
-	 */
-	Mono<DeleteResult> remove(Query query, Class<?> entityClass);
-
-	/**
-	 * Remove all documents that match the provided query document criteria from the the collection used to store the
-	 * entityClass. The Class parameter is also used to help convert the Id of the object if it is present in the query.
-	 *
-	 * @param query
-	 * @param entityClass
-	 * @param collectionName
-	 * @return
-	 */
-	Mono<DeleteResult> remove(Query query, Class<?> entityClass, String collectionName);
-
-	/**
-	 * Remove all documents from the specified collection that match the provided query document criteria. There is no
-	 * conversion/mapping done for any criteria using the id field.
-	 *
-	 * @param query the query document that specifies the criteria used to remove a record
-	 * @param collectionName name of the collection where the objects will removed
-	 */
-	Mono<DeleteResult> remove(Query query, String collectionName);
-
-	/**
-	 * Returns and removes all documents form the specified collection that match the provided query.
-	 *
-	 * @param query
-	 * @param collectionName
-	 * @return
-	 */
-	<T> Flux<T> findAllAndRemove(Query query, String collectionName);
-
-	/**
-	 * Returns and removes all documents matching the given query form the collection used to store the entityClass.
-	 *
-	 * @param query
-	 * @param entityClass
-	 * @return
-	 */
-	<T> Flux<T> findAllAndRemove(Query query, Class<T> entityClass);
-
-	/**
-	 * Returns and removes all documents that match the provided query document criteria from the the collection used to
-	 * store the entityClass. The Class parameter is also used to help convert the Id of the object if it is present in
-	 * the query.
-	 *
-	 * @param query
-	 * @param entityClass
-	 * @param collectionName
-	 * @return
-	 */
-	<T> Flux<T> findAllAndRemove(Query query, Class<T> entityClass, String collectionName);
-
-	/**
-	 * Map the results of an ad-hoc query on the collection for the entity class to a stream of objects of the specified
-	 * type. The stream uses a {@link com.mongodb.CursorType#TailableAwait tailable} cursor that may be an infinite
-	 * stream. The stream will not be completed unless the {@link org.reactivestreams.Subscription} is
-	 * {@link Subscription#cancel() canceled}.
-	 * <p/>
-	 * The object is converted from the MongoDB native representation using an instance of {@see MongoConverter}. Unless
-	 * configured otherwise, an instance of {@link MappingMongoConverter} will be used.
-	 * <p/>
-	 * The query is specified as a {@link Query} which can be created either using the {@link BasicQuery} or the more
-	 * feature rich {@link Query}.
-	 *
-	 * @param query the query class that specifies the criteria used to find a record and also an optional fields
-	 *          specification
-	 * @param entityClass the parametrized type of the returned {@link Flux}.
-	 * @return the {@link Flux} of converted objects
-	 */
-	<T> Flux<T> tail(Query query, Class<T> entityClass);
-
-	/**
-	 * Map the results of an ad-hoc query on the collection for the entity class to a stream of objects of the specified
-	 * type. The stream uses a {@link com.mongodb.CursorType#TailableAwait tailable} cursor that may be an infinite
-	 * stream. The stream will not be completed unless the {@link org.reactivestreams.Subscription} is
-	 * {@link Subscription#cancel() canceled}.
-	 * <p/>
-	 * The object is converted from the MongoDB native representation using an instance of {@see MongoConverter}. Unless
-	 * configured otherwise, an instance of {@link MappingMongoConverter} will be used.
-	 * <p/>
-	 * The query is specified as a {@link Query} which can be created either using the {@link BasicQuery} or the more
-	 * feature rich {@link Query}.
-	 *
-	 * @param query the query class that specifies the criteria used to find a record and also an optional fields
-	 *          specification
-	 * @param entityClass the parametrized type of the returned {@link Flux}.
-	 * @param collectionName name of the collection to retrieve the objects from
-	 * @return the {@link Flux} of converted objects
-	 */
-	<T> Flux<T> tail(Query query, Class<T> entityClass, String collectionName);
-
-	/**
-	 * Returns the underlying {@link MongoConverter}.
-	 *
-	 * @return
-	 */
-	MongoConverter getConverter();
-
-}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/ReflectiveDBCollectionInvoker.java

@@ -20,10 +20,10 @@ import static org.springframework.util.ReflectionUtils.*;
 
 import java.lang.reflect.Method;
 
-import org.bson.Document;
 import org.springframework.data.mongodb.util.MongoClientVersion;
 
 import com.mongodb.DBCollection;
+import com.mongodb.DBObject;
 
 /**
  * {@link ReflectiveDBCollectionInvoker} provides reflective access to {@link DBCollection} API that is not consistently
@@ -40,7 +40,7 @@ class ReflectiveDBCollectionInvoker {
 
 	static {
 
-		GEN_INDEX_NAME_METHOD = findMethod(DBCollection.class, "genIndexName", Document.class);
+		GEN_INDEX_NAME_METHOD = findMethod(DBCollection.class, "genIndexName", DBObject.class);
 		RESET_INDEX_CHACHE_METHOD = findMethod(DBCollection.class, "resetIndexCache");
 	}
 
@@ -53,7 +53,7 @@ class ReflectiveDBCollectionInvoker {
 	 * @param keys the names of the fields used in this index
 	 * @return
 	 */
-	public static String generateIndexName(Document keys) {
+	public static String generateIndexName(DBObject keys) {
 
 		if (isMongo3Driver()) {
 			return genIndexName(keys);
@@ -79,14 +79,14 @@ class ReflectiveDBCollectionInvoker {
 	}
 
 	/**
-	 * Borrowed from MongoDB Java driver version 2. See
-	 * <a href="http://github.com/mongodb/mongo-java-driver/blob/r2.13.0/src/main/com/mongodb/DBCollection.java#L754" >
-	 * http://github.com/mongodb/mongo-java-driver/blob/r2.13.0/src/main/com/mongodb/DBCollection.java#L754</a>
+	 * Borrowed from MongoDB Java driver version 2. See <a
+	 * href="http://github.com/mongodb/mongo-java-driver/blob/r2.13.0/src/main/com/mongodb/DBCollection.java#L754"
+	 * >http://github.com/mongodb/mongo-java-driver/blob/r2.13.0/src/main/com/mongodb/DBCollection.java#L754</a>
 	 * 
 	 * @param keys
 	 * @return
 	 */
-	private static String genIndexName(Document keys) {
+	private static String genIndexName(DBObject keys) {
 
 		StringBuilder name = new StringBuilder();
 

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/ReflectiveDbInvoker.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2015-2016 the original author or authors.
+ * Copyright 2015 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/ReflectiveWriteResultInvoker.java

@@ -22,7 +22,6 @@ import java.lang.reflect.Method;
 
 import com.mongodb.MongoException;
 import com.mongodb.WriteResult;
-import com.mongodb.client.result.UpdateResult;
 
 /**
  * {@link ReflectiveWriteResultInvoker} provides reflective access to {@link WriteResult} API that is not consistently
@@ -36,7 +35,6 @@ final class ReflectiveWriteResultInvoker {
 
 	private static final Method GET_ERROR_METHOD;
 	private static final Method WAS_ACKNOWLEDGED_METHOD;
-	private static final Method WAS_ACKNOWLEDGED_METHOD_UR;
 
 	private ReflectiveWriteResultInvoker() {}
 
@@ -44,7 +42,6 @@ final class ReflectiveWriteResultInvoker {
 
 		GET_ERROR_METHOD = findMethod(WriteResult.class, "getError");
 		WAS_ACKNOWLEDGED_METHOD = findMethod(WriteResult.class, "wasAcknowledged");
-		WAS_ACKNOWLEDGED_METHOD_UR = findMethod(UpdateResult.class, "wasAcknowledged");
 	}
 
 	/**
@@ -67,12 +64,4 @@ final class ReflectiveWriteResultInvoker {
 	public static boolean wasAcknowledged(WriteResult writeResult) {
 		return isMongo3Driver() ? ((Boolean) invokeMethod(WAS_ACKNOWLEDGED_METHOD, writeResult)).booleanValue() : true;
 	}
-
-	/**
-	 * @param writeResult
-	 * @return return in case of MongoDB Java driver version 2.
-	 */
-	public static boolean wasAcknowledged(UpdateResult writeResult) {
-		return isMongo3Driver() ? ((Boolean) invokeMethod(WAS_ACKNOWLEDGED_METHOD_UR, writeResult)).booleanValue() : true;
-	}
 }

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/SimpleMongoDbFactory.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2011-2016 the original author or authors.
+ * Copyright 2011-2015 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -33,7 +33,6 @@ import com.mongodb.MongoClientURI;
 import com.mongodb.MongoException;
 import com.mongodb.MongoURI;
 import com.mongodb.WriteConcern;
-import com.mongodb.client.MongoDatabase;
 
 /**
  * Factory to create {@link DB} instances from a {@link Mongo} instance.
@@ -188,7 +187,7 @@ public class SimpleMongoDbFactory implements DisposableBean, MongoDbFactory {
 	 * (non-Javadoc)
 	 * @see org.springframework.data.mongodb.MongoDbFactory#getDb()
 	 */
-	public MongoDatabase getDb() throws DataAccessException {
+	public DB getDb() throws DataAccessException {
 		return getDb(databaseName);
 	}
 
@@ -196,17 +195,18 @@ public class SimpleMongoDbFactory implements DisposableBean, MongoDbFactory {
 	 * (non-Javadoc)
 	 * @see org.springframework.data.mongodb.MongoDbFactory#getDb(java.lang.String)
 	 */
-	public MongoDatabase getDb(String dbName) throws DataAccessException {
+	@SuppressWarnings("deprecation")
+	public DB getDb(String dbName) throws DataAccessException {
 
 		Assert.hasText(dbName, "Database name must not be empty.");
 
-		MongoDatabase db = ((MongoClient) mongo).getDatabase(dbName);
+		DB db = MongoDbUtils.getDB(mongo, dbName, credentials, authenticationDatabaseName);
 
-		if (writeConcern == null) {
-			return db;
+		if (writeConcern != null) {
+			db.setWriteConcern(writeConcern);
 		}
 
-		return db.withWriteConcern(writeConcern);
+		return db;
 	}
 
 	/**
@@ -232,10 +232,4 @@ public class SimpleMongoDbFactory implements DisposableBean, MongoDbFactory {
 	public PersistenceExceptionTranslator getExceptionTranslator() {
 		return this.exceptionTranslator;
 	}
-
-	@SuppressWarnings("deprecation")
-	@Override
-	public DB getLegacyDb() {
-		return mongo.getDB(databaseName);
-	}
 }

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/SimpleReactiveMongoDatabaseFactory.java

@@ -1,134 +0,0 @@
-/*
- * Copyright 2016 the original author or authors.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-package org.springframework.data.mongodb.core;
-
-import java.net.UnknownHostException;
-
-import org.springframework.beans.factory.DisposableBean;
-import org.springframework.dao.DataAccessException;
-import org.springframework.dao.support.PersistenceExceptionTranslator;
-import org.springframework.data.mongodb.ReactiveMongoDatabaseFactory;
-import org.springframework.util.Assert;
-
-import com.mongodb.ConnectionString;
-import com.mongodb.WriteConcern;
-import com.mongodb.reactivestreams.client.MongoClient;
-import com.mongodb.reactivestreams.client.MongoClients;
-import com.mongodb.reactivestreams.client.MongoDatabase;
-
-/**
- * Factory to create {@link MongoDatabase} instances from a {@link MongoClient} instance.
- *
- * @author Mark Paluch
- * @since 2.0
- */
-public class SimpleReactiveMongoDatabaseFactory implements DisposableBean, ReactiveMongoDatabaseFactory {
-
-	private final MongoClient mongo;
-	private final String databaseName;
-	private final boolean mongoInstanceCreated;
-	private final PersistenceExceptionTranslator exceptionTranslator;
-
-	private WriteConcern writeConcern;
-
-	/**
-	 * Creates a new {@link SimpleReactiveMongoDatabaseFactory} instance from the given {@link ConnectionString}.
-	 *
-	 * @param connectionString must not be {@literal null}.
-	 * @throws UnknownHostException
-	 */
-	public SimpleReactiveMongoDatabaseFactory(ConnectionString connectionString) throws UnknownHostException {
-		this(MongoClients.create(connectionString), connectionString.getDatabase(), true);
-	}
-
-	/**
-	 * Creates a new {@link SimpleReactiveMongoDatabaseFactory} instance from the given {@link MongoClient}.
-	 *
-	 * @param mongoClient must not be {@literal null}.
-	 * @param databaseName must not be {@literal null}.
-	 * @since 1.7
-	 */
-	public SimpleReactiveMongoDatabaseFactory(MongoClient mongoClient, String databaseName) {
-		this(mongoClient, databaseName, false);
-	}
-
-	private SimpleReactiveMongoDatabaseFactory(MongoClient client, String databaseName, boolean mongoInstanceCreated) {
-
-		Assert.notNull(client, "MongoClient must not be null!");
-		Assert.hasText(databaseName, "Database name must not be empty!");
-		Assert.isTrue(databaseName.matches("[\\w-]+"),
-				"Database name must only contain letters, numbers, underscores and dashes!");
-
-		this.mongo = client;
-		this.databaseName = databaseName;
-		this.mongoInstanceCreated = mongoInstanceCreated;
-		this.exceptionTranslator = new MongoExceptionTranslator();
-	}
-
-	/**
-	 * Configures the {@link WriteConcern} to be used on the {@link MongoDatabase} instance being created.
-	 *
-	 * @param writeConcern the writeConcern to set
-	 */
-	public void setWriteConcern(WriteConcern writeConcern) {
-		this.writeConcern = writeConcern;
-	}
-
-	/*
-	 * (non-Javadoc)
-	 * @see org.springframework.data.mongodb.ReactiveMongoDbFactory#getMongoDatabase()
-	 */
-	public MongoDatabase getMongoDatabase() throws DataAccessException {
-		return getMongoDatabase(databaseName);
-	}
-
-	/*
-	 * (non-Javadoc)
-	 * @see org.springframework.data.mongodb.ReactiveMongoDbFactory#getMongoDatabase(java.lang.String)
-	 */
-	public MongoDatabase getMongoDatabase(String dbName) throws DataAccessException {
-
-		Assert.hasText(dbName, "Database name must not be empty.");
-
-		MongoDatabase db = ReactiveMongoDbUtils.getMongoDatabase(mongo, dbName);
-
-		if (writeConcern != null) {
-
-			db = db.withWriteConcern(writeConcern);
-		}
-
-		return db;
-	}
-
-	/**
-	 * Clean up the Mongo instance if it was created by the factory itself.
-	 *
-	 * @see DisposableBean#destroy()
-	 */
-	public void destroy() throws Exception {
-		if (mongoInstanceCreated) {
-			mongo.close();
-		}
-	}
-
-	/*
-	 * (non-Javadoc)
-	 * @see org.springframework.data.mongodb.ReactiveMongoDbFactory#getExceptionTranslator()
-	 */
-	public PersistenceExceptionTranslator getExceptionTranslator() {
-		return this.exceptionTranslator;
-	}
-}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/AbstractAggregationExpression.java

@@ -0,0 +1,153 @@
+/*
+ * Copyright 2016. the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb.core.aggregation;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.LinkedHashMap;
+import java.util.List;
+
+import org.springframework.util.ObjectUtils;
+
+import com.mongodb.BasicDBObject;
+import com.mongodb.DBObject;
+
+/**
+ * @author Christoph Strobl
+ * @since 1.10
+ */
+abstract class AbstractAggregationExpression implements AggregationExpression {
+
+	private final Object value;
+
+	protected AbstractAggregationExpression(Object value) {
+		this.value = value;
+	}
+
+	/* (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.AggregationExpression#toDbObject(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
+	 */
+	@Override
+	public DBObject toDbObject(AggregationOperationContext context) {
+		return toDbObject(this.value, context);
+	}
+
+	@SuppressWarnings("unchecked")
+	public DBObject toDbObject(Object value, AggregationOperationContext context) {
+
+		Object valueToUse;
+		if (value instanceof List) {
+
+			List<Object> arguments = (List<Object>) value;
+			List<Object> args = new ArrayList<Object>(arguments.size());
+
+			for (Object val : arguments) {
+				args.add(unpack(val, context));
+			}
+			valueToUse = args;
+		} else if (value instanceof java.util.Map) {
+
+			DBObject dbo = new BasicDBObject();
+			for (java.util.Map.Entry<String, Object> entry : ((java.util.Map<String, Object>) value).entrySet()) {
+				dbo.put(entry.getKey(), unpack(entry.getValue(), context));
+			}
+			valueToUse = dbo;
+		} else {
+			valueToUse = unpack(value, context);
+		}
+
+		return new BasicDBObject(getMongoMethod(), valueToUse);
+	}
+
+	protected static List<Field> asFields(String... fieldRefs) {
+
+		if (ObjectUtils.isEmpty(fieldRefs)) {
+			return Collections.emptyList();
+		}
+
+		return Fields.fields(fieldRefs).asList();
+	}
+
+	@SuppressWarnings("unchecked")
+	private Object unpack(Object value, AggregationOperationContext context) {
+
+		if (value instanceof AggregationExpression) {
+			return ((AggregationExpression) value).toDbObject(context);
+		}
+
+		if (value instanceof Field) {
+			return context.getReference((Field) value).toString();
+		}
+
+		if (value instanceof List) {
+
+			List<Object> sourceList = (List<Object>) value;
+			List<Object> mappedList = new ArrayList<Object>(sourceList.size());
+
+			for (Object item : sourceList) {
+				mappedList.add(unpack(item, context));
+			}
+			return mappedList;
+		}
+
+		return value;
+	}
+
+	protected List<Object> append(Object value) {
+
+		if (this.value instanceof List) {
+
+			List<Object> clone = new ArrayList<Object>((List) this.value);
+
+			if (value instanceof List) {
+				for (Object val : (List) value) {
+					clone.add(val);
+				}
+			} else {
+				clone.add(value);
+			}
+			return clone;
+		}
+
+		return Arrays.asList(this.value, value);
+	}
+
+	@SuppressWarnings("unchecked")
+	protected java.util.Map<String, Object> append(String key, Object value) {
+
+		if (!(this.value instanceof java.util.Map)) {
+			throw new IllegalArgumentException("o_O");
+		}
+		java.util.Map<String, Object> clone = new LinkedHashMap<String, Object>((java.util.Map<String, Object>) this.value);
+		clone.put(key, value);
+		return clone;
+
+	}
+
+	protected List<Object> values() {
+
+		if (value instanceof List) {
+			return new ArrayList<Object>((List) value);
+		}
+		if (value instanceof java.util.Map) {
+			return new ArrayList<Object>(((java.util.Map) value).values());
+		}
+		return new ArrayList<Object>(Collections.singletonList(value));
+	}
+
+	protected abstract String getMongoMethod();
+}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/AccumulatorOperators.java

@@ -0,0 +1,648 @@
+/*
+ * Copyright 2016. the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb.core.aggregation;
+
+import java.util.Collections;
+import java.util.List;
+
+import org.springframework.util.Assert;
+
+import com.mongodb.DBObject;
+
+/**
+ * Gateway to {@literal accumulator} aggregation operations.
+ *
+ * @author Christoph Strobl
+ * @since 1.10
+ * @soundtrack Rage Against The Machine - Killing In The Name
+ */
+public class AccumulatorOperators {
+
+	/**
+	 * Take the numeric value referenced by given {@literal fieldReference}.
+	 *
+	 * @param fieldReference must not be {@literal null}.
+	 * @return
+	 */
+	public static AccumulatorOperatorFactory valueOf(String fieldReference) {
+		return new AccumulatorOperatorFactory(fieldReference);
+	}
+
+	/**
+	 * Take the numeric value referenced resulting from given {@link AggregationExpression}.
+	 *
+	 * @param expression must not be {@literal null}.
+	 * @return
+	 */
+	public static AccumulatorOperatorFactory valueOf(AggregationExpression expression) {
+		return new AccumulatorOperatorFactory(expression);
+	}
+
+	/**
+	 * @author Christoph Strobl
+	 */
+	public static class AccumulatorOperatorFactory {
+
+		private final String fieldReference;
+		private final AggregationExpression expression;
+
+		/**
+		 * Creates new {@link AccumulatorOperatorFactory} for given {@literal fieldReference}.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 */
+		public AccumulatorOperatorFactory(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			this.fieldReference = fieldReference;
+			this.expression = null;
+		}
+
+		/**
+		 * Creates new {@link AccumulatorOperatorFactory} for given {@link AggregationExpression}.
+		 *
+		 * @param expression must not be {@literal null}.
+		 */
+		public AccumulatorOperatorFactory(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			this.fieldReference = null;
+			this.expression = expression;
+		}
+
+		/**
+		 * Creates new {@link AggregationExpression} that takes the associated numeric value expression and calculates and
+		 * returns the sum.
+		 *
+		 * @return
+		 */
+		public Sum sum() {
+			return usesFieldRef() ? Sum.sumOf(fieldReference) : Sum.sumOf(expression);
+		}
+
+		/**
+		 * Creates new {@link AggregationExpression} that takes the associated numeric value expression and returns the
+		 * average value.
+		 *
+		 * @return
+		 */
+		public Avg avg() {
+			return usesFieldRef() ? Avg.avgOf(fieldReference) : Avg.avgOf(expression);
+		}
+
+		/**
+		 * Creates new {@link AggregationExpression} that takes the associated numeric value expression and returns the
+		 * maximum value.
+		 *
+		 * @return
+		 */
+		public Max max() {
+			return usesFieldRef() ? Max.maxOf(fieldReference) : Max.maxOf(expression);
+		}
+
+		/**
+		 * Creates new {@link AggregationExpression} that takes the associated numeric value expression and returns the
+		 * minimum value.
+		 *
+		 * @return
+		 */
+		public Min min() {
+			return usesFieldRef() ? Min.minOf(fieldReference) : Min.minOf(expression);
+		}
+
+		/**
+		 * Creates new {@link AggregationExpression} that takes the associated numeric value expression and calculates the
+		 * population standard deviation of the input values.
+		 *
+		 * @return
+		 */
+		public StdDevPop stdDevPop() {
+			return usesFieldRef() ? StdDevPop.stdDevPopOf(fieldReference) : StdDevPop.stdDevPopOf(expression);
+		}
+
+		/**
+		 * Creates new {@link AggregationExpression} that takes the associated numeric value expression and calculates the
+		 * sample standard deviation of the input values.
+		 *
+		 * @return
+		 */
+		public StdDevSamp stdDevSamp() {
+			return usesFieldRef() ? StdDevSamp.stdDevSampOf(fieldReference) : StdDevSamp.stdDevSampOf(expression);
+		}
+
+		private boolean usesFieldRef() {
+			return fieldReference != null;
+		}
+	}
+
+	/**
+	 * {@link AggregationExpression} for {@code $sum}.
+	 *
+	 * @author Christoph Strobl
+	 */
+	public static class Sum extends AbstractAggregationExpression {
+
+		private Sum(Object value) {
+			super(value);
+		}
+
+		@Override
+		protected String getMongoMethod() {
+			return "$sum";
+		}
+
+		/**
+		 * Creates new {@link Sum}.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public static Sum sumOf(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			return new Sum(asFields(fieldReference));
+		}
+
+		/**
+		 * Creates new {@link Sum}.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public static Sum sumOf(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return new Sum(Collections.singletonList(expression));
+		}
+
+		/**
+		 * Creates new {@link Sum} with all previously added arguments appending the given one. <br />
+		 * <strong>NOTE:</strong> Only possible in {@code $project} stage.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public Sum and(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			return new Sum(append(Fields.field(fieldReference)));
+		}
+
+		/**
+		 * Creates new {@link Sum} with all previously added arguments appending the given one. <br />
+		 * <strong>NOTE:</strong> Only possible in {@code $project} stage.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public Sum and(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return new Sum(append(expression));
+		}
+
+		/* (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.AccumulatorOperators.AbstractAggregationExpression#toDbObject(java.lang.Object, org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
+		 */
+		@Override
+		@SuppressWarnings("unchecked")
+		public DBObject toDbObject(Object value, AggregationOperationContext context) {
+
+			if (value instanceof List) {
+				if (((List) value).size() == 1) {
+					return super.toDbObject(((List<Object>) value).iterator().next(), context);
+				}
+			}
+
+			return super.toDbObject(value, context);
+		}
+	}
+
+	/**
+	 * {@link AggregationExpression} for {@code $avg}.
+	 *
+	 * @author Christoph Strobl
+	 */
+	public static class Avg extends AbstractAggregationExpression {
+
+		private Avg(Object value) {
+			super(value);
+		}
+
+		@Override
+		protected String getMongoMethod() {
+			return "$avg";
+		}
+
+		/**
+		 * Creates new {@link Avg}.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public static Avg avgOf(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			return new Avg(asFields(fieldReference));
+		}
+
+		/**
+		 * Creates new {@link Avg}.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public static Avg avgOf(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return new Avg(Collections.singletonList(expression));
+		}
+
+		/**
+		 * Creates new {@link Avg} with all previously added arguments appending the given one. <br />
+		 * <strong>NOTE:</strong> Only possible in {@code $project} stage.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public Avg and(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			return new Avg(append(Fields.field(fieldReference)));
+		}
+
+		/**
+		 * Creates new {@link Avg} with all previously added arguments appending the given one. <br />
+		 * <strong>NOTE:</strong> Only possible in {@code $project} stage.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public Avg and(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return new Avg(append(expression));
+		}
+
+		/* (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.AccumulatorOperators.AbstractAggregationExpression#toDbObject(java.lang.Object, org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
+		 */
+		@Override
+		@SuppressWarnings("unchecked")
+		public DBObject toDbObject(Object value, AggregationOperationContext context) {
+
+			if (value instanceof List) {
+				if (((List) value).size() == 1) {
+					return super.toDbObject(((List<Object>) value).iterator().next(), context);
+				}
+			}
+
+			return super.toDbObject(value, context);
+		}
+	}
+
+	/**
+	 * {@link AggregationExpression} for {@code $max}.
+	 *
+	 * @author Christoph Strobl
+	 */
+	public static class Max extends AbstractAggregationExpression {
+
+		private Max(Object value) {
+			super(value);
+		}
+
+		@Override
+		protected String getMongoMethod() {
+			return "$max";
+		}
+
+		/**
+		 * Creates new {@link Max}.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public static Max maxOf(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			return new Max(asFields(fieldReference));
+		}
+
+		/**
+		 * Creates new {@link Max}.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public static Max maxOf(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return new Max(Collections.singletonList(expression));
+		}
+
+		/**
+		 * Creates new {@link Max} with all previously added arguments appending the given one. <br />
+		 * <strong>NOTE:</strong> Only possible in {@code $project} stage.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public Max and(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			return new Max(append(Fields.field(fieldReference)));
+		}
+
+		/**
+		 * Creates new {@link Max} with all previously added arguments appending the given one. <br />
+		 * <strong>NOTE:</strong> Only possible in {@code $project} stage.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public Max and(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return new Max(append(expression));
+		}
+
+		/* (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.AccumulatorOperators.AbstractAggregationExpression#toDbObject(java.lang.Object, org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
+		 */
+		@Override
+		@SuppressWarnings("unchecked")
+		public DBObject toDbObject(Object value, AggregationOperationContext context) {
+
+			if (value instanceof List) {
+				if (((List) value).size() == 1) {
+					return super.toDbObject(((List<Object>) value).iterator().next(), context);
+				}
+			}
+
+			return super.toDbObject(value, context);
+		}
+	}
+
+	/**
+	 * {@link AggregationExpression} for {@code $min}.
+	 *
+	 * @author Christoph Strobl
+	 */
+	public static class Min extends AbstractAggregationExpression {
+
+		private Min(Object value) {
+			super(value);
+		}
+
+		@Override
+		protected String getMongoMethod() {
+			return "$min";
+		}
+
+		/**
+		 * Creates new {@link Min}.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public static Min minOf(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			return new Min(asFields(fieldReference));
+		}
+
+		/**
+		 * Creates new {@link Min}.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public static Min minOf(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return new Min(Collections.singletonList(expression));
+		}
+
+		/**
+		 * Creates new {@link Min} with all previously added arguments appending the given one. <br />
+		 * <strong>NOTE:</strong> Only possible in {@code $project} stage.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public Min and(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			return new Min(append(Fields.field(fieldReference)));
+		}
+
+		/**
+		 * Creates new {@link Min} with all previously added arguments appending the given one. <br />
+		 * <strong>NOTE:</strong> Only possible in {@code $project} stage.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public Min and(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return new Min(append(expression));
+		}
+
+		/* (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.AccumulatorOperators.AbstractAggregationExpression#toDbObject(java.lang.Object, org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
+		 */
+		@Override
+		@SuppressWarnings("unchecked")
+		public DBObject toDbObject(Object value, AggregationOperationContext context) {
+
+			if (value instanceof List) {
+				if (((List) value).size() == 1) {
+					return super.toDbObject(((List<Object>) value).iterator().next(), context);
+				}
+			}
+
+			return super.toDbObject(value, context);
+		}
+	}
+
+	/**
+	 * {@link AggregationExpression} for {@code $stdDevPop}.
+	 *
+	 * @author Christoph Strobl
+	 */
+	public static class StdDevPop extends AbstractAggregationExpression {
+
+		private StdDevPop(Object value) {
+			super(value);
+		}
+
+		@Override
+		protected String getMongoMethod() {
+			return "$stdDevPop";
+		}
+
+		/**
+		 * Creates new {@link StdDevPop}.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public static StdDevPop stdDevPopOf(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			return new StdDevPop(asFields(fieldReference));
+		}
+
+		/**
+		 * Creates new {@link StdDevPop} with all previously added arguments appending the given one.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public static StdDevPop stdDevPopOf(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return new StdDevPop(Collections.singletonList(expression));
+		}
+
+		/**
+		 * Creates new {@link StdDevPop} with all previously added arguments appending the given one. <br/>
+		 * <strong>NOTE:</strong> Only possible in {@code $project} stage.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public StdDevPop and(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			return new StdDevPop(append(Fields.field(fieldReference)));
+		}
+
+		/**
+		 * Creates new {@link StdDevSamp} with all previously added arguments appending the given one. <br />
+		 * <strong>NOTE:</strong> Only possible in {@code $project} stage.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public StdDevPop and(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return new StdDevPop(append(expression));
+		}
+
+		/* (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.AccumulatorOperators.AbstractAggregationExpression#toDbObject(java.lang.Object, org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
+		 */
+		@Override
+		@SuppressWarnings("unchecked")
+		public DBObject toDbObject(Object value, AggregationOperationContext context) {
+
+			if (value instanceof List) {
+				if (((List) value).size() == 1) {
+					return super.toDbObject(((List<Object>) value).iterator().next(), context);
+				}
+			}
+
+			return super.toDbObject(value, context);
+		}
+	}
+
+	/**
+	 * {@link AggregationExpression} for {@code $stdDevSamp}.
+	 *
+	 * @author Christoph Strobl
+	 */
+	public static class StdDevSamp extends AbstractAggregationExpression {
+
+		private StdDevSamp(Object value) {
+			super(value);
+		}
+
+		@Override
+		protected String getMongoMethod() {
+			return "$stdDevSamp";
+		}
+
+		/**
+		 * Creates new {@link StdDevSamp}.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public static StdDevSamp stdDevSampOf(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			return new StdDevSamp(asFields(fieldReference));
+		}
+
+		/**
+		 * Creates new {@link StdDevSamp}.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public static StdDevSamp stdDevSampOf(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return new StdDevSamp(Collections.singletonList(expression));
+		}
+
+		/**
+		 * Creates new {@link StdDevSamp} with all previously added arguments appending the given one. <br />
+		 * <strong>NOTE:</strong> Only possible in {@code $project} stage.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public StdDevSamp and(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			return new StdDevSamp(append(Fields.field(fieldReference)));
+		}
+
+		/**
+		 * Creates new {@link StdDevSamp} with all previously added arguments appending the given one. <br />
+		 * <strong>NOTE:</strong> Only possible in {@code $project} stage.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public StdDevSamp and(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return new StdDevSamp(append(expression));
+		}
+
+		/* (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.AccumulatorOperators.AbstractAggregationExpression#toDbObject(java.lang.Object, org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
+		 */
+		@Override
+		@SuppressWarnings("unchecked")
+		public DBObject toDbObject(Object value, AggregationOperationContext context) {
+
+			if (value instanceof List) {
+				if (((List) value).size() == 1) {
+					return super.toDbObject(((List<Object>) value).iterator().next(), context);
+				}
+			}
+
+			return super.toDbObject(value, context);
+		}
+	}
+}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/Aggregation.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2016 the original author or authors.
+ * Copyright 2013-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,18 +21,27 @@ import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
 
-import org.bson.Document;
 import org.springframework.data.domain.Sort;
 import org.springframework.data.domain.Sort.Direction;
+import org.springframework.data.mongodb.core.aggregation.CountOperation.CountOperationBuilder;
+import org.springframework.data.mongodb.core.aggregation.ExposedFields.DirectFieldReference;
 import org.springframework.data.mongodb.core.aggregation.ExposedFields.ExposedField;
 import org.springframework.data.mongodb.core.aggregation.ExposedFields.FieldReference;
-import org.springframework.data.mongodb.core.aggregation.Fields.AggregationField;
+import org.springframework.data.mongodb.core.aggregation.FacetOperation.FacetOperationBuilder;
 import org.springframework.data.mongodb.core.aggregation.FieldsExposingAggregationOperation.InheritsFieldsAggregationOperation;
+import org.springframework.data.mongodb.core.aggregation.GraphLookupOperation.StartWithBuilder;
+import org.springframework.data.mongodb.core.aggregation.ReplaceRootOperation.ReplaceRootDocumentOperationBuilder;
+import org.springframework.data.mongodb.core.aggregation.ReplaceRootOperation.ReplaceRootOperationBuilder;
+import org.springframework.data.mongodb.core.aggregation.Fields.*;
 import org.springframework.data.mongodb.core.query.Criteria;
+import org.springframework.data.mongodb.core.query.CriteriaDefinition;
 import org.springframework.data.mongodb.core.query.NearQuery;
 import org.springframework.data.mongodb.core.query.SerializationUtils;
 import org.springframework.util.Assert;
 
+import com.mongodb.BasicDBObject;
+import com.mongodb.DBObject;
+
 /**
  * An {@code Aggregation} is a representation of a list of aggregation steps to be performed by the MongoDB Aggregation
  * Framework.
@@ -60,7 +69,7 @@ public class Aggregation {
 	 */
 	public static final String CURRENT = SystemVariable.CURRENT.toString();
 
-	public static final AggregationOperationContext DEFAULT_CONTEXT = new NoOpAggregationOperationContext();
+	public static final AggregationOperationContext DEFAULT_CONTEXT = AggregationOperationRenderer.DEFAULT_CONTEXT;
 	public static final AggregationOptions DEFAULT_OPTIONS = newAggregationOptions().build();
 
 	protected final List<AggregationOperation> operations;
@@ -194,7 +203,7 @@ public class Aggregation {
 	}
 
 	/**
-	 * Creates a new {@link ProjectionOperation} includeing the given {@link Fields}.
+	 * Creates a new {@link ProjectionOperation} including the given {@link Fields}.
 	 *
 	 * @param fields must not be {@literal null}.
 	 * @return
@@ -213,6 +222,40 @@ public class Aggregation {
 		return new UnwindOperation(field(field));
 	}
 
+	/**
+	 * Factory method to create a new {@link ReplaceRootOperation} for the field with the given name.
+	 *
+	 * @param fieldName must not be {@literal null} or empty.
+	 * @return
+	 * @since 1.10
+	 */
+	public static ReplaceRootOperation replaceRoot(String fieldName) {
+		return ReplaceRootOperation.builder().withValueOf(fieldName);
+	}
+
+	/**
+	 * Factory method to create a new {@link ReplaceRootOperation} for the field with the given
+	 * {@link AggregationExpression}.
+	 *
+	 * @param aggregationExpression must not be {@literal null}.
+	 * @return
+	 * @since 1.10
+	 */
+	public static ReplaceRootOperation replaceRoot(AggregationExpression aggregationExpression) {
+		return ReplaceRootOperation.builder().withValueOf(aggregationExpression);
+	}
+
+	/**
+	 * Factory method to create a new {@link ReplaceRootDocumentOperationBuilder} to configure a
+	 * {@link ReplaceRootOperation}.
+	 *
+	 * @return the {@literal ReplaceRootDocumentOperationBuilder}.
+	 * @since 1.10
+	 */
+	public static ReplaceRootOperationBuilder replaceRoot() {
+		return ReplaceRootOperation.builder();
+	}
+
 	/**
 	 * Factory method to create a new {@link UnwindOperation} for the field with the given name and
 	 * {@code preserveNullAndEmptyArrays}. Note that extended unwind is supported in MongoDB version 3.2+.
@@ -277,6 +320,18 @@ public class Aggregation {
 		return new GroupOperation(fields);
 	}
 
+	/**
+	 * Creates a new {@link GraphLookupOperation.GraphLookupOperationFromBuilder} to construct a
+	 * {@link GraphLookupOperation} given {@literal fromCollection}.
+	 *
+	 * @param fromCollection must not be {@literal null} or empty.
+	 * @return
+	 * @since 1.10
+	 */
+	public static StartWithBuilder graphLookup(String fromCollection) {
+		return GraphLookupOperation.builder().from(fromCollection);
+	}
+
 	/**
 	 * Factory method to create a new {@link SortOperation} for the given {@link Sort}.
 	 *
@@ -339,6 +394,17 @@ public class Aggregation {
 		return new MatchOperation(criteria);
 	}
 
+	/**
+	 * Creates a new {@link MatchOperation} using the given {@link CriteriaDefinition}.
+	 *
+	 * @param criteria must not be {@literal null}.
+	 * @return
+	 * @since 1.10
+	 */
+	public static MatchOperation match(CriteriaDefinition criteria) {
+		return new MatchOperation(criteria);
+	}
+
 	/**
 	 * Creates a new {@link OutOperation} using the given collection name. This operation must be the last operation in
 	 * the pipeline.
@@ -353,6 +419,73 @@ public class Aggregation {
 		return new OutOperation(outCollectionName);
 	}
 
+	/**
+	 * Creates a new {@link BucketOperation} given {@literal groupByField}.
+	 *
+	 * @param groupByField must not be {@literal null} or empty.
+	 * @return
+	 * @since 1.10
+	 */
+	public static BucketOperation bucket(String groupByField) {
+		return new BucketOperation(field(groupByField));
+	}
+
+	/**
+	 * Creates a new {@link BucketOperation} given {@link AggregationExpression group-by expression}.
+	 *
+	 * @param groupByExpression must not be {@literal null}.
+	 * @return
+	 * @since 1.10
+	 */
+	public static BucketOperation bucket(AggregationExpression groupByExpression) {
+		return new BucketOperation(groupByExpression);
+	}
+
+	/**
+	 * Creates a new {@link BucketAutoOperation} given {@literal groupByField}.
+	 *
+	 * @param groupByField must not be {@literal null} or empty.
+	 * @param buckets number of buckets, must be a positive integer.
+	 * @return
+	 * @since 1.10
+	 */
+	public static BucketAutoOperation bucketAuto(String groupByField, int buckets) {
+		return new BucketAutoOperation(field(groupByField), buckets);
+	}
+
+	/**
+	 * Creates a new {@link BucketAutoOperation} given {@link AggregationExpression group-by expression}.
+	 *
+	 * @param groupByExpression must not be {@literal null}.
+	 * @param buckets number of buckets, must be a positive integer.
+	 * @return
+	 * @since 1.10
+	 */
+	public static BucketAutoOperation bucketAuto(AggregationExpression groupByExpression, int buckets) {
+		return new BucketAutoOperation(groupByExpression, buckets);
+	}
+
+	/**
+	 * Creates a new {@link FacetOperation}.
+	 *
+	 * @return
+	 * @since 1.10
+	 */
+	public static FacetOperation facet() {
+		return FacetOperation.EMPTY;
+	}
+
+	/**
+	 * Creates a new {@link FacetOperationBuilder} given {@link Aggregation}.
+	 *
+	 * @param aggregationOperations the sub-pipeline, must not be {@literal null}.
+	 * @return
+	 * @since 1.10
+	 */
+	public static FacetOperationBuilder facet(AggregationOperation... aggregationOperations) {
+		return facet().and(aggregationOperations);
+	}
+
 	/**
 	 * Creates a new {@link LookupOperation}.
 	 *
@@ -382,65 +515,13 @@ public class Aggregation {
 	}
 
 	/**
-	 * Creates a new {@link IfNullOperator} for the given {@code field} and {@code replacement} value.
+	 * Creates a new {@link CountOperationBuilder}.
 	 *
-	 * @param field must not be {@literal null}.
-	 * @param replacement must not be {@literal null}.
 	 * @return never {@literal null}.
 	 * @since 1.10
 	 */
-	public static IfNullOperator ifNull(String field, Object replacement) {
-		return IfNullOperator.newBuilder().ifNull(field).thenReplaceWith(replacement);
-	}
-
-	/**
-	 * Creates a new {@link IfNullOperator} for the given {@link Field} and {@link Field} to obtain a value from.
-	 *
-	 * @param field must not be {@literal null}.
-	 * @param replacement must not be {@literal null}.
-	 * @return never {@literal null}.
-	 * @since 1.10
-	 */
-	public static IfNullOperator ifNull(Field field, Field replacement) {
-		return IfNullOperator.newBuilder().ifNull(field).thenReplaceWith(replacement);
-	}
-
-	/**
-	 * Creates a new {@link IfNullOperator} for the given {@link Field} and {@code replacement} value.
-	 *
-	 * @param field must not be {@literal null}.
-	 * @param replacement must not be {@literal null}.
-	 * @return never {@literal null}.
-	 * @since 1.10
-	 */
-	public static IfNullOperator ifNull(Field field, Object replacement) {
-		return IfNullOperator.newBuilder().ifNull(field).thenReplaceWith(replacement);
-	}
-
-	/**
-	 * Creates a new {@link ConditionalOperator} for the given {@link Field} that holds a {@literal boolean} value.
-	 *
-	 * @param booleanField must not be {@literal null}.
-	 * @param then must not be {@literal null}.
-	 * @param otherwise must not be {@literal null}.
-	 * @return never {@literal null}.
-	 * @since 1.10
-	 */
-	public static ConditionalOperator conditional(Field booleanField, Object then, Object otherwise) {
-		return ConditionalOperator.newBuilder().when(booleanField).then(then).otherwise(otherwise);
-	}
-
-	/**
-	 * Creates a new {@link ConditionalOperator} for the given {@link Criteria}.
-	 *
-	 * @param criteria must not be {@literal null}.
-	 * @param then must not be {@literal null}.
-	 * @param otherwise must not be {@literal null}.
-	 * @return never {@literal null}.
-	 * @since 1.10
-	 */
-	public static ConditionalOperator conditional(Criteria criteria, Object then, Object otherwise) {
-		return ConditionalOperator.newBuilder().when(criteria).then(then).otherwise(otherwise);
+	public static CountOperationBuilder count() {
+		return new CountOperationBuilder();
 	}
 
 	/**
@@ -489,33 +570,16 @@ public class Aggregation {
 	}
 
 	/**
-	 * Converts this {@link Aggregation} specification to a {@link Document}.
+	 * Converts this {@link Aggregation} specification to a {@link DBObject}.
 	 *
 	 * @param inputCollectionName the name of the input collection
-	 * @return the {@code Document} representing this aggregation
+	 * @return the {@code DBObject} representing this aggregation
 	 */
-	public Document toDocument(String inputCollectionName, AggregationOperationContext rootContext) {
+	public DBObject toDbObject(String inputCollectionName, AggregationOperationContext rootContext) {
 
-		AggregationOperationContext context = rootContext;
-		List<Document> operationDocuments = new ArrayList<Document>(operations.size());
+		List<DBObject> operationDocuments = AggregationOperationRenderer.toDBObject(operations, rootContext);
 
-		for (AggregationOperation operation : operations) {
-
-			operationDocuments.add(operation.toDocument(context));
-
-			if (operation instanceof FieldsExposingAggregationOperation) {
-
-				FieldsExposingAggregationOperation exposedFieldsOperation = (FieldsExposingAggregationOperation) operation;
-
-				if (operation instanceof InheritsFieldsAggregationOperation) {
-					context = new InheritingExposedFieldsAggregationOperationContext(exposedFieldsOperation.getFields(), context);
-				} else {
-					context = new ExposedFieldsAggregationOperationContext(exposedFieldsOperation.getFields(), context);
-				}
-			}
-		}
-
-		Document command = new Document("aggregate", inputCollectionName);
+		DBObject command = new BasicDBObject("aggregate", inputCollectionName);
 		command.put("pipeline", operationDocuments);
 
 		command = options.applyAndReturnPotentiallyChangedCommand(command);
@@ -529,50 +593,14 @@ public class Aggregation {
 	 */
 	@Override
 	public String toString() {
-		return SerializationUtils
-				.serializeToJsonSafely(toDocument("__collection__", new NoOpAggregationOperationContext()));
-	}
-
-	/**
-	 * Simple {@link AggregationOperationContext} that just returns {@link FieldReference}s as is.
-	 *
-	 * @author Oliver Gierke
-	 */
-	private static class NoOpAggregationOperationContext implements AggregationOperationContext {
-
-		/* 
-		 * (non-Javadoc)
-		 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperationContext#getMappedObject(com.mongodb.Document)
-		 */
-		@Override
-		public Document getMappedObject(Document document) {
-			return document;
-		}
-
-		/* 
-		 * (non-Javadoc)
-		 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperationContext#getReference(org.springframework.data.mongodb.core.aggregation.ExposedFields.AvailableField)
-		 */
-		@Override
-		public FieldReference getReference(Field field) {
-			return new FieldReference(new ExposedField(field, true));
-		}
-
-		/* 
-		 * (non-Javadoc)
-		 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperationContext#getReference(java.lang.String)
-		 */
-		@Override
-		public FieldReference getReference(String name) {
-			return new FieldReference(new ExposedField(new AggregationField(name), true));
-		}
+		return SerializationUtils.serializeToJsonSafely(toDbObject("__collection__", DEFAULT_CONTEXT));
 	}
 
 	/**
 	 * Describes the system variables available in MongoDB aggregation framework pipeline expressions.
 	 *
 	 * @author Thomas Darimont
-	 * @see http://docs.mongodb.org/manual/reference/aggregation-variables
+	 * @see <a href="https://docs.mongodb.org/manual/reference/aggregation-variables">Aggregation Variables</a>
 	 */
 	enum SystemVariable {
 
@@ -605,7 +633,7 @@ public class Aggregation {
 			return false;
 		}
 
-		/* 
+		/*
 		 * (non-Javadoc)
 		 * @see java.lang.Enum#toString()
 		 */

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/AggregationExpression.java

@@ -15,7 +15,7 @@
  */
 package org.springframework.data.mongodb.core.aggregation;
 
-import org.bson.Document;
+import com.mongodb.DBObject;
 
 /**
  * An {@link AggregationExpression} can be used with field expressions in aggregation pipeline stages like
@@ -28,11 +28,11 @@ import org.bson.Document;
 public interface AggregationExpression {
 
 	/**
-	 * Turns the {@link AggregationExpression} into a {@link Document} within the given
+	 * Turns the {@link AggregationExpression} into a {@link DBObject} within the given
 	 * {@link AggregationOperationContext}.
 	 *
 	 * @param context
 	 * @return
 	 */
-	Document toDocument(AggregationOperationContext context);
+	DBObject toDbObject(AggregationOperationContext context);
 }

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/AggregationExpressionTransformer.java

@@ -15,7 +15,6 @@
  */
 package org.springframework.data.mongodb.core.aggregation;
 
-import org.bson.Document;
 import org.springframework.data.mongodb.core.aggregation.AggregationExpressionTransformer.AggregationExpressionTransformationContext;
 import org.springframework.data.mongodb.core.aggregation.ExposedFields.FieldReference;
 import org.springframework.data.mongodb.core.spel.ExpressionNode;
@@ -23,16 +22,16 @@ import org.springframework.data.mongodb.core.spel.ExpressionTransformationContex
 import org.springframework.data.mongodb.core.spel.ExpressionTransformer;
 import org.springframework.util.Assert;
 
+import com.mongodb.DBObject;
+
 /**
  * Interface to type an {@link ExpressionTransformer} to the contained
  * {@link AggregationExpressionTransformationContext}.
  * 
  * @author Oliver Gierke
- * @author Christoph Strobl
- * @since 1.4
  */
-interface AggregationExpressionTransformer
-		extends ExpressionTransformer<AggregationExpressionTransformationContext<ExpressionNode>> {
+interface AggregationExpressionTransformer extends
+		ExpressionTransformer<AggregationExpressionTransformationContext<ExpressionNode>> {
 
 	/**
 	 * A special {@link ExpressionTransformationContextSupport} to be aware of the {@link AggregationOperationContext}.
@@ -40,8 +39,8 @@ interface AggregationExpressionTransformer
 	 * @author Oliver Gierke
 	 * @author Thomas Darimont
 	 */
-	class AggregationExpressionTransformationContext<T extends ExpressionNode>
-			extends ExpressionTransformationContextSupport<T> {
+	public static class AggregationExpressionTransformationContext<T extends ExpressionNode> extends
+			ExpressionTransformationContextSupport<T> {
 
 		private final AggregationOperationContext aggregationContext;
 
@@ -54,7 +53,7 @@ interface AggregationExpressionTransformer
 		 * @param aggregationContext must not be {@literal null}.
 		 */
 		public AggregationExpressionTransformationContext(T currentNode, ExpressionNode parentNode,
-				Document previousOperationObject, AggregationOperationContext context) {
+				DBObject previousOperationObject, AggregationOperationContext context) {
 
 			super(currentNode, parentNode, previousOperationObject);
 

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/AggregationFunctionExpressions.java

@@ -19,21 +19,24 @@ import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
 
-import org.bson.Document;
 import org.springframework.util.Assert;
 
+import com.mongodb.BasicDBObject;
+import com.mongodb.DBObject;
+
 /**
  * An enum of supported {@link AggregationExpression}s in aggregation pipeline stages.
  * 
  * @author Thomas Darimont
  * @author Oliver Gierke
  * @author Christoph Strobl
- * @author Mark Paluch
  * @since 1.7
+ * @deprecated since 1.10. Please use {@link ArithmeticOperators} and {@link ComparisonOperators} instead.
  */
+@Deprecated
 public enum AggregationFunctionExpressions {
 
-	SIZE;
+	SIZE, CMP, EQ, GT, GTE, LT, LTE, NE, SUBTRACT, ADD, MULTIPLY;
 
 	/**
 	 * Returns an {@link AggregationExpression} build from the current {@link Enum} name and the given parameters.
@@ -52,7 +55,7 @@ public enum AggregationFunctionExpressions {
 	 * 
 	 * @author Thomas Darimont
 	 * @author Oliver Gierke
-	 * @since 1.10
+	 * @since 1.7
 	 */
 	static class FunctionExpression implements AggregationExpression {
 
@@ -76,10 +79,10 @@ public enum AggregationFunctionExpressions {
 
 		/*
 		 * (non-Javadoc)
-		 * @see org.springframework.data.mongodb.core.aggregation.Expression#toDocument(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
+		 * @see org.springframework.data.mongodb.core.aggregation.Expression#toDbObject(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
 		 */
 		@Override
-		public Document toDocument(AggregationOperationContext context) {
+		public DBObject toDbObject(AggregationOperationContext context) {
 
 			List<Object> args = new ArrayList<Object>(values.size());
 
@@ -87,13 +90,13 @@ public enum AggregationFunctionExpressions {
 				args.add(unpack(value, context));
 			}
 
-			return new Document("$" + name, args);
+			return new BasicDBObject("$" + name, args);
 		}
 
 		private static Object unpack(Object value, AggregationOperationContext context) {
 
 			if (value instanceof AggregationExpression) {
-				return ((AggregationExpression) value).toDocument(context);
+				return ((AggregationExpression) value).toDbObject(context);
 			}
 
 			if (value instanceof Field) {

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/AggregationOperation.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2016 the original author or authors.
+ * Copyright 2013 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -15,7 +15,7 @@
  */
 package org.springframework.data.mongodb.core.aggregation;
 
-import org.bson.Document;
+import com.mongodb.DBObject;
 
 /**
  * Represents one single operation in an aggregation pipeline.
@@ -23,16 +23,15 @@ import org.bson.Document;
  * @author Sebastian Herold
  * @author Thomas Darimont
  * @author Oliver Gierke
- * @author Christoph Strobl
  * @since 1.3
  */
 public interface AggregationOperation {
 
 	/**
-	 * Turns the {@link AggregationOperation} into a {@link Document} by using the given
+	 * Turns the {@link AggregationOperation} into a {@link DBObject} by using the given
 	 * {@link AggregationOperationContext}.
 	 * 
-	 * @return the Document
+	 * @return the DBObject
 	 */
-	Document toDocument(AggregationOperationContext context);
+	DBObject toDBObject(AggregationOperationContext context);
 }

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/AggregationOperationContext.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2016 the original author or authors.
+ * Copyright 2013 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -15,25 +15,25 @@
  */
 package org.springframework.data.mongodb.core.aggregation;
 
-import org.bson.Document;
 import org.springframework.data.mongodb.core.aggregation.ExposedFields.FieldReference;
 
+import com.mongodb.DBObject;
+
 /**
  * The context for an {@link AggregationOperation}.
  * 
  * @author Oliver Gierke
- * @author Christoph Strobl
  * @since 1.3
  */
 public interface AggregationOperationContext {
 
 	/**
-	 * Returns the mapped {@link Document}, potentially converting the source considering mapping metadata etc.
+	 * Returns the mapped {@link DBObject}, potentially converting the source considering mapping metadata etc.
 	 * 
-	 * @param document will never be {@literal null}.
+	 * @param dbObject will never be {@literal null}.
 	 * @return must not be {@literal null}.
 	 */
-	Document getMappedObject(Document document);
+	DBObject getMappedObject(DBObject dbObject);
 
 	/**
 	 * Returns a {@link FieldReference} for the given field or {@literal null} if the context does not expose the given

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/AggregationOperationRenderer.java

@@ -0,0 +1,109 @@
+/*
+ * Copyright 2016 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb.core.aggregation;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.springframework.data.mongodb.core.aggregation.ExposedFields.DirectFieldReference;
+import org.springframework.data.mongodb.core.aggregation.ExposedFields.ExposedField;
+import org.springframework.data.mongodb.core.aggregation.ExposedFields.FieldReference;
+import org.springframework.data.mongodb.core.aggregation.Fields.AggregationField;
+import org.springframework.data.mongodb.core.aggregation.FieldsExposingAggregationOperation.InheritsFieldsAggregationOperation;
+
+import com.mongodb.DBObject;
+
+/**
+ * Rendering support for {@link AggregationOperation} into a {@link List} of {@link com.mongodb.DBObject}.
+ *
+ * @author Mark Paluch
+ * @author Christoph Strobl
+ * @since 1.10
+ */
+class AggregationOperationRenderer {
+
+	static final AggregationOperationContext DEFAULT_CONTEXT = new NoOpAggregationOperationContext();
+
+	/**
+	 * Render a {@link List} of {@link AggregationOperation} given {@link AggregationOperationContext} into their
+	 * {@link DBObject} representation.
+	 *
+	 * @param operations must not be {@literal null}.
+	 * @param context must not be {@literal null}.
+	 * @return the {@link List} of {@link DBObject}.
+	 */
+	static List<DBObject> toDBObject(List<AggregationOperation> operations, AggregationOperationContext rootContext) {
+
+		List<DBObject> operationDocuments = new ArrayList<DBObject>(operations.size());
+
+		AggregationOperationContext contextToUse = rootContext;
+
+		for (AggregationOperation operation : operations) {
+
+			operationDocuments.add(operation.toDBObject(contextToUse));
+
+			if (operation instanceof FieldsExposingAggregationOperation) {
+
+				FieldsExposingAggregationOperation exposedFieldsOperation = (FieldsExposingAggregationOperation) operation;
+				ExposedFields fields = exposedFieldsOperation.getFields();
+
+				if (operation instanceof InheritsFieldsAggregationOperation) {
+					contextToUse = new InheritingExposedFieldsAggregationOperationContext(fields, contextToUse);
+				} else {
+					contextToUse = fields.exposesNoFields() ? DEFAULT_CONTEXT
+							: new ExposedFieldsAggregationOperationContext(exposedFieldsOperation.getFields(), contextToUse);
+				}
+			}
+		}
+
+		return operationDocuments;
+	}
+
+	/**
+	 * Simple {@link AggregationOperationContext} that just returns {@link FieldReference}s as is.
+	 *
+	 * @author Oliver Gierke
+	 */
+	private static class NoOpAggregationOperationContext implements AggregationOperationContext {
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperationContext#getMappedObject(com.mongodb.DBObject)
+		 */
+		@Override
+		public DBObject getMappedObject(DBObject dbObject) {
+			return dbObject;
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperationContext#getReference(org.springframework.data.mongodb.core.aggregation.ExposedFields.AvailableField)
+		 */
+		@Override
+		public FieldReference getReference(Field field) {
+			return new DirectFieldReference(new ExposedField(field, true));
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperationContext#getReference(java.lang.String)
+		 */
+		@Override
+		public FieldReference getReference(String name) {
+			return new DirectFieldReference(new ExposedField(new AggregationField(name), true));
+		}
+	}
+}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/AggregationOptions.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2016 the original author or authors.
+ * Copyright 2014 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -15,16 +15,16 @@
  */
 package org.springframework.data.mongodb.core.aggregation;
 
-import org.bson.Document;
+import com.mongodb.BasicDBObject;
+import com.mongodb.DBObject;
 
 /**
  * Holds a set of configurable aggregation options that can be used within an aggregation pipeline. A list of support
  * aggregation options can be found in the MongoDB reference documentation
- * http://docs.mongodb.org/manual/reference/command/aggregate/#aggregate
+ * https://docs.mongodb.org/manual/reference/command/aggregate/#aggregate
  * 
  * @author Thomas Darimont
  * @author Oliver Gierke
- * @author Christoph Strobl
  * @see Aggregation#withOptions(AggregationOptions)
  * @see TypedAggregation#withOptions(AggregationOptions)
  * @since 1.6
@@ -37,7 +37,7 @@ public class AggregationOptions {
 
 	private final boolean allowDiskUse;
 	private final boolean explain;
-	private final Document cursor;
+	private final DBObject cursor;
 
 	/**
 	 * Creates a new {@link AggregationOptions}.
@@ -46,7 +46,7 @@ public class AggregationOptions {
 	 * @param explain whether to get the execution plan for the aggregation instead of the actual results.
 	 * @param cursor can be {@literal null}, used to pass additional options to the aggregation.
 	 */
-	public AggregationOptions(boolean allowDiskUse, boolean explain, Document cursor) {
+	public AggregationOptions(boolean allowDiskUse, boolean explain, DBObject cursor) {
 
 		this.allowDiskUse = allowDiskUse;
 		this.explain = explain;
@@ -77,7 +77,7 @@ public class AggregationOptions {
 	 * 
 	 * @return
 	 */
-	public Document getCursor() {
+	public DBObject getCursor() {
 		return cursor;
 	}
 
@@ -88,19 +88,19 @@ public class AggregationOptions {
 	 * @param command the aggregation command.
 	 * @return
 	 */
-	Document applyAndReturnPotentiallyChangedCommand(Document command) {
+	DBObject applyAndReturnPotentiallyChangedCommand(DBObject command) {
 
-		Document result = new Document(command);
+		DBObject result = new BasicDBObject(command.toMap());
 
-		if (allowDiskUse && !result.containsKey(ALLOW_DISK_USE)) {
+		if (allowDiskUse && !result.containsField(ALLOW_DISK_USE)) {
 			result.put(ALLOW_DISK_USE, allowDiskUse);
 		}
 
-		if (explain && !result.containsKey(EXPLAIN)) {
+		if (explain && !result.containsField(EXPLAIN)) {
 			result.put(EXPLAIN, explain);
 		}
 
-		if (cursor != null && !result.containsKey(CURSOR)) {
+		if (cursor != null && !result.containsField(CURSOR)) {
 			result.put("cursor", cursor);
 		}
 
@@ -108,18 +108,18 @@ public class AggregationOptions {
 	}
 
 	/**
-	 * Returns a {@link Document} representation of this {@link AggregationOptions}.
+	 * Returns a {@link DBObject} representation of this {@link AggregationOptions}.
 	 * 
 	 * @return
 	 */
-	public Document toDocument() {
+	public DBObject toDbObject() {
 
-		Document document = new Document();
-		document.put(ALLOW_DISK_USE, allowDiskUse);
-		document.put(EXPLAIN, explain);
-		document.put(CURSOR, cursor);
+		DBObject dbo = new BasicDBObject();
+		dbo.put(ALLOW_DISK_USE, allowDiskUse);
+		dbo.put(EXPLAIN, explain);
+		dbo.put(CURSOR, cursor);
 
-		return document;
+		return dbo;
 	}
 
 	/* (non-Javadoc)
@@ -127,7 +127,7 @@ public class AggregationOptions {
 	 */
 	@Override
 	public String toString() {
-		return toDocument().toJson();
+		return toDbObject().toString();
 	}
 
 	/**
@@ -139,7 +139,7 @@ public class AggregationOptions {
 
 		private boolean allowDiskUse;
 		private boolean explain;
-		private Document cursor;
+		private DBObject cursor;
 
 		/**
 		 * Defines whether to off-load intensive sort-operations to disk.
@@ -171,7 +171,7 @@ public class AggregationOptions {
 		 * @param cursor
 		 * @return
 		 */
-		public Builder cursor(Document cursor) {
+		public Builder cursor(DBObject cursor) {
 
 			this.cursor = cursor;
 			return this;

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/AggregationResults.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2016 the original author or authors.
+ * Copyright 2013-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,23 +19,24 @@ import java.util.Collections;
 import java.util.Iterator;
 import java.util.List;
 
-import org.bson.Document;
 import org.springframework.util.Assert;
 
+import com.mongodb.DBObject;
+
 /**
  * Collects the results of executing an aggregation operation.
  * 
  * @author Tobias Trelle
  * @author Oliver Gierke
  * @author Thomas Darimont
- * @author Christoph Strobl
+ * @author Mark Paluch
  * @param <T> The class in which the results are mapped onto.
  * @since 1.3
  */
 public class AggregationResults<T> implements Iterable<T> {
 
 	private final List<T> mappedResults;
-	private final Document rawResults;
+	private final DBObject rawResults;
 	private final String serverUsed;
 
 	/**
@@ -44,10 +45,10 @@ public class AggregationResults<T> implements Iterable<T> {
 	 * @param mappedResults must not be {@literal null}.
 	 * @param rawResults must not be {@literal null}.
 	 */
-	public AggregationResults(List<T> mappedResults, Document rawResults) {
+	public AggregationResults(List<T> mappedResults, DBObject rawResults) {
 
-		Assert.notNull(mappedResults);
-		Assert.notNull(rawResults);
+		Assert.notNull(mappedResults, "List of mapped results must not be null!");
+		Assert.notNull(rawResults, "Raw results must not be null!");
 
 		this.mappedResults = Collections.unmodifiableList(mappedResults);
 		this.rawResults = rawResults;
@@ -97,7 +98,7 @@ public class AggregationResults<T> implements Iterable<T> {
 	 * @return
 	 * @since 1.6
 	 */
-	public Document getRawResults() {
+	public DBObject getRawResults() {
 		return rawResults;
 	}
 

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/AggregationSpELExpression.java

@@ -0,0 +1,74 @@
+/*
+ * Copyright 2016. the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb.core.aggregation;
+
+import org.springframework.util.Assert;
+
+import com.mongodb.DBObject;
+
+/**
+ * An {@link AggregationExpression} that renders a MongoDB Aggregation Framework expression from the AST of a
+ * <a href="http://docs.spring.io/spring/docs/current/spring-framework-reference/html/expressions.html">SpEL
+ * expression</a>. <br />
+ * <br />
+ * <strong>Samples:</strong> <br />
+ * <code>
+ * <pre>
+ * // { $and: [ { $gt: [ "$qty", 100 ] }, { $lt: [ "$qty", 250 ] } ] }
+ * expressionOf("qty > 100 && qty < 250);
+ *
+ * // { $cond : { if : { $gte : [ "$a", 42 ]}, then : "answer", else : "no-answer" } }
+ * expressionOf("cond(a >= 42, 'answer', 'no-answer')");
+ * </pre>
+ * </code>
+ * 
+ * @author Christoph Strobl
+ * @see SpelExpressionTransformer
+ * @since 1.10
+ */
+public class AggregationSpELExpression implements AggregationExpression {
+
+	private static final SpelExpressionTransformer TRANSFORMER = new SpelExpressionTransformer();
+	private final String rawExpression;
+	private final Object[] parameters;
+
+	private AggregationSpELExpression(String rawExpression, Object[] parameters) {
+
+		this.rawExpression = rawExpression;
+		this.parameters = parameters;
+	}
+
+	/**
+	 * Creates new {@link AggregationSpELExpression} for the given {@literal expressionString} and {@literal parameters}.
+	 *
+	 * @param expressionString must not be {@literal null}.
+	 * @param parameters can be empty.
+	 * @return
+	 */
+	public static AggregationSpELExpression expressionOf(String expressionString, Object... parameters) {
+
+		Assert.notNull(expressionString, "ExpressionString must not be null!");
+		return new AggregationSpELExpression(expressionString, parameters);
+	}
+
+	/* (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.AggregationExpression#toDbObject(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
+	 */
+	@Override
+	public DBObject toDbObject(AggregationOperationContext context) {
+		return (DBObject) TRANSFORMER.transform(rawExpression, context, parameters);
+	}
+}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/BooleanOperators.java

@@ -0,0 +1,353 @@
+/*
+ * Copyright 2016. the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb.core.aggregation;
+
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+
+import org.springframework.util.Assert;
+
+/**
+ * Gateway to {@literal boolean expressions} that evaluate their argument expressions as booleans and return a boolean
+ * as the result.
+ *
+ * @author Christoph Strobl
+ * @since 1.10
+ */
+public class BooleanOperators {
+
+	/**
+	 * Take the array referenced by given {@literal fieldReference}.
+	 *
+	 * @param fieldReference must not be {@literal null}.
+	 * @return
+	 */
+	public static BooleanOperatorFactory valueOf(String fieldReference) {
+		return new BooleanOperatorFactory(fieldReference);
+	}
+
+	/**
+	 * Take the value resulting of the given {@link AggregationExpression}.
+	 *
+	 * @param fieldReference must not be {@literal null}.
+	 * @return
+	 */
+	public static BooleanOperatorFactory valueOf(AggregationExpression fieldReference) {
+		return new BooleanOperatorFactory(fieldReference);
+	}
+
+	/**
+	 * Creates new {@link AggregationExpression} that evaluates the boolean value of the referenced field and returns the
+	 * opposite boolean value.
+	 *
+	 * @param fieldReference must not be {@literal null}.
+	 * @return
+	 */
+	public static Not not(String fieldReference) {
+		return Not.not(fieldReference);
+	}
+
+	/**
+	 * Creates new {@link AggregationExpression} that evaluates the boolean value of {@link AggregationExpression} result
+	 * and returns the opposite boolean value.
+	 *
+	 * @param expression must not be {@literal null}.
+	 * @return
+	 */
+	public static Not not(AggregationExpression expression) {
+		return Not.not(expression);
+	}
+
+	/**
+	 * @author Christoph Strobl
+	 */
+	public static class BooleanOperatorFactory {
+
+		private final String fieldReference;
+		private final AggregationExpression expression;
+
+		/**
+		 * Creates new {@link BooleanOperatorFactory} for given {@literal fieldReference}.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 */
+		public BooleanOperatorFactory(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			this.fieldReference = fieldReference;
+			this.expression = null;
+		}
+
+		/**
+		 * Creates new {@link BooleanOperatorFactory} for given {@link AggregationExpression}.
+		 *
+		 * @param expression must not be {@literal null}.
+		 */
+		public BooleanOperatorFactory(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			this.fieldReference = null;
+			this.expression = expression;
+		}
+
+		/**
+		 * Creates new {@link AggregationExpression} that evaluates one or more expressions and returns {@literal true} if
+		 * all of the expressions are {@literal true}.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public And and(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return createAnd().andExpression(expression);
+		}
+
+		/**
+		 * Creates new {@link AggregationExpression} that evaluates one or more expressions and returns {@literal true} if
+		 * all of the expressions are {@literal true}.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public And and(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			return createAnd().andField(fieldReference);
+		}
+
+		private And createAnd() {
+			return usesFieldRef() ? And.and(Fields.field(fieldReference)) : And.and(expression);
+		}
+
+		/**
+		 * Creates new {@link AggregationExpression} that evaluates one or more expressions and returns {@literal true} if
+		 * any of the expressions are {@literal true}.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public Or or(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return createOr().orExpression(expression);
+		}
+
+		/**
+		 * Creates new {@link AggregationExpression} that evaluates one or more expressions and returns {@literal true} if
+		 * any of the expressions are {@literal true}.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public Or or(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			return createOr().orField(fieldReference);
+		}
+
+		private Or createOr() {
+			return usesFieldRef() ? Or.or(Fields.field(fieldReference)) : Or.or(expression);
+		}
+
+		/**
+		 * Creates new {@link AggregationExpression} that evaluates a boolean and returns the opposite boolean value.
+		 *
+		 * @return
+		 */
+		public Not not() {
+			return usesFieldRef() ? Not.not(fieldReference) : Not.not(expression);
+		}
+
+		private boolean usesFieldRef() {
+			return this.fieldReference != null;
+		}
+	}
+
+	/**
+	 * {@link AggregationExpression} for {@code $and}.
+	 *
+	 * @author Christoph Strobl
+	 */
+	public static class And extends AbstractAggregationExpression {
+
+		private And(List<?> values) {
+			super(values);
+		}
+
+		@Override
+		protected String getMongoMethod() {
+			return "$and";
+		}
+
+		/**
+		 * Creates new {@link And} that evaluates one or more expressions and returns {@literal true} if all of the
+		 * expressions are {@literal true}.
+		 *
+		 * @param expressions
+		 * @return
+		 */
+		public static And and(Object... expressions) {
+			return new And(Arrays.asList(expressions));
+		}
+
+		/**
+		 * Creates new {@link And} with all previously added arguments appending the given one.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public And andExpression(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return new And(append(expression));
+		}
+
+		/**
+		 * Creates new {@link And} with all previously added arguments appending the given one.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public And andField(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			return new And(append(Fields.field(fieldReference)));
+		}
+
+		/**
+		 * Creates new {@link And} with all previously added arguments appending the given one.
+		 *
+		 * @param value must not be {@literal null}.
+		 * @return
+		 */
+		public And andValue(Object value) {
+
+			Assert.notNull(value, "Value must not be null!");
+			return new And(append(value));
+		}
+	}
+
+	/**
+	 * {@link AggregationExpression} for {@code $or}.
+	 *
+	 * @author Christoph Strobl
+	 */
+	public static class Or extends AbstractAggregationExpression {
+
+		private Or(List<?> values) {
+			super(values);
+		}
+
+		@Override
+		protected String getMongoMethod() {
+			return "$or";
+		}
+
+		/**
+		 * Creates new {@link Or} that evaluates one or more expressions and returns {@literal true} if any of the
+		 * expressions are {@literal true}.
+		 *
+		 * @param expressions must not be {@literal null}.
+		 * @return
+		 */
+		public static Or or(Object... expressions) {
+
+			Assert.notNull(expressions, "Expressions must not be null!");
+			return new Or(Arrays.asList(expressions));
+		}
+
+		/**
+		 * Creates new {@link Or} with all previously added arguments appending the given one.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public Or orExpression(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return new Or(append(expression));
+		}
+
+		/**
+		 * Creates new {@link Or} with all previously added arguments appending the given one.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public Or orField(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			return new Or(append(Fields.field(fieldReference)));
+		}
+
+		/**
+		 * Creates new {@link Or} with all previously added arguments appending the given one.
+		 *
+		 * @param value must not be {@literal null}.
+		 * @return
+		 */
+		public Or orValue(Object value) {
+
+			Assert.notNull(value, "Value must not be null!");
+			return new Or(append(value));
+		}
+	}
+
+	/**
+	 * {@link AggregationExpression} for {@code $not}.
+	 *
+	 * @author Christoph Strobl
+	 */
+	public static class Not extends AbstractAggregationExpression {
+
+		private Not(Object value) {
+			super(value);
+		}
+
+		@Override
+		protected String getMongoMethod() {
+			return "$not";
+		}
+
+		/**
+		 * Creates new {@link Not} that evaluates the boolean value of the referenced field and returns the opposite boolean
+		 * value.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public static Not not(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			return new Not(asFields(fieldReference));
+		}
+
+		/**
+		 * Creates new {@link Not} that evaluates the resulting boolean value of the given {@link AggregationExpression} and
+		 * returns the opposite boolean value.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public static Not not(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return new Not(Collections.singletonList(expression));
+		}
+	}
+}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/BucketAutoOperation.java

@@ -0,0 +1,275 @@
+/*
+ * Copyright 2016 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb.core.aggregation;
+
+import org.springframework.data.mongodb.core.aggregation.BucketAutoOperation.BucketAutoOperationOutputBuilder;
+import org.springframework.data.mongodb.core.aggregation.BucketOperationSupport.OutputBuilder;
+import org.springframework.util.Assert;
+
+import com.mongodb.BasicDBObject;
+import com.mongodb.DBObject;
+
+/**
+ * Encapsulates the aggregation framework {@code $bucketAuto}-operation. <br />
+ * Bucket stage is typically used with {@link Aggregation} and {@code $facet}. Categorizes incoming documents into a
+ * specific number of groups, called buckets, based on a specified expression. Bucket boundaries are automatically
+ * determined in an attempt to evenly distribute the documents into the specified number of buckets. <br />
+ * We recommend to use the static factory method {@link Aggregation#bucketAuto(String, int)} instead of creating
+ * instances of this class directly.
+ *
+ * @see <a href=
+ *      "https://docs.mongodb.org/manual/reference/aggregation/bucketAuto/">https://docs.mongodb.org/manual/reference/aggregation/bucketAuto/</a>
+ * @see BucketOperationSupport
+ * @author Mark Paluch
+ * @author Christoph Strobl
+ * @since 1.10
+ */
+public class BucketAutoOperation extends BucketOperationSupport<BucketAutoOperation, BucketAutoOperationOutputBuilder>
+		implements FieldsExposingAggregationOperation {
+
+	private final int buckets;
+	private final String granularity;
+
+	/**
+	 * Creates a new {@link BucketAutoOperation} given a {@link Field group-by field}.
+	 *
+	 * @param groupByField must not be {@literal null}.
+	 * @param buckets number of buckets, must be a positive integer.
+	 */
+	public BucketAutoOperation(Field groupByField, int buckets) {
+
+		super(groupByField);
+
+		Assert.isTrue(buckets > 0, "Number of buckets must be greater 0!");
+
+		this.buckets = buckets;
+		this.granularity = null;
+	}
+
+	/**
+	 * Creates a new {@link BucketAutoOperation} given a {@link AggregationExpression group-by expression}.
+	 *
+	 * @param groupByExpression must not be {@literal null}.
+	 * @param buckets number of buckets, must be a positive integer.
+	 */
+	public BucketAutoOperation(AggregationExpression groupByExpression, int buckets) {
+
+		super(groupByExpression);
+
+		Assert.isTrue(buckets > 0, "Number of buckets must be greater 0!");
+
+		this.buckets = buckets;
+		this.granularity = null;
+	}
+
+	private BucketAutoOperation(BucketAutoOperation bucketOperation, Outputs outputs) {
+
+		super(bucketOperation, outputs);
+
+		this.buckets = bucketOperation.buckets;
+		this.granularity = bucketOperation.granularity;
+	}
+
+	private BucketAutoOperation(BucketAutoOperation bucketOperation, int buckets, String granularity) {
+
+		super(bucketOperation);
+
+		this.buckets = buckets;
+		this.granularity = granularity;
+	}
+
+	/* (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.BucketOperationSupport#toDBObject(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
+	 */
+	@Override
+	public DBObject toDBObject(AggregationOperationContext context) {
+
+		DBObject options = new BasicDBObject();
+
+		options.put("buckets", buckets);
+		options.putAll(super.toDBObject(context));
+
+		if (granularity != null) {
+			options.put("granularity", granularity);
+		}
+
+		return new BasicDBObject("$bucketAuto", options);
+	}
+
+	/**
+	 * Configures a number of bucket {@literal buckets} and return a new {@link BucketAutoOperation}.
+	 *
+	 * @param buckets must be a positive number.
+	 * @return
+	 */
+	public BucketAutoOperation withBuckets(int buckets) {
+
+		Assert.isTrue(buckets > 0, "Number of buckets must be greater 0!");
+		return new BucketAutoOperation(this, buckets, granularity);
+	}
+
+	/**
+	 * Configures {@link Granularity granularity} that specifies the preferred number series to use to ensure that the
+	 * calculated boundary edges end on preferred round numbers or their powers of 10 and return a new
+	 * {@link BucketAutoOperation}. <br />
+	 * Use either predefined {@link Granularities} or provide a own one.
+	 *
+	 * @param granularity must not be {@literal null}.
+	 * @return
+	 */
+	public BucketAutoOperation withGranularity(Granularity granularity) {
+
+		Assert.notNull(granularity, "Granularity must not be null!");
+
+		return new BucketAutoOperation(this, buckets, granularity.getMongoRepresentation());
+	}
+
+	/* (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.BucketOperationSupport#newBucketOperation(org.springframework.data.mongodb.core.aggregation.BucketOperationSupport.Outputs)
+	 */
+	@Override
+	protected BucketAutoOperation newBucketOperation(Outputs outputs) {
+		return new BucketAutoOperation(this, outputs);
+	}
+
+	/* (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.BucketOperationSupport#andOutputExpression(java.lang.String, java.lang.Object[])
+	 */
+	@Override
+	public ExpressionBucketAutoOperationBuilder andOutputExpression(String expression, Object... params) {
+		return new ExpressionBucketAutoOperationBuilder(expression, this, params);
+	}
+
+	/* (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.BucketOperationSupport#andOutput(org.springframework.data.mongodb.core.aggregation.AggregationExpression)
+	 */
+	@Override
+	public BucketAutoOperationOutputBuilder andOutput(AggregationExpression expression) {
+		return new BucketAutoOperationOutputBuilder(expression, this);
+	}
+
+	/* (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.BucketOperationSupport#andOutput(java.lang.String)
+	 */
+	@Override
+	public BucketAutoOperationOutputBuilder andOutput(String fieldName) {
+		return new BucketAutoOperationOutputBuilder(Fields.field(fieldName), this);
+	}
+
+	/**
+	 * {@link OutputBuilder} implementation for {@link BucketAutoOperation}.
+	 */
+	public static class BucketAutoOperationOutputBuilder
+			extends OutputBuilder<BucketAutoOperationOutputBuilder, BucketAutoOperation> {
+
+		/**
+		 * Creates a new {@link BucketAutoOperationOutputBuilder} fot the given value and {@link BucketAutoOperation}.
+		 *
+		 * @param value must not be {@literal null}.
+		 * @param operation must not be {@literal null}.
+		 */
+		protected BucketAutoOperationOutputBuilder(Object value, BucketAutoOperation operation) {
+			super(value, operation);
+		}
+
+		/* (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.BucketOperationSupport.OutputBuilder#apply(org.springframework.data.mongodb.core.aggregation.BucketOperationSupport.OperationOutput)
+		 */
+		@Override
+		protected BucketAutoOperationOutputBuilder apply(OperationOutput operationOutput) {
+			return new BucketAutoOperationOutputBuilder(operationOutput, this.operation);
+		}
+	}
+
+	/**
+	 * {@link ExpressionBucketOperationBuilderSupport} implementation for {@link BucketAutoOperation} using SpEL
+	 * expression based {@link Output}.
+	 *
+	 * @author Mark Paluch
+	 */
+	public static class ExpressionBucketAutoOperationBuilder
+			extends ExpressionBucketOperationBuilderSupport<BucketAutoOperationOutputBuilder, BucketAutoOperation> {
+
+		/**
+		 * Creates a new {@link ExpressionBucketAutoOperationBuilder} for the given value, {@link BucketAutoOperation} and
+		 * parameters.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @param operation must not be {@literal null}.
+		 * @param parameters
+		 */
+		protected ExpressionBucketAutoOperationBuilder(String expression, BucketAutoOperation operation,
+				Object[] parameters) {
+			super(expression, operation, parameters);
+		}
+
+		/* (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.BucketOperationSupport.OutputBuilder#apply(org.springframework.data.mongodb.core.aggregation.BucketOperationSupport.OperationOutput)
+		 */
+		@Override
+		protected BucketAutoOperationOutputBuilder apply(OperationOutput operationOutput) {
+			return new BucketAutoOperationOutputBuilder(operationOutput, this.operation);
+		}
+	}
+
+	/**
+	 * @author Mark Paluch
+	 */
+	public interface Granularity {
+
+		/**
+		 * @return a String that represents a MongoDB granularity to be used with {@link BucketAutoOperation}. Never
+		 *         {@literal null}.
+		 */
+		String getMongoRepresentation();
+	}
+
+	/**
+	 * Supported MongoDB granularities.
+	 *
+	 * @see <a
+	 *      href="https://docs.mongodb.com/manual/reference/operator/aggregation/bucketAuto/#granularity>https://docs.mongodb.com/manual/reference/operator/aggregation/bucketAuto/#granularity</a>
+	 * @author Mark Paluch
+	 */
+	public enum Granularities implements Granularity {
+
+		R5, R10, R20, R40, R80, //
+
+		SERIES_1_2_5("1-2-5"), //
+
+		E6, E12, E24, E48, E96, E192, //
+
+		POWERSOF2;
+
+		private final String granularity;
+
+		Granularities() {
+			this.granularity = name();
+		}
+
+		Granularities(String granularity) {
+			this.granularity = granularity;
+		}
+
+		/* (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.GranularitytoMongoGranularity()
+		 */
+		@Override
+		public String getMongoRepresentation() {
+			return granularity;
+		}
+	}
+}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/BucketOperation.java

@@ -0,0 +1,227 @@
+/*
+ * Copyright 2016 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb.core.aggregation;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+
+import org.springframework.data.mongodb.core.aggregation.BucketOperation.BucketOperationOutputBuilder;
+import org.springframework.util.Assert;
+
+import com.mongodb.BasicDBObject;
+import com.mongodb.DBObject;
+
+/**
+ * Encapsulates the aggregation framework {@code $bucket}-operation. <br />
+ *
+ * Bucket stage is typically used with {@link Aggregation} and {@code $facet}. Categorizes incoming documents into
+ * groups, called buckets, based on a specified expression and bucket boundaries. <br />
+ *
+ * We recommend to use the static factory method {@link Aggregation#bucket(String)} instead of creating instances of
+ * this class directly.
+ *
+ * @see <a href="https://docs.mongodb.org/manual/reference/aggregation/bucket/">https://docs.mongodb.org/manual/reference/aggregation/bucket/</a>
+ * @see BucketOperationSupport
+ * @author Mark Paluch
+ * @since 1.10
+ */
+public class BucketOperation extends BucketOperationSupport<BucketOperation, BucketOperationOutputBuilder>
+		implements FieldsExposingAggregationOperation {
+
+	private final List<Object> boundaries;
+	private final Object defaultBucket;
+
+	/**
+	 * Creates a new {@link BucketOperation} given a {@link Field group-by field}.
+	 *
+	 * @param groupByField must not be {@literal null}.
+	 */
+	public BucketOperation(Field groupByField) {
+
+		super(groupByField);
+
+		this.boundaries = Collections.emptyList();
+		this.defaultBucket = null;
+	}
+
+	/**
+	 * Creates a new {@link BucketOperation} given a {@link AggregationExpression group-by expression}.
+	 *
+	 * @param groupByExpression must not be {@literal null}.
+	 */
+	public BucketOperation(AggregationExpression groupByExpression) {
+
+		super(groupByExpression);
+
+		this.boundaries = Collections.emptyList();
+		this.defaultBucket = null;
+	}
+
+	private BucketOperation(BucketOperation bucketOperation, Outputs outputs) {
+
+		super(bucketOperation, outputs);
+
+		this.boundaries = bucketOperation.boundaries;
+		this.defaultBucket = bucketOperation.defaultBucket;
+	}
+
+	private BucketOperation(BucketOperation bucketOperation, List<Object> boundaries, Object defaultBucket) {
+
+		super(bucketOperation);
+
+		this.boundaries = new ArrayList<Object>(boundaries);
+		this.defaultBucket = defaultBucket;
+	}
+
+	/* (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.BucketOperationSupport#toDBObject(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
+	 */
+	@Override
+	public DBObject toDBObject(AggregationOperationContext context) {
+
+		DBObject options = new BasicDBObject();
+
+		options.put("boundaries", context.getMappedObject(new BasicDBObject("$set", boundaries)).get("$set"));
+
+		if (defaultBucket != null) {
+			options.put("default", context.getMappedObject(new BasicDBObject("$set", defaultBucket)).get("$set"));
+		}
+
+		options.putAll(super.toDBObject(context));
+
+		return new BasicDBObject("$bucket", options);
+	}
+
+	/**
+	 * Configures a default bucket {@literal literal} and return a new {@link BucketOperation}.
+	 *
+	 * @param literal must not be {@literal null}.
+	 * @return
+	 */
+	public BucketOperation withDefaultBucket(Object literal) {
+
+		Assert.notNull(literal, "Default bucket literal must not be null!");
+		return new BucketOperation(this, boundaries, literal);
+	}
+
+	/**
+	 * Configures {@literal boundaries} and return a new {@link BucketOperation}. Existing {@literal boundaries} are
+	 * preserved and the new {@literal boundaries} are appended.
+	 *
+	 * @param boundaries must not be {@literal null}.
+	 * @return
+	 */
+	public BucketOperation withBoundaries(Object... boundaries) {
+
+		Assert.notNull(boundaries, "Boundaries must not be null!");
+		Assert.noNullElements(boundaries, "Boundaries must not contain null values!");
+
+		List<Object> newBoundaries = new ArrayList<Object>(this.boundaries.size() + boundaries.length);
+		newBoundaries.addAll(this.boundaries);
+		newBoundaries.addAll(Arrays.asList(boundaries));
+
+		return new BucketOperation(this, newBoundaries, defaultBucket);
+	}
+
+	/* (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.BucketOperationSupport#newBucketOperation(org.springframework.data.mongodb.core.aggregation.BucketOperationSupport.Outputs)
+	 */
+	@Override
+	protected BucketOperation newBucketOperation(Outputs outputs) {
+		return new BucketOperation(this, outputs);
+	}
+
+	/* (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.BucketOperationSupport#andOutputExpression(java.lang.String, java.lang.Object[])
+	 */
+	@Override
+	public ExpressionBucketOperationBuilder andOutputExpression(String expression, Object... params) {
+		return new ExpressionBucketOperationBuilder(expression, this, params);
+	}
+
+	/* (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.BucketOperationSupport#andOutput(org.springframework.data.mongodb.core.aggregation.AggregationExpression)
+	 */
+	@Override
+	public BucketOperationOutputBuilder andOutput(AggregationExpression expression) {
+		return new BucketOperationOutputBuilder(expression, this);
+	}
+
+	/* (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.BucketOperationSupport#andOutput(java.lang.String)
+	 */
+	@Override
+	public BucketOperationOutputBuilder andOutput(String fieldName) {
+		return new BucketOperationOutputBuilder(Fields.field(fieldName), this);
+	}
+
+	/**
+	 * {@link OutputBuilder} implementation for {@link BucketOperation}.
+	 */
+	public static class BucketOperationOutputBuilder
+			extends BucketOperationSupport.OutputBuilder<BucketOperationOutputBuilder, BucketOperation> {
+
+		/**
+		 * Creates a new {@link BucketOperationOutputBuilder} fot the given value and {@link BucketOperation}.
+		 *
+		 * @param value must not be {@literal null}.
+		 * @param operation must not be {@literal null}.
+		 */
+		protected BucketOperationOutputBuilder(Object value, BucketOperation operation) {
+			super(value, operation);
+		}
+
+		/* (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.BucketOperationSupport.OutputBuilder#apply(org.springframework.data.mongodb.core.aggregation.BucketOperationSupport.OperationOutput)
+		 */
+		@Override
+		protected BucketOperationOutputBuilder apply(OperationOutput operationOutput) {
+			return new BucketOperationOutputBuilder(operationOutput, this.operation);
+		}
+	}
+
+	/**
+	 * {@link ExpressionBucketOperationBuilderSupport} implementation for {@link BucketOperation} using SpEL expression
+	 * based {@link Output}.
+	 *
+	 * @author Mark Paluch
+	 */
+	public static class ExpressionBucketOperationBuilder
+			extends ExpressionBucketOperationBuilderSupport<BucketOperationOutputBuilder, BucketOperation> {
+
+		/**
+		 * Creates a new {@link ExpressionBucketOperationBuilderSupport} for the given value, {@link BucketOperation}
+		 * and parameters.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @param operation must not be {@literal null}.
+		 * @param parameters
+		 */
+		protected ExpressionBucketOperationBuilder(String expression, BucketOperation operation, Object[] parameters) {
+			super(expression, operation, parameters);
+		}
+
+		/* (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.BucketOperationSupport.OutputBuilder#apply(org.springframework.data.mongodb.core.aggregation.BucketOperationSupport.OperationOutput)
+		 */
+		@Override
+		protected BucketOperationOutputBuilder apply(OperationOutput operationOutput) {
+			return new BucketOperationOutputBuilder(operationOutput, this.operation);
+		}
+	}
+}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/BucketOperationSupport.java

@@ -0,0 +1,680 @@
+/*
+ * Copyright 2016 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb.core.aggregation;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+
+import org.springframework.data.mongodb.core.aggregation.BucketOperationSupport.OutputBuilder;
+import org.springframework.data.mongodb.core.aggregation.ExposedFields.ExposedField;
+import org.springframework.data.mongodb.core.aggregation.ProjectionOperation.ProjectionOperationBuilder;
+import org.springframework.expression.spel.ast.Projection;
+import org.springframework.util.Assert;
+
+import com.mongodb.BasicDBObject;
+import com.mongodb.DBObject;
+
+/**
+ * Base class for bucket operations that support output expressions the aggregation framework. <br />
+ * Bucket stages collect documents into buckets and can contribute output fields. <br />
+ * Implementing classes are required to provide an {@link OutputBuilder}.
+ *
+ * @author Mark Paluch
+ * @author Christoph Strobl
+ * @since 1.10
+ */
+public abstract class BucketOperationSupport<T extends BucketOperationSupport<T, B>, B extends OutputBuilder<B, T>>
+		implements FieldsExposingAggregationOperation {
+
+	private final Field groupByField;
+	private final AggregationExpression groupByExpression;
+	private final Outputs outputs;
+
+	/**
+	 * Creates a new {@link BucketOperationSupport} given a {@link Field group-by field}.
+	 *
+	 * @param groupByField must not be {@literal null}.
+	 */
+	protected BucketOperationSupport(Field groupByField) {
+
+		Assert.notNull(groupByField, "Group by field must not be null!");
+
+		this.groupByField = groupByField;
+		this.groupByExpression = null;
+		this.outputs = Outputs.EMPTY;
+	}
+
+	/**
+	 * Creates a new {@link BucketOperationSupport} given a {@link AggregationExpression group-by expression}.
+	 *
+	 * @param groupByExpression must not be {@literal null}.
+	 */
+	protected BucketOperationSupport(AggregationExpression groupByExpression) {
+
+		Assert.notNull(groupByExpression, "Group by AggregationExpression must not be null!");
+
+		this.groupByExpression = groupByExpression;
+		this.groupByField = null;
+		this.outputs = Outputs.EMPTY;
+	}
+
+	/**
+	 * Creates a copy of {@link BucketOperationSupport}.
+	 *
+	 * @param operationSupport must not be {@literal null}.
+	 */
+	protected BucketOperationSupport(BucketOperationSupport<?, ?> operationSupport) {
+		this(operationSupport, operationSupport.outputs);
+	}
+
+	/**
+	 * Creates a copy of {@link BucketOperationSupport} and applies the new {@link Outputs}.
+	 *
+	 * @param operationSupport must not be {@literal null}.
+	 * @param outputs must not be {@literal null}.
+	 */
+	protected BucketOperationSupport(BucketOperationSupport<?, ?> operationSupport, Outputs outputs) {
+
+		Assert.notNull(operationSupport, "BucketOperationSupport must not be null!");
+		Assert.notNull(outputs, "Outputs must not be null!");
+
+		this.groupByField = operationSupport.groupByField;
+		this.groupByExpression = operationSupport.groupByExpression;
+		this.outputs = outputs;
+	}
+
+	/**
+	 * Creates a new {@link ExpressionBucketOperationBuilderSupport} given a SpEL {@literal expression} and optional
+	 * {@literal params} to add an output field to the resulting bucket documents.
+	 *
+	 * @param expression the SpEL expression, must not be {@literal null} or empty.
+	 * @param params must not be {@literal null}
+	 * @return
+	 */
+	public abstract ExpressionBucketOperationBuilderSupport<B, T> andOutputExpression(String expression,
+			Object... params);
+
+	/**
+	 * Creates a new {@link BucketOperationSupport} given an {@link AggregationExpression} to add an output field to the
+	 * resulting bucket documents.
+	 *
+	 * @param expression the SpEL expression, must not be {@literal null} or empty.
+	 * @return
+	 */
+	public abstract B andOutput(AggregationExpression expression);
+
+	/**
+	 * Creates a new {@link BucketOperationSupport} given {@literal fieldName} to add an output field to the resulting
+	 * bucket documents. {@link BucketOperationSupport} exposes accumulation operations that can be applied to
+	 * {@literal fieldName}.
+	 *
+	 * @param fieldName must not be {@literal null} or empty.
+	 * @return
+	 */
+	public abstract B andOutput(String fieldName);
+
+	/**
+	 * Creates a new {@link BucketOperationSupport} given to add a count field to the resulting bucket documents.
+	 *
+	 * @return
+	 */
+	public B andOutputCount() {
+		return andOutput(new AggregationExpression() {
+			@Override
+			public DBObject toDbObject(AggregationOperationContext context) {
+				return new BasicDBObject("$sum", 1);
+			}
+		});
+	}
+
+	/* (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperation#toDBObject(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
+	 */
+	@Override
+	public DBObject toDBObject(AggregationOperationContext context) {
+
+		DBObject dbObject = new BasicDBObject();
+
+		dbObject.put("groupBy", groupByExpression == null ? context.getReference(groupByField).toString()
+				: groupByExpression.toDbObject(context));
+
+		if (!outputs.isEmpty()) {
+			dbObject.put("output", outputs.toDbObject(context));
+		}
+
+		return dbObject;
+	}
+
+	/* (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.FieldsExposingAggregationOperation#getFields()
+	 */
+	@Override
+	public ExposedFields getFields() {
+		return outputs.asExposedFields();
+	}
+
+	/**
+	 * Implementation hook to create a new bucket operation.
+	 *
+	 * @param outputs the outputs
+	 * @return the new bucket operation.
+	 */
+	protected abstract T newBucketOperation(Outputs outputs);
+
+	protected T andOutput(Output output) {
+		return newBucketOperation(outputs.and(output));
+	}
+
+	/**
+	 * Builder for SpEL expression-based {@link Output}.
+	 *
+	 * @author Mark Paluch
+	 */
+	public abstract static class ExpressionBucketOperationBuilderSupport<B extends OutputBuilder<B, T>, T extends BucketOperationSupport<T, B>>
+			extends OutputBuilder<B, T> {
+
+		/**
+		 * Creates a new {@link ExpressionBucketOperationBuilderSupport} for the given value, {@link BucketOperationSupport}
+		 * and parameters.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @param operation must not be {@literal null}.
+		 * @param parameters
+		 */
+		protected ExpressionBucketOperationBuilderSupport(String expression, T operation, Object[] parameters) {
+			super(new SpelExpressionOutput(expression, parameters), operation);
+		}
+	}
+
+	/**
+	 * Base class for {@link Output} builders that result in a {@link BucketOperationSupport} providing the built
+	 * {@link Output}.
+	 *
+	 * @author Mark Paluch
+	 */
+	public abstract static class OutputBuilder<B extends OutputBuilder<B, T>, T extends BucketOperationSupport<T, B>> {
+
+		protected final Object value;
+		protected final T operation;
+
+		/**
+		 * Creates a new {@link OutputBuilder} for the given value and {@link BucketOperationSupport}.
+		 *
+		 * @param value must not be {@literal null}.
+		 * @param operation must not be {@literal null}.
+		 */
+		protected OutputBuilder(Object value, T operation) {
+
+			Assert.notNull(value, "Value must not be null or empty!");
+			Assert.notNull(operation, "ProjectionOperation must not be null!");
+
+			this.value = value;
+			this.operation = operation;
+		}
+
+		/**
+		 * Generates a builder for a {@code $sum}-expression. <br />
+		 * Count expressions are emulated via {@code $sum: 1}.
+		 *
+		 * @return
+		 */
+		public B count() {
+			return sum(1);
+		}
+
+		/**
+		 * Generates a builder for a {@code $sum}-expression for the current value.
+		 *
+		 * @return
+		 */
+		public B sum() {
+			return apply(Accumulators.SUM);
+		}
+
+		/**
+		 * Generates a builder for a {@code $sum}-expression for the given {@literal value}.
+		 *
+		 * @param value
+		 * @return
+		 */
+		public B sum(Number value) {
+			return apply(new OperationOutput(Accumulators.SUM.getMongoOperator(), Collections.singleton(value)));
+		}
+
+		/**
+		 * Generates a builder for an {@code $last}-expression for the current value..
+		 *
+		 * @return
+		 */
+		public B last() {
+			return apply(Accumulators.LAST);
+		}
+
+		/**
+		 * Generates a builder for a {@code $first}-expression the current value.
+		 *
+		 * @return
+		 */
+		public B first() {
+			return apply(Accumulators.FIRST);
+		}
+
+		/**
+		 * Generates a builder for an {@code $avg}-expression for the current value.
+		 *
+		 * @param reference
+		 * @return
+		 */
+		public B avg() {
+			return apply(Accumulators.AVG);
+		}
+
+		/**
+		 * Generates a builder for an {@code $min}-expression for the current value.
+		 *
+		 * @return
+		 */
+		public B min() {
+			return apply(Accumulators.MIN);
+		}
+
+		/**
+		 * Generates a builder for an {@code $max}-expression for the current value.
+		 *
+		 * @return
+		 */
+		public B max() {
+			return apply(Accumulators.MAX);
+		}
+
+		/**
+		 * Generates a builder for an {@code $push}-expression for the current value.
+		 *
+		 * @return
+		 */
+		public B push() {
+			return apply(Accumulators.PUSH);
+		}
+
+		/**
+		 * Generates a builder for an {@code $addToSet}-expression for the current value.
+		 *
+		 * @return
+		 */
+		public B addToSet() {
+			return apply(Accumulators.ADDTOSET);
+		}
+
+		/**
+		 * Apply an operator to the current value.
+		 *
+		 * @param operation the operation name, must not be {@literal null} or empty.
+		 * @param values must not be {@literal null}.
+		 * @return
+		 */
+		public B apply(String operation, Object... values) {
+
+			Assert.hasText(operation, "Operation must not be empty or null!");
+			Assert.notNull(value, "Values must not be null!");
+
+			List<Object> objects = new ArrayList<Object>(values.length + 1);
+			objects.add(value);
+			objects.addAll(Arrays.asList(values));
+			return apply(new OperationOutput(operation, objects));
+		}
+
+		/**
+		 * Apply an {@link OperationOutput} to this output.
+		 *
+		 * @param operationOutput must not be {@literal null}.
+		 * @return
+		 */
+		protected abstract B apply(OperationOutput operationOutput);
+
+		private B apply(Accumulators operation) {
+			return this.apply(operation.getMongoOperator());
+		}
+
+		/**
+		 * Returns the finally to be applied {@link BucketOperation} with the given alias.
+		 *
+		 * @param alias will never be {@literal null} or empty.
+		 * @return
+		 */
+		public T as(String alias) {
+
+			if (value instanceof OperationOutput) {
+				return this.operation.andOutput(((OperationOutput) this.value).withAlias(alias));
+			}
+
+			if (value instanceof Field) {
+				throw new IllegalStateException("Cannot add a field as top-level output. Use accumulator expressions.");
+			}
+
+			return this.operation
+					.andOutput(new AggregationExpressionOutput(Fields.field(alias), (AggregationExpression) value));
+		}
+	}
+
+	private enum Accumulators {
+
+		SUM("$sum"), AVG("$avg"), FIRST("$first"), LAST("$last"), MAX("$max"), MIN("$min"), PUSH("$push"), ADDTOSET(
+				"$addToSet");
+
+		private String mongoOperator;
+
+		Accumulators(String mongoOperator) {
+			this.mongoOperator = mongoOperator;
+		}
+
+		public String getMongoOperator() {
+			return mongoOperator;
+		}
+	}
+
+	/**
+	 * Encapsulates {@link Output}s.
+	 *
+	 * @author Mark Paluch
+	 */
+	protected static class Outputs implements AggregationExpression {
+
+		protected static final Outputs EMPTY = new Outputs();
+
+		private List<Output> outputs;
+
+		/**
+		 * Creates a new, empty {@link Outputs}.
+		 */
+		private Outputs() {
+			this.outputs = new ArrayList<Output>();
+		}
+
+		/**
+		 * Creates new {@link Outputs} containing all given {@link Output}s.
+		 *
+		 * @param current
+		 * @param output
+		 */
+		private Outputs(Collection<Output> current, Output output) {
+
+			this.outputs = new ArrayList<Output>(current.size() + 1);
+			this.outputs.addAll(current);
+			this.outputs.add(output);
+		}
+
+		/**
+		 * @return the {@link ExposedFields} derived from {@link Output}.
+		 */
+		protected ExposedFields asExposedFields() {
+
+			// The count field is included by default when the output is not specified.
+			if (isEmpty()) {
+				return ExposedFields.from(new ExposedField("count", true));
+			}
+
+			ExposedFields fields = ExposedFields.from();
+
+			for (Output output : outputs) {
+				fields = fields.and(output.getExposedField());
+			}
+
+			return fields;
+		}
+
+		/**
+		 * Create a new {@link Outputs} that contains the new {@link Output}.
+		 *
+		 * @param output must not be {@literal null}.
+		 * @return the new {@link Outputs} that contains the new {@link Output}
+		 */
+		protected Outputs and(Output output) {
+
+			Assert.notNull(output, "BucketOutput must not be null!");
+			return new Outputs(this.outputs, output);
+		}
+
+		/**
+		 * @return {@literal true} if {@link Outputs} contains no {@link Output}.
+		 */
+		protected boolean isEmpty() {
+			return outputs.isEmpty();
+		}
+
+		/* (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.AggregationExpression#toDbObject(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
+		 */
+		@Override
+		public DBObject toDbObject(AggregationOperationContext context) {
+
+			DBObject dbObject = new BasicDBObject();
+
+			for (Output output : outputs) {
+				dbObject.put(output.getExposedField().getName(), output.toDbObject(context));
+			}
+
+			return dbObject;
+		}
+
+	}
+
+	/**
+	 * Encapsulates an output field in a bucket aggregation stage. <br />
+	 * Output fields can be either top-level fields that define a valid field name or nested output fields using
+	 * operators.
+	 *
+	 * @author Mark Paluch
+	 */
+	protected abstract static class Output implements AggregationExpression {
+
+		private final ExposedField field;
+
+		/**
+		 * Creates new {@link Projection} for the given {@link Field}.
+		 *
+		 * @param field must not be {@literal null}.
+		 */
+		protected Output(Field field) {
+
+			Assert.notNull(field, "Field must not be null!");
+			this.field = new ExposedField(field, true);
+		}
+
+		/**
+		 * Returns the field exposed by the {@link Output}.
+		 *
+		 * @return will never be {@literal null}.
+		 */
+		protected ExposedField getExposedField() {
+			return field;
+		}
+	}
+
+	/**
+	 * Output field that uses a Mongo operation (expression object) to generate an output field value. <br />
+	 * {@link OperationOutput} is used either with a regular field name or an operation keyword (e.g.
+	 * {@literal $sum, $count}).
+	 *
+	 * @author Mark Paluch
+	 */
+	protected static class OperationOutput extends Output {
+
+		private final String operation;
+		private final List<Object> values;
+
+		/**
+		 * Creates a new {@link Output} for the given field.
+		 *
+		 * @param operation the actual operation key, must not be {@literal null} or empty.
+		 * @param values the values to pass into the operation, must not be {@literal null}.
+		 */
+		public OperationOutput(String operation, Collection<? extends Object> values) {
+
+			super(Fields.field(operation));
+
+			Assert.hasText(operation, "Operation must not be null or empty!");
+			Assert.notNull(values, "Values must not be null!");
+
+			this.operation = operation;
+			this.values = new ArrayList<Object>(values);
+		}
+
+		private OperationOutput(Field field, OperationOutput operationOutput) {
+
+			super(field);
+
+			this.operation = operationOutput.operation;
+			this.values = operationOutput.values;
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.ProjectionOperation.Projection#toDBObject(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
+		 */
+		@Override
+		public DBObject toDbObject(AggregationOperationContext context) {
+
+			List<Object> operationArguments = getOperationArguments(context);
+			return new BasicDBObject(operation,
+					operationArguments.size() == 1 ? operationArguments.get(0) : operationArguments);
+		}
+
+		protected List<Object> getOperationArguments(AggregationOperationContext context) {
+
+			List<Object> result = new ArrayList<Object>(values != null ? values.size() : 1);
+
+			for (Object element : values) {
+
+				if (element instanceof Field) {
+					result.add(context.getReference((Field) element).toString());
+				} else if (element instanceof Fields) {
+					for (Field field : (Fields) element) {
+						result.add(context.getReference(field).toString());
+					}
+				} else if (element instanceof AggregationExpression) {
+					result.add(((AggregationExpression) element).toDbObject(context));
+				} else {
+					result.add(element);
+				}
+			}
+
+			return result;
+		}
+
+		/**
+		 * Returns the field that holds the {@link ProjectionOperationBuilder.OperationProjection}.
+		 *
+		 * @return
+		 */
+		protected Field getField() {
+			return getExposedField();
+		}
+
+		/**
+		 * Creates a new instance of this {@link OperationOutput} with the given alias.
+		 *
+		 * @param alias the alias to set
+		 * @return
+		 */
+		public OperationOutput withAlias(String alias) {
+
+			final Field aliasedField = Fields.field(alias);
+			return new OperationOutput(aliasedField, this) {
+
+				@Override
+				protected Field getField() {
+					return aliasedField;
+				}
+
+				@Override
+				protected List<Object> getOperationArguments(AggregationOperationContext context) {
+
+					// We have to make sure that we use the arguments from the "previous" OperationOutput that we replace
+					// with this new instance.
+					return OperationOutput.this.getOperationArguments(context);
+				}
+			};
+		}
+	}
+
+	/**
+	 * A {@link Output} based on a SpEL expression.
+	 */
+	private static class SpelExpressionOutput extends Output {
+
+		private static final SpelExpressionTransformer TRANSFORMER = new SpelExpressionTransformer();
+
+		private final String expression;
+		private final Object[] params;
+
+		/**
+		 * Creates a new {@link SpelExpressionOutput} for the given field, SpEL expression and parameters.
+		 *
+		 * @param expression must not be {@literal null} or empty.
+		 * @param parameters must not be {@literal null}.
+		 */
+		public SpelExpressionOutput(String expression, Object[] parameters) {
+
+			super(Fields.field(expression));
+
+			Assert.hasText(expression, "Expression must not be null!");
+			Assert.notNull(parameters, "Parameters must not be null!");
+
+			this.expression = expression;
+			this.params = parameters.clone();
+		}
+
+		/* (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.BucketOperationSupport.Output#toDbObject(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
+		 */
+		@Override
+		public DBObject toDbObject(AggregationOperationContext context) {
+			return (DBObject) TRANSFORMER.transform(expression, context, params);
+		}
+	}
+
+	/**
+	 * @author Mark Paluch
+	 */
+	private static class AggregationExpressionOutput extends Output {
+
+		private final AggregationExpression expression;
+
+		/**
+		 * Creates a new {@link AggregationExpressionOutput}.
+		 *
+		 * @param field
+		 * @param expression
+		 */
+		protected AggregationExpressionOutput(Field field, AggregationExpression expression) {
+
+			super(field);
+
+			this.expression = expression;
+		}
+
+		/* (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.BucketOperationSupport.Output#toDbObject(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
+		 */
+		@Override
+		public DBObject toDbObject(AggregationOperationContext context) {
+			return expression.toDbObject(context);
+		}
+	}
+}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/ComparisonOperators.java

@@ -0,0 +1,879 @@
+/*
+ * Copyright 2016. the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb.core.aggregation;
+
+import java.util.Collections;
+import java.util.List;
+
+import org.springframework.util.Assert;
+
+/**
+ * Gateway to {@literal comparison expressions}.
+ *
+ * @author Christoph Strobl
+ * @since 1.10
+ */
+public class ComparisonOperators {
+
+	/**
+	 * Take the field referenced by given {@literal fieldReference}.
+	 *
+	 * @param fieldReference must not be {@literal null}.
+	 * @return
+	 */
+	public static ComparisonOperatorFactory valueOf(String fieldReference) {
+		return new ComparisonOperatorFactory(fieldReference);
+	}
+
+	/**
+	 * Take the value resulting from the given {@link AggregationExpression}.
+	 *
+	 * @param expression must not be {@literal null}.
+	 * @return
+	 */
+	public static ComparisonOperatorFactory valueOf(AggregationExpression expression) {
+		return new ComparisonOperatorFactory(expression);
+	}
+
+	public static class ComparisonOperatorFactory {
+
+		private final String fieldReference;
+		private final AggregationExpression expression;
+
+		/**
+		 * Creates new {@link ComparisonOperatorFactory} for given {@literal fieldReference}.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 */
+		public ComparisonOperatorFactory(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			this.fieldReference = fieldReference;
+			this.expression = null;
+		}
+
+		/**
+		 * Creates new {@link ComparisonOperatorFactory} for given {@link AggregationExpression}.
+		 *
+		 * @param expression must not be {@literal null}.
+		 */
+		public ComparisonOperatorFactory(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			this.fieldReference = null;
+			this.expression = expression;
+		}
+
+		/**
+		 * Creates new {@link AggregationExpression} that compares two values.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public Cmp compareTo(String fieldReference) {
+			return createCmp().compareTo(fieldReference);
+		}
+
+		/**
+		 * Creates new {@link AggregationExpression} that compares two values.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public Cmp compareTo(AggregationExpression expression) {
+			return createCmp().compareTo(expression);
+		}
+
+		/**
+		 * Creates new {@link AggregationExpression} that compares two values.
+		 *
+		 * @param value must not be {@literal null}.
+		 * @return
+		 */
+		public Cmp compareToValue(Object value) {
+			return createCmp().compareToValue(value);
+		}
+
+		private Cmp createCmp() {
+			return usesFieldRef() ? Cmp.valueOf(fieldReference) : Cmp.valueOf(expression);
+		}
+
+		/**
+		 * Creates new {@link AggregationExpression} that compares two values and returns {@literal true} when the first
+		 * value is equal to the value of the referenced field.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public Eq equalTo(String fieldReference) {
+			return createEq().equalTo(fieldReference);
+		}
+
+		/**
+		 * Creates new {@link AggregationExpression} that compares two values and returns {@literal true} when the first
+		 * value is equal to the expression result.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public Eq equalTo(AggregationExpression expression) {
+			return createEq().equalTo(expression);
+		}
+
+		/**
+		 * Creates new {@link AggregationExpression} that compares two values and returns {@literal true} when the first
+		 * value is equal to the given value.
+		 *
+		 * @param value must not be {@literal null}.
+		 * @return
+		 */
+		public Eq equalToValue(Object value) {
+			return createEq().equalToValue(value);
+		}
+
+		private Eq createEq() {
+			return usesFieldRef() ? Eq.valueOf(fieldReference) : Eq.valueOf(expression);
+		}
+
+		/**
+		 * Creates new {@link AggregationExpression} that compares two values and returns {@literal true} when the first
+		 * value is greater than the value of the referenced field.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public Gt greaterThan(String fieldReference) {
+			return createGt().greaterThan(fieldReference);
+		}
+
+		/**
+		 * Creates new {@link AggregationExpression} that compares two values and returns {@literal true} when the first
+		 * value is greater than the expression result.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public Gt greaterThan(AggregationExpression expression) {
+			return createGt().greaterThan(expression);
+		}
+
+		/**
+		 * Creates new {@link AggregationExpression} that compares two values and returns {@literal true} when the first
+		 * value is greater than the given value.
+		 *
+		 * @param value must not be {@literal null}.
+		 * @return
+		 */
+		public Gt greaterThanValue(Object value) {
+			return createGt().greaterThanValue(value);
+		}
+
+		private Gt createGt() {
+			return usesFieldRef() ? Gt.valueOf(fieldReference) : Gt.valueOf(expression);
+		}
+
+		/**
+		 * Creates new {@link AggregationExpression} that compares two values and returns {@literal true} when the first
+		 * value is greater than or equivalent to the value of the referenced field.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public Gte greaterThanEqualTo(String fieldReference) {
+			return createGte().greaterThanEqualTo(fieldReference);
+		}
+
+		/**
+		 * Creates new {@link AggregationExpression} that compares two values and returns {@literal true} when the first
+		 * value is greater than or equivalent to the expression result.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public Gte greaterThanEqualTo(AggregationExpression expression) {
+			return createGte().greaterThanEqualTo(expression);
+		}
+
+		/**
+		 * Creates new {@link AggregationExpression} that compares two values and returns {@literal true} when the first
+		 * value is greater than or equivalent to the given value.
+		 *
+		 * @param value must not be {@literal null}.
+		 * @return
+		 */
+		public Gte greaterThanEqualToValue(Object value) {
+			return createGte().greaterThanEqualToValue(value);
+		}
+
+		private Gte createGte() {
+			return usesFieldRef() ? Gte.valueOf(fieldReference) : Gte.valueOf(expression);
+		}
+
+		/**
+		 * Creates new {@link AggregationExpression} that compares two values and returns {@literal true} when the first
+		 * value is less than the value of the referenced field.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public Lt lessThan(String fieldReference) {
+			return createLt().lessThan(fieldReference);
+		}
+
+		/**
+		 * Creates new {@link AggregationExpression} that compares two values and returns {@literal true} when the first
+		 * value is less than the expression result.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public Lt lessThan(AggregationExpression expression) {
+			return createLt().lessThan(expression);
+		}
+
+		/**
+		 * Creates new {@link AggregationExpression} that compares two values and returns {@literal true} when the first
+		 * value is less than to the given value.
+		 *
+		 * @param value must not be {@literal null}.
+		 * @return
+		 */
+		public Lt lessThanValue(Object value) {
+			return createLt().lessThanValue(value);
+		}
+
+		private Lt createLt() {
+			return usesFieldRef() ? Lt.valueOf(fieldReference) : Lt.valueOf(expression);
+		}
+
+		/**
+		 * Creates new {@link AggregationExpression} that compares two values and returns {@literal true} when the first
+		 * value is less than or equivalent to the value of the referenced field.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public Lte lessThanEqualTo(String fieldReference) {
+			return createLte().lessThanEqualTo(fieldReference);
+		}
+
+		/**
+		 * Creates new {@link AggregationExpression} that compares two values and returns {@literal true} when the first
+		 * value is less than or equivalent to the expression result.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public Lte lessThanEqualTo(AggregationExpression expression) {
+			return createLte().lessThanEqualTo(expression);
+		}
+
+		/**
+		 * Creates new {@link AggregationExpression} that compares two values and returns {@literal true} when the first
+		 * value is less than or equivalent to the given value.
+		 *
+		 * @param value
+		 * @return
+		 */
+		public Lte lessThanEqualToValue(Object value) {
+			return createLte().lessThanEqualToValue(value);
+		}
+
+		private Lte createLte() {
+			return usesFieldRef() ? Lte.valueOf(fieldReference) : Lte.valueOf(expression);
+		}
+
+		/**
+		 * Creates new {@link AggregationExpression} that compares two values and returns {@literal true} when the values
+		 * are not equivalent.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public Ne notEqualTo(String fieldReference) {
+			return createNe().notEqualTo(fieldReference);
+		}
+
+		/**
+		 * Creates new {@link AggregationExpression} that compares two values and returns {@literal true} when the values
+		 * are not equivalent.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public Ne notEqualTo(AggregationExpression expression) {
+			return createNe().notEqualTo(expression);
+		}
+
+		/**
+		 * Creates new {@link AggregationExpression} that compares two values and returns {@literal true} when the values
+		 * are not equivalent.
+		 *
+		 * @param value must not be {@literal null}.
+		 * @return
+		 */
+		public Ne notEqualToValue(Object value) {
+			return createNe().notEqualToValue(value);
+		}
+
+		private Ne createNe() {
+			return usesFieldRef() ? Ne.valueOf(fieldReference) : Ne.valueOf(expression);
+		}
+
+		private boolean usesFieldRef() {
+			return fieldReference != null;
+		}
+	}
+
+	/**
+	 * {@link AggregationExpression} for {@code $cmp}.
+	 *
+	 * @author Christoph Strobl
+	 */
+	public static class Cmp extends AbstractAggregationExpression {
+
+		private Cmp(List<?> value) {
+			super(value);
+		}
+
+		@Override
+		protected String getMongoMethod() {
+			return "$cmp";
+		}
+
+		/**
+		 * Creates new {@link Cmp}.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public static Cmp valueOf(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			return new Cmp(asFields(fieldReference));
+		}
+
+		/**
+		 * Creates new {@link Cmp}.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public static Cmp valueOf(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return new Cmp(Collections.singletonList(expression));
+		}
+
+		/**
+		 * Creates new {@link Cmp} with all previously added arguments appending the given one.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public Cmp compareTo(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			return new Cmp(append(Fields.field(fieldReference)));
+		}
+
+		/**
+		 * Creates new {@link Cmp} with all previously added arguments appending the given one.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public Cmp compareTo(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return new Cmp(append(expression));
+		}
+
+		/**
+		 * Creates new {@link Cmp} with all previously added arguments appending the given one.
+		 *
+		 * @param value must not be {@literal null}.
+		 * @return
+		 */
+		public Cmp compareToValue(Object value) {
+
+			Assert.notNull(value, "Value must not be null!");
+			return new Cmp(append(value));
+		}
+	}
+
+	/**
+	 * {@link AggregationExpression} for {@code $eq}.
+	 *
+	 * @author Christoph Strobl
+	 */
+	public static class Eq extends AbstractAggregationExpression {
+
+		private Eq(List<?> value) {
+			super(value);
+		}
+
+		@Override
+		protected String getMongoMethod() {
+			return "$eq";
+		}
+
+		/**
+		 * Creates new {@link Eq}.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public static Eq valueOf(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			return new Eq(asFields(fieldReference));
+		}
+
+		/**
+		 * Creates new {@link Eq}.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public static Eq valueOf(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return new Eq(Collections.singletonList(expression));
+		}
+
+		/**
+		 * Creates new {@link Eq} with all previously added arguments appending the given one.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public Eq equalTo(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			return new Eq(append(Fields.field(fieldReference)));
+		}
+
+		/**
+		 * Creates new {@link Eq} with all previously added arguments appending the given one.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public Eq equalTo(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return new Eq(append(expression));
+		}
+
+		/**
+		 * Creates new {@link Eq} with all previously added arguments appending the given one.
+		 *
+		 * @param value must not be {@literal null}.
+		 * @return
+		 */
+		public Eq equalToValue(Object value) {
+
+			Assert.notNull(value, "Value must not be null!");
+			return new Eq(append(value));
+		}
+	}
+
+	/**
+	 * {@link AggregationExpression} for {@code $gt}.
+	 *
+	 * @author Christoph Strobl
+	 */
+	public static class Gt extends AbstractAggregationExpression {
+
+		private Gt(List<?> value) {
+			super(value);
+		}
+
+		@Override
+		protected String getMongoMethod() {
+			return "$gt";
+		}
+
+		/**
+		 * Creates new {@link Gt}.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public static Gt valueOf(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			return new Gt(asFields(fieldReference));
+		}
+
+		/**
+		 * Creates new {@link Gt}.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public static Gt valueOf(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return new Gt(Collections.singletonList(expression));
+		}
+
+		/**
+		 * Creates new {@link Gt} with all previously added arguments appending the given one.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public Gt greaterThan(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			return new Gt(append(Fields.field(fieldReference)));
+		}
+
+		/**
+		 * Creates new {@link Gt} with all previously added arguments appending the given one.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public Gt greaterThan(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return new Gt(append(expression));
+		}
+
+		/**
+		 * Creates new {@link Gt} with all previously added arguments appending the given one.
+		 *
+		 * @param value must not be {@literal null}.
+		 * @return
+		 */
+		public Gt greaterThanValue(Object value) {
+
+			Assert.notNull(value, "Value must not be null!");
+			return new Gt(append(value));
+		}
+	}
+
+	/**
+	 * {@link AggregationExpression} for {@code $lt}.
+	 *
+	 * @author Christoph Strobl
+	 */
+	public static class Lt extends AbstractAggregationExpression {
+
+		private Lt(List<?> value) {
+			super(value);
+		}
+
+		@Override
+		protected String getMongoMethod() {
+			return "$lt";
+		}
+
+		/**
+		 * Creates new {@link Lt}.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public static Lt valueOf(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			return new Lt(asFields(fieldReference));
+		}
+
+		/**
+		 * Creates new {@link Lt}.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public static Lt valueOf(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return new Lt(Collections.singletonList(expression));
+		}
+
+		/**
+		 * Creates new {@link Lt} with all previously added arguments appending the given one.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public Lt lessThan(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			return new Lt(append(Fields.field(fieldReference)));
+		}
+
+		/**
+		 * Creates new {@link Lt} with all previously added arguments appending the given one.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public Lt lessThan(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return new Lt(append(expression));
+		}
+
+		/**
+		 * Creates new {@link Lt} with all previously added arguments appending the given one.
+		 *
+		 * @param value must not be {@literal null}.
+		 * @return
+		 */
+		public Lt lessThanValue(Object value) {
+
+			Assert.notNull(value, "Value must not be null!");
+			return new Lt(append(value));
+		}
+	}
+
+	/**
+	 * {@link AggregationExpression} for {@code $gte}.
+	 *
+	 * @author Christoph Strobl
+	 */
+	public static class Gte extends AbstractAggregationExpression {
+
+		private Gte(List<?> value) {
+			super(value);
+		}
+
+		@Override
+		protected String getMongoMethod() {
+			return "$gte";
+		}
+
+		/**
+		 * Creates new {@link Gte}.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public static Gte valueOf(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			return new Gte(asFields(fieldReference));
+		}
+
+		/**
+		 * Creates new {@link Gte}.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public static Gte valueOf(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return new Gte(Collections.singletonList(expression));
+		}
+
+		/**
+		 * Creates new {@link Gte} with all previously added arguments appending the given one.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public Gte greaterThanEqualTo(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			return new Gte(append(Fields.field(fieldReference)));
+		}
+
+		/**
+		 * Creates new {@link Gte} with all previously added arguments appending the given one.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public Gte greaterThanEqualTo(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return new Gte(append(expression));
+		}
+
+		/**
+		 * Creates new {@link Gte} with all previously added arguments appending the given one.
+		 *
+		 * @param value must not be {@literal null}.
+		 * @return
+		 */
+		public Gte greaterThanEqualToValue(Object value) {
+
+			Assert.notNull(value, "Value must not be null!");
+			return new Gte(append(value));
+		}
+	}
+
+	/**
+	 * {@link AggregationExpression} for {@code $lte}.
+	 *
+	 * @author Christoph Strobl
+	 */
+	public static class Lte extends AbstractAggregationExpression {
+
+		private Lte(List<?> value) {
+			super(value);
+		}
+
+		@Override
+		protected String getMongoMethod() {
+			return "$lte";
+		}
+
+		/**
+		 * Creates new {@link Lte}.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public static Lte valueOf(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			return new Lte(asFields(fieldReference));
+		}
+
+		/**
+		 * Creates new {@link Lte}.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public static Lte valueOf(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return new Lte(Collections.singletonList(expression));
+		}
+
+		/**
+		 * Creates new {@link Lte} with all previously added arguments appending the given one.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public Lte lessThanEqualTo(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			return new Lte(append(Fields.field(fieldReference)));
+		}
+
+		/**
+		 * Creates new {@link Lte} with all previously added arguments appending the given one.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public Lte lessThanEqualTo(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return new Lte(append(expression));
+		}
+
+		/**
+		 * Creates new {@link Lte} with all previously added arguments appending the given one.
+		 *
+		 * @param value must not be {@literal null}.
+		 * @return
+		 */
+		public Lte lessThanEqualToValue(Object value) {
+
+			Assert.notNull(value, "Value must not be null!");
+			return new Lte(append(value));
+		}
+	}
+
+	/**
+	 * {@link AggregationExpression} for {@code $ne}.
+	 *
+	 * @author Christoph Strobl
+	 */
+	public static class Ne extends AbstractAggregationExpression {
+
+		private Ne(List<?> value) {
+			super(value);
+		}
+
+		@Override
+		protected String getMongoMethod() {
+			return "$ne";
+		}
+
+		/**
+		 * Creates new {@link Ne}.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public static Ne valueOf(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			return new Ne(asFields(fieldReference));
+		}
+
+		/**
+		 * Creates new {@link Ne}.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public static Ne valueOf(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return new Ne(Collections.singletonList(expression));
+		}
+
+		/**
+		 * Creates new {@link Ne} with all previously added arguments appending the given one.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public Ne notEqualTo(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			return new Ne(append(Fields.field(fieldReference)));
+		}
+
+		/**
+		 * Creates new {@link Ne} with all previously added arguments appending the given one.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public Ne notEqualTo(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return new Ne(append(expression));
+		}
+
+		/**
+		 * Creates new {@link Eq} with all previously added arguments appending the given one.
+		 *
+		 * @param value must not be {@literal null}.
+		 * @return
+		 */
+		public Ne notEqualToValue(Object value) {
+
+			Assert.notNull(value, "Value must not be null!");
+			return new Ne(append(value));
+		}
+	}
+}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/ConditionalOperator.java

@@ -1,392 +0,0 @@
-/*
- * Copyright 2016 the original author or authors.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-package org.springframework.data.mongodb.core.aggregation;
-
-import java.util.ArrayList;
-import java.util.List;
-
-import org.bson.Document;
-import org.springframework.dao.InvalidDataAccessApiUsageException;
-import org.springframework.data.mongodb.core.query.CriteriaDefinition;
-import org.springframework.util.Assert;
-import org.springframework.util.ClassUtils;
-
-/**
- * Encapsulates the aggregation framework {@code $cond} operator. A {@link ConditionalOperator} allows nested conditions
- * {@code if-then[if-then-else]-else} using {@link Field}, {@link CriteriaDefinition} or a {@link Document custom}
- * condition. Replacement values can be either {@link Field field references}, values of simple MongoDB types or values
- * that can be converted to a simple MongoDB type.
- * 
- * @see http://docs.mongodb.com/manual/reference/operator/aggregation/cond/
- * @author Mark Paluch
- * @author Christoph Strobl
- * @since 1.10
- */
-public class ConditionalOperator implements AggregationExpression {
-
-	private final Object condition;
-	private final Object thenValue;
-	private final Object otherwiseValue;
-
-	/**
-	 * Creates a new {@link ConditionalOperator} for a given {@link Field} and {@code then}/{@code otherwise} values.
-	 *
-	 * @param condition must not be {@literal null}.
-	 * @param thenValue must not be {@literal null}.
-	 * @param otherwiseValue must not be {@literal null}.
-	 */
-	public ConditionalOperator(Field condition, Object thenValue, Object otherwiseValue) {
-		this((Object) condition, thenValue, otherwiseValue);
-	}
-
-	/**
-	 * Creates a new {@link ConditionalOperator} for a given {@link CriteriaDefinition} and {@code then}/{@code otherwise}
-	 * values.
-	 *
-	 * @param condition must not be {@literal null}.
-	 * @param thenValue must not be {@literal null}.
-	 * @param otherwiseValue must not be {@literal null}.
-	 */
-	public ConditionalOperator(CriteriaDefinition condition, Object thenValue, Object otherwiseValue) {
-		this((Object) condition, thenValue, otherwiseValue);
-	}
-
-	/**
-	 * Creates a new {@link ConditionalOperator} for a given {@link Document criteria} and {@code then}/{@code otherwise}
-	 * values.
-	 *
-	 * @param condition must not be {@literal null}.
-	 * @param thenValue must not be {@literal null}.
-	 * @param otherwiseValue must not be {@literal null}.
-	 */
-	public ConditionalOperator(Document condition, Object thenValue, Object otherwiseValue) {
-		this((Object) condition, thenValue, otherwiseValue);
-	}
-
-	private ConditionalOperator(Object condition, Object thenValue, Object otherwiseValue) {
-
-		Assert.notNull(condition, "Condition must not be null!");
-		Assert.notNull(thenValue, "'Then value' must not be null!");
-		Assert.notNull(otherwiseValue, "'Otherwise value' must not be null!");
-
-		assertNotBuilder(condition, "Condition");
-		assertNotBuilder(thenValue, "'Then value'");
-		assertNotBuilder(otherwiseValue, "'Otherwise value'");
-
-		this.condition = condition;
-		this.thenValue = thenValue;
-		this.otherwiseValue = otherwiseValue;
-	}
-
-	/* 
-	 * (non-Javadoc)
-	 * @see org.springframework.data.mongodb.core.aggregation.AggregationExpression#toDocument(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
-	 */
-	@Override
-	public Document toDocument(AggregationOperationContext context) {
-
-		Document condObject = new Document();
-
-		condObject.append("if", resolveCriteria(context, condition));
-		condObject.append("then", resolveValue(context, thenValue));
-		condObject.append("else", resolveValue(context, otherwiseValue));
-
-		return new Document("$cond", condObject);
-	}
-
-	private Object resolveValue(AggregationOperationContext context, Object value) {
-
-		if (value instanceof Document || value instanceof Field) {
-			return resolve(context, value);
-		}
-
-		if (value instanceof ConditionalOperator) {
-			return ((ConditionalOperator) value).toDocument(context);
-		}
-
-		return context.getMappedObject(new Document("$set", value)).get("$set");
-	}
-
-	private Object resolveCriteria(AggregationOperationContext context, Object value) {
-
-		if (value instanceof Document || value instanceof Field) {
-			return resolve(context, value);
-		}
-
-		if (value instanceof CriteriaDefinition) {
-
-			Document mappedObject = context.getMappedObject(((CriteriaDefinition) value).getCriteriaObject());
-			List<Object> clauses = new ArrayList<Object>();
-
-			clauses.addAll(getClauses(context, mappedObject));
-
-			if (clauses.size() == 1) {
-				return clauses.get(0);
-			}
-
-			return clauses;
-		}
-
-		throw new InvalidDataAccessApiUsageException(
-				String.format("Invalid value in condition. Supported: Document, Field references, Criteria, got: %s", value));
-	}
-
-	private List<Object> getClauses(AggregationOperationContext context, Document mappedObject) {
-
-		List<Object> clauses = new ArrayList<Object>();
-
-		for (String key : mappedObject.keySet()) {
-
-			Object predicate = mappedObject.get(key);
-			clauses.addAll(getClauses(context, key, predicate));
-		}
-
-		return clauses;
-	}
-
-	private List<Object> getClauses(AggregationOperationContext context, String key, Object predicate) {
-
-		List<Object> clauses = new ArrayList<Object>();
-
-		if (predicate instanceof List) {
-
-			List<Object> args = new ArrayList<Object>();
-			for (Object clause : (List<?>) predicate) {
-				if (clause instanceof Document) {
-					args.addAll(getClauses(context, (Document) clause));
-				}
-			}
-
-			clauses.add(new Document(key, args));
-
-		} else if (predicate instanceof Document) {
-
-			Document nested = (Document) predicate;
-
-			for (String s : nested.keySet()) {
-
-				if (!isKeyword(s)) {
-					continue;
-				}
-
-				List<Object> args = new ArrayList<Object>();
-				args.add("$" + key);
-				args.add(nested.get(s));
-				clauses.add(new Document(s, args));
-			}
-
-		} else if (!isKeyword(key)) {
-
-			List<Object> args = new ArrayList<Object>();
-			args.add("$" + key);
-			args.add(predicate);
-			clauses.add(new Document("$eq", args));
-		}
-
-		return clauses;
-	}
-
-	/**
-	 * Returns whether the given {@link String} is a MongoDB keyword.
-	 *
-	 * @param candidate
-	 * @return
-	 */
-	private boolean isKeyword(String candidate) {
-		return candidate.startsWith("$");
-	}
-
-	private Object resolve(AggregationOperationContext context, Object value) {
-
-		if (value instanceof Document) {
-			return context.getMappedObject((Document) value);
-		}
-
-		return context.getReference((Field) value).toString();
-	}
-
-	private void assertNotBuilder(Object toCheck, String name) {
-		Assert.isTrue(!ClassUtils.isAssignableValue(ConditionalExpressionBuilder.class, toCheck),
-				String.format("%s must not be of type %s", name, ConditionalExpressionBuilder.class.getSimpleName()));
-	}
-
-	/**
-	 * Get a builder that allows fluent creation of {@link ConditionalOperator}.
-	 *
-	 * @return a new {@link ConditionalExpressionBuilder}.
-	 */
-	public static ConditionalExpressionBuilder newBuilder() {
-		return ConditionalExpressionBuilder.newBuilder();
-	}
-
-	/**
-	 * @since 1.10
-	 */
-	public static interface WhenBuilder {
-
-		/**
-		 * @param booleanExpression expression that yields in a boolean result, must not be {@literal null}.
-		 * @return the {@link ThenBuilder}
-		 */
-		ThenBuilder when(Document booleanExpression);
-
-		/**
-		 * @param booleanField reference to a field holding a boolean value, must not be {@literal null}.
-		 * @return the {@link ThenBuilder}
-		 */
-		ThenBuilder when(Field booleanField);
-
-		/**
-		 * @param booleanField name of a field holding a boolean value, must not be {@literal null}.
-		 * @return the {@link ThenBuilder}
-		 */
-		ThenBuilder when(String booleanField);
-
-		/**
-		 * @param criteria criteria to evaluate, must not be {@literal null}.
-		 * @return the {@link ThenBuilder}
-		 */
-		ThenBuilder when(CriteriaDefinition criteria);
-	}
-
-	/**
-	 * @since 1.10
-	 */
-	public static interface ThenBuilder {
-
-		/**
-		 * @param value the value to be used if the condition evaluates {@literal true}. Can be a {@link Document}, a value
-		 *          that is supported by MongoDB or a value that can be converted to a MongoDB representation but must not
-		 *          be {@literal null}.
-		 * @return the {@link OtherwiseBuilder}
-		 */
-		OtherwiseBuilder then(Object value);
-	}
-
-	/**
-	 * @since 1.10
-	 */
-	public static interface OtherwiseBuilder {
-
-		/**
-		 * @param value the value to be used if the condition evaluates {@literal false}. Can be a {@link Document}, a value
-		 *          that is supported by MongoDB or a value that can be converted to a MongoDB representation but must not
-		 *          be {@literal null}.
-		 * @return the {@link ConditionalOperator}
-		 */
-		ConditionalOperator otherwise(Object value);
-	}
-
-	/**
-	 * Builder for fluent {@link ConditionalOperator} creation.
-	 *
-	 * @author Mark Paluch
-	 * @since 1.10
-	 */
-	public static final class ConditionalExpressionBuilder implements WhenBuilder, ThenBuilder, OtherwiseBuilder {
-
-		private Object condition;
-		private Object thenValue;
-
-		private ConditionalExpressionBuilder() {}
-
-		/**
-		 * Creates a new builder for {@link ConditionalOperator}.
-		 *
-		 * @return never {@literal null}.
-		 */
-		public static ConditionalExpressionBuilder newBuilder() {
-			return new ConditionalExpressionBuilder();
-		}
-
-		/* 
-		 * (non-Javadoc)
-		 * @see org.springframework.data.mongodb.core.aggregation.ConditionalOperator.WhenBuilder#when(org.bson.Document)
-		 */
-		@Override
-		public ConditionalExpressionBuilder when(Document booleanExpression) {
-
-			Assert.notNull(booleanExpression, "'Boolean expression' must not be null!");
-
-			this.condition = booleanExpression;
-			return this;
-		}
-
-		/*
-		 * (non-Javadoc)
-		 * @see org.springframework.data.mongodb.core.aggregation.ConditionalOperator.WhenBuilder#when(org.springframework.data.mongodb.core.query.CriteriaDefinition)
-		 */
-		@Override
-		public ThenBuilder when(CriteriaDefinition criteria) {
-
-			Assert.notNull(criteria, "Criteria must not be null!");
-
-			this.condition = criteria;
-			return this;
-		}
-
-		/*
-		 * (non-Javadoc)
-		 * @see org.springframework.data.mongodb.core.aggregation.ConditionalOperator.WhenBuilder#when(org.springframework.data.mongodb.core.aggregation.Field)
-		 */
-		@Override
-		public ThenBuilder when(Field booleanField) {
-
-			Assert.notNull(booleanField, "Boolean field must not be null!");
-
-			this.condition = booleanField;
-			return this;
-		}
-
-		/*
-		 * (non-Javadoc)
-		 * @see org.springframework.data.mongodb.core.aggregation.ConditionalOperator.WhenBuilder#when(java.lang.String)
-		 */
-		@Override
-		public ThenBuilder when(String booleanField) {
-
-			Assert.hasText(booleanField, "Boolean field name must not be null or empty!");
-
-			this.condition = Fields.field(booleanField);
-			return this;
-		}
-
-		/*
-		 * (non-Javadoc)
-		 * @see org.springframework.data.mongodb.core.aggregation.ConditionalOperator.ThenBuilder#then(java.lang.Object)
-		 */
-		@Override
-		public OtherwiseBuilder then(Object thenValue) {
-
-			Assert.notNull(thenValue, "'Then-value' must not be null!");
-
-			this.thenValue = thenValue;
-			return this;
-		}
-
-		/*
-		 * (non-Javadoc)
-		 * @see org.springframework.data.mongodb.core.aggregation.ConditionalOperator.OtherwiseBuilder#otherwise(java.lang.Object)
-		 */
-		@Override
-		public ConditionalOperator otherwise(Object otherwiseValue) {
-
-			Assert.notNull(otherwiseValue, "'Otherwise-value' must not be null!");
-
-			return new ConditionalOperator(condition, thenValue, otherwiseValue);
-		}
-	}
-}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/ConditionalOperators.java

@@ -0,0 +1,978 @@
+/*
+ * Copyright 2016. the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb.core.aggregation;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+
+import org.springframework.dao.InvalidDataAccessApiUsageException;
+import org.springframework.data.mongodb.core.aggregation.ConditionalOperators.Cond.OtherwiseBuilder;
+import org.springframework.data.mongodb.core.aggregation.ConditionalOperators.Cond.ThenBuilder;
+import org.springframework.data.mongodb.core.aggregation.ConditionalOperators.Switch.CaseOperator;
+import org.springframework.data.mongodb.core.query.CriteriaDefinition;
+import org.springframework.util.Assert;
+import org.springframework.util.ClassUtils;
+
+import com.mongodb.BasicDBObject;
+import com.mongodb.DBObject;
+
+/**
+ * Gateway to {@literal conditional expressions} that evaluate their argument expressions as booleans to a value.
+ *
+ * @author Mark Paluch
+ * @since 1.10
+ */
+public class ConditionalOperators {
+
+	/**
+	 * Take the field referenced by given {@literal fieldReference}.
+	 *
+	 * @param fieldReference must not be {@literal null}.
+	 * @return
+	 */
+	public static ConditionalOperatorFactory when(String fieldReference) {
+		return new ConditionalOperatorFactory(fieldReference);
+	}
+
+	/**
+	 * Take the value resulting from the given {@literal expression}.
+	 *
+	 * @param expression must not be {@literal null}.
+	 * @return
+	 */
+	public static ConditionalOperatorFactory when(AggregationExpression expression) {
+		return new ConditionalOperatorFactory(expression);
+	}
+
+	/**
+	 * Take the value resulting from the given {@literal criteriaDefinition}.
+	 *
+	 * @param criteriaDefinition must not be {@literal null}.
+	 * @return
+	 */
+	public static ConditionalOperatorFactory when(CriteriaDefinition criteriaDefinition) {
+		return new ConditionalOperatorFactory(criteriaDefinition);
+	}
+
+	/**
+	 * Creates new {@link AggregationExpression} that evaluates an expression and returns the value of the expression if
+	 * the expression evaluates to a non-null value. If the expression evaluates to a {@literal null} value, including
+	 * instances of undefined values or missing fields, returns the value of the replacement expression.
+	 *
+	 * @param fieldReference must not be {@literal null}.
+	 * @return
+	 */
+	public static IfNull.ThenBuilder ifNull(String fieldReference) {
+
+		Assert.notNull(fieldReference, "FieldReference must not be null!");
+		return IfNull.ifNull(fieldReference);
+	}
+
+	/**
+	 * Creates new {@link AggregationExpression} that evaluates an expression and returns the value of the expression if
+	 * the expression evaluates to a non-null value. If the expression evaluates to a {@literal null} value, including
+	 * instances of undefined values or missing fields, returns the value of the replacement expression.
+	 *
+	 * @param expression must not be {@literal null}.
+	 * @return
+	 */
+	public static IfNull.ThenBuilder ifNull(AggregationExpression expression) {
+
+		Assert.notNull(expression, "Expression must not be null!");
+		return IfNull.ifNull(expression);
+	}
+
+	/**
+	 * Creates new {@link AggregationExpression} that evaluates a series of {@link CaseOperator} expressions. When it
+	 * finds an expression which evaluates to {@literal true}, {@code $switch} executes a specified expression and breaks
+	 * out of the control flow.
+	 *
+	 * @param conditions must not be {@literal null}.
+	 * @return
+	 */
+	public static Switch switchCases(CaseOperator... conditions) {
+		return Switch.switchCases(conditions);
+	}
+
+	/**
+	 * Creates new {@link AggregationExpression} that evaluates a series of {@link CaseOperator} expressions. When it
+	 * finds an expression which evaluates to {@literal true}, {@code $switch} executes a specified expression and breaks
+	 * out of the control flow.
+	 *
+	 * @param conditions must not be {@literal null}.
+	 * @return
+	 */
+	public static Switch switchCases(List<CaseOperator> conditions) {
+		return Switch.switchCases(conditions);
+	}
+
+	public static class ConditionalOperatorFactory {
+
+		private final String fieldReference;
+		private final AggregationExpression expression;
+		private final CriteriaDefinition criteriaDefinition;
+
+		/**
+		 * Creates new {@link ConditionalOperatorFactory} for given {@literal fieldReference}.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 */
+		public ConditionalOperatorFactory(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+
+			this.fieldReference = fieldReference;
+			this.expression = null;
+			this.criteriaDefinition = null;
+		}
+
+		/**
+		 * Creates new {@link ConditionalOperatorFactory} for given {@link AggregationExpression}.
+		 *
+		 * @param expression must not be {@literal null}.
+		 */
+		public ConditionalOperatorFactory(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+
+			this.fieldReference = null;
+			this.expression = expression;
+			this.criteriaDefinition = null;
+		}
+
+		/**
+		 * Creates new {@link ConditionalOperatorFactory} for given {@link CriteriaDefinition}.
+		 *
+		 * @param criteriaDefinition must not be {@literal null}.
+		 */
+		public ConditionalOperatorFactory(CriteriaDefinition criteriaDefinition) {
+
+			Assert.notNull(criteriaDefinition, "CriteriaDefinition must not be null!");
+
+			this.fieldReference = null;
+			this.expression = null;
+			this.criteriaDefinition = criteriaDefinition;
+		}
+
+		/**
+		 * Creates new {@link AggregationExpression} that evaluates a boolean expression to return one of the two specified
+		 * return expressions.
+		 *
+		 * @param value must not be {@literal null}.
+		 * @return
+		 */
+		public OtherwiseBuilder then(Object value) {
+
+			Assert.notNull(value, "Value must not be null!");
+			return createThenBuilder().then(value);
+		}
+
+		/**
+		 * Creates new {@link AggregationExpression} that evaluates a boolean expression to return one of the two specified
+		 * return expressions.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public OtherwiseBuilder thenValueOf(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return createThenBuilder().then(expression);
+		}
+
+		/**
+		 * Creates new {@link AggregationExpression} that evaluates a boolean expression to return one of the two specified
+		 * return expressions.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public OtherwiseBuilder thenValueOf(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			return createThenBuilder().then(fieldReference);
+		}
+
+		private ThenBuilder createThenBuilder() {
+
+			if (usesFieldRef()) {
+				return Cond.newBuilder().when(fieldReference);
+			}
+
+			return usesCriteriaDefinition() ? Cond.newBuilder().when(criteriaDefinition) : Cond.newBuilder().when(expression);
+		}
+
+		private boolean usesFieldRef() {
+			return this.fieldReference != null;
+		}
+
+		private boolean usesCriteriaDefinition() {
+			return this.criteriaDefinition != null;
+		}
+	}
+
+	/**
+	 * Encapsulates the aggregation framework {@code $ifNull} operator. Replacement values can be either {@link Field
+	 * field references}, {@link AggregationExpression expressions}, values of simple MongoDB types or values that can be
+	 * converted to a simple MongoDB type.
+	 *
+	 * @see <a href=
+	 *      "https://docs.mongodb.com/manual/reference/operator/aggregation/ifNull/">https://docs.mongodb.com/manual/reference/operator/aggregation/ifNull/</a>
+	 * @author Mark Paluch
+	 */
+	public static class IfNull implements AggregationExpression {
+
+		private final Object condition;
+		private final Object value;
+
+		private IfNull(Object condition, Object value) {
+
+			this.condition = condition;
+			this.value = value;
+		}
+
+		/**
+		 * Creates new {@link IfNull}.
+		 *
+		 * @param fieldReference the field to check for a {@literal null} value, field reference must not be {@literal null}
+		 *          .
+		 * @return
+		 */
+		public static ThenBuilder ifNull(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			return new IfNullOperatorBuilder().ifNull(fieldReference);
+		}
+
+		/**
+		 * Creates new {@link IfNull}.
+		 *
+		 * @param expression the expression to check for a {@literal null} value, field reference must not be
+		 *          {@literal null}.
+		 * @return
+		 */
+		public static ThenBuilder ifNull(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return new IfNullOperatorBuilder().ifNull(expression);
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.AggregationExpression#toDbObject(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
+		 */
+		@Override
+		public DBObject toDbObject(AggregationOperationContext context) {
+
+			List<Object> list = new ArrayList<Object>();
+
+			if (condition instanceof Field) {
+				list.add(context.getReference((Field) condition).toString());
+			} else if (condition instanceof AggregationExpression) {
+				list.add(((AggregationExpression) condition).toDbObject(context));
+			} else {
+				list.add(condition);
+			}
+
+			list.add(resolve(value, context));
+
+			return new BasicDBObject("$ifNull", list);
+		}
+
+		private Object resolve(Object value, AggregationOperationContext context) {
+
+			if (value instanceof Field) {
+				return context.getReference((Field) value).toString();
+			} else if (value instanceof AggregationExpression) {
+				return ((AggregationExpression) value).toDbObject(context);
+			} else if (value instanceof DBObject) {
+				return value;
+			}
+
+			return context.getMappedObject(new BasicDBObject("$set", value)).get("$set");
+		}
+
+		/**
+		 * @author Mark Paluch
+		 */
+		public interface IfNullBuilder {
+
+			/**
+			 * @param fieldReference the field to check for a {@literal null} value, field reference must not be
+			 *          {@literal null}.
+			 * @return the {@link ThenBuilder}
+			 */
+			ThenBuilder ifNull(String fieldReference);
+
+			/**
+			 * @param expression the expression to check for a {@literal null} value, field name must not be {@literal null}
+			 *          or empty.
+			 * @return the {@link ThenBuilder}
+			 */
+			ThenBuilder ifNull(AggregationExpression expression);
+		}
+
+		/**
+		 * @author Mark Paluch
+		 */
+		public interface ThenBuilder {
+
+			/**
+			 * @param value the value to be used if the {@code $ifNull} condition evaluates {@literal true}. Can be a
+			 *          {@link DBObject}, a value that is supported by MongoDB or a value that can be converted to a MongoDB
+			 *          representation but must not be {@literal null}.
+			 * @return
+			 */
+			IfNull then(Object value);
+
+			/**
+			 * @param fieldReference the field holding the replacement value, must not be {@literal null}.
+			 * @return
+			 */
+			IfNull thenValueOf(String fieldReference);
+
+			/**
+			 * @param expression the expression yielding to the replacement value, must not be {@literal null}.
+			 * @return
+			 */
+			IfNull thenValueOf(AggregationExpression expression);
+		}
+
+		/**
+		 * Builder for fluent {@link IfNull} creation.
+		 *
+		 * @author Mark Paluch
+		 */
+		static final class IfNullOperatorBuilder implements IfNullBuilder, ThenBuilder {
+
+			private Object condition;
+
+			private IfNullOperatorBuilder() {}
+
+			/**
+			 * Creates a new builder for {@link IfNull}.
+			 *
+			 * @return never {@literal null}.
+			 */
+			public static IfNullOperatorBuilder newBuilder() {
+				return new IfNullOperatorBuilder();
+			}
+
+			/* (non-Javadoc)
+			 * @see org.springframework.data.mongodb.core.aggregation.ConditionalOperators.IfNull.IfNullBuilder#ifNull(java.lang.String)
+			 */
+			public ThenBuilder ifNull(String fieldReference) {
+
+				Assert.hasText(fieldReference, "FieldReference name must not be null or empty!");
+				this.condition = Fields.field(fieldReference);
+				return this;
+			}
+
+			/* (non-Javadoc)
+			 * @see org.springframework.data.mongodb.core.aggregation.ConditionalOperators.IfNull.IfNullBuilder#ifNull(org.springframework.data.mongodb.core.aggregation.AggregationExpression)
+			 */
+			@Override
+			public ThenBuilder ifNull(AggregationExpression expression) {
+
+				Assert.notNull(expression, "AggregationExpression name must not be null or empty!");
+				this.condition = expression;
+				return this;
+			}
+
+			/* (non-Javadoc)
+			 * @see org.springframework.data.mongodb.core.aggregation.ConditionalOperators.IfNull.ThenBuilder#then(java.lang.Object)
+			 */
+			public IfNull then(Object value) {
+				return new IfNull(condition, value);
+			}
+
+			/* (non-Javadoc)
+			 * @see org.springframework.data.mongodb.core.aggregation.ConditionalOperators.IfNull.ThenBuilder#thenValueOf(java.lang.String)
+			 */
+			public IfNull thenValueOf(String fieldReference) {
+
+				Assert.notNull(fieldReference, "FieldReference must not be null!");
+				return new IfNull(condition, Fields.field(fieldReference));
+			}
+
+			/* (non-Javadoc)
+			 * @see org.springframework.data.mongodb.core.aggregation.ConditionalOperators.IfNull.ThenBuilder#thenValueOf(org.springframework.data.mongodb.core.aggregation.AggregationExpression)
+			 */
+			public IfNull thenValueOf(AggregationExpression expression) {
+
+				Assert.notNull(expression, "Expression must not be null!");
+				return new IfNull(condition, expression);
+			}
+		}
+	}
+
+	/**
+	 * {@link AggregationExpression} for {@code $switch}.
+	 *
+	 * @author Christoph Strobl
+	 */
+	public static class Switch extends AbstractAggregationExpression {
+
+		private Switch(java.util.Map<String, Object> values) {
+			super(values);
+		}
+
+		@Override
+		protected String getMongoMethod() {
+			return "$switch";
+		}
+
+		/**
+		 * Creates new {@link Switch}.
+		 *
+		 * @param conditions must not be {@literal null}.
+		 */
+		public static Switch switchCases(CaseOperator... conditions) {
+
+			Assert.notNull(conditions, "Conditions must not be null!");
+			return switchCases(Arrays.asList(conditions));
+		}
+
+		/**
+		 * Creates new {@link Switch}.
+		 *
+		 * @param conditions must not be {@literal null}.
+		 */
+		public static Switch switchCases(List<CaseOperator> conditions) {
+
+			Assert.notNull(conditions, "Conditions must not be null!");
+			return new Switch(Collections.<String, Object> singletonMap("branches", new ArrayList<CaseOperator>(conditions)));
+		}
+
+		public Switch defaultTo(Object value) {
+			return new Switch(append("default", value));
+		}
+
+		/**
+		 * Encapsulates the aggregation framework case document inside a {@code $switch}-operation.
+		 */
+		public static class CaseOperator implements AggregationExpression {
+
+			private final AggregationExpression when;
+			private final Object then;
+
+			private CaseOperator(AggregationExpression when, Object then) {
+
+				this.when = when;
+				this.then = then;
+			}
+
+			public static ThenBuilder when(final AggregationExpression condition) {
+
+				Assert.notNull(condition, "Condition must not be null!");
+
+				return new ThenBuilder() {
+
+					@Override
+					public CaseOperator then(Object value) {
+
+						Assert.notNull(value, "Value must not be null!");
+						return new CaseOperator(condition, value);
+					}
+				};
+			}
+
+			/* (non-Javadoc)
+			 * @see org.springframework.data.mongodb.core.aggregation.AggregationExpression#toDbObject(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
+			 */
+			@Override
+			public DBObject toDbObject(AggregationOperationContext context) {
+
+				DBObject dbo = new BasicDBObject("case", when.toDbObject(context));
+
+				if (then instanceof AggregationExpression) {
+					dbo.put("then", ((AggregationExpression) then).toDbObject(context));
+				} else if (then instanceof Field) {
+					dbo.put("then", context.getReference((Field) then).toString());
+				} else {
+					dbo.put("then", then);
+				}
+
+				return dbo;
+			}
+
+			/**
+			 * @author Christoph Strobl
+			 */
+			public interface ThenBuilder {
+
+				/**
+				 * Set the then {@literal value}.
+				 *
+				 * @param value must not be {@literal null}.
+				 * @return
+				 */
+				CaseOperator then(Object value);
+			}
+		}
+	}
+
+	/**
+	 * Encapsulates the aggregation framework {@code $cond} operator. A {@link Cond} allows nested conditions
+	 * {@code if-then[if-then-else]-else} using {@link Field}, {@link CriteriaDefinition}, {@link AggregationExpression}
+	 * or a {@link DBObject custom} condition. Replacement values can be either {@link Field field references},
+	 * {@link AggregationExpression expressions}, values of simple MongoDB types or values that can be converted to a
+	 * simple MongoDB type.
+	 *
+	 * @see <a href=
+	 *      "https://docs.mongodb.com/manual/reference/operator/aggregation/cond/">https://docs.mongodb.com/manual/reference/operator/aggregation/cond/</a>
+	 * @author Mark Paluch
+	 * @author Christoph Strobl
+	 */
+	public static class Cond implements AggregationExpression {
+
+		private final Object condition;
+		private final Object thenValue;
+		private final Object otherwiseValue;
+
+		/**
+		 * Creates a new {@link Cond} for a given {@link Field} and {@code then}/{@code otherwise} values.
+		 *
+		 * @param condition must not be {@literal null}.
+		 * @param thenValue must not be {@literal null}.
+		 * @param otherwiseValue must not be {@literal null}.
+		 */
+		private Cond(Field condition, Object thenValue, Object otherwiseValue) {
+			this((Object) condition, thenValue, otherwiseValue);
+		}
+
+		/**
+		 * Creates a new {@link Cond} for a given {@link CriteriaDefinition} and {@code then}/{@code otherwise} values.
+		 *
+		 * @param condition must not be {@literal null}.
+		 * @param thenValue must not be {@literal null}.
+		 * @param otherwiseValue must not be {@literal null}.
+		 */
+		private Cond(CriteriaDefinition condition, Object thenValue, Object otherwiseValue) {
+			this((Object) condition, thenValue, otherwiseValue);
+		}
+
+		private Cond(Object condition, Object thenValue, Object otherwiseValue) {
+
+			Assert.notNull(condition, "Condition must not be null!");
+			Assert.notNull(thenValue, "Then value must not be null!");
+			Assert.notNull(otherwiseValue, "Otherwise value must not be null!");
+
+			assertNotBuilder(condition, "Condition");
+			assertNotBuilder(thenValue, "Then value");
+			assertNotBuilder(otherwiseValue, "Otherwise value");
+
+			this.condition = condition;
+			this.thenValue = thenValue;
+			this.otherwiseValue = otherwiseValue;
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.AggregationExpression#toDbObject(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
+		 */
+		@Override
+		public DBObject toDbObject(AggregationOperationContext context) {
+
+			BasicDBObject condObject = new BasicDBObject();
+
+			condObject.append("if", resolveCriteria(context, condition));
+			condObject.append("then", resolveValue(context, thenValue));
+			condObject.append("else", resolveValue(context, otherwiseValue));
+
+			return new BasicDBObject("$cond", condObject);
+		}
+
+		private Object resolveValue(AggregationOperationContext context, Object value) {
+
+			if (value instanceof DBObject || value instanceof Field) {
+				return resolve(context, value);
+			}
+
+			if (value instanceof AggregationExpression) {
+				return ((AggregationExpression) value).toDbObject(context);
+			}
+
+			return context.getMappedObject(new BasicDBObject("$set", value)).get("$set");
+		}
+
+		private Object resolveCriteria(AggregationOperationContext context, Object value) {
+
+			if (value instanceof DBObject || value instanceof Field) {
+				return resolve(context, value);
+			}
+
+			if (value instanceof AggregationExpression) {
+				return ((AggregationExpression) value).toDbObject(context);
+			}
+
+			if (value instanceof CriteriaDefinition) {
+
+				DBObject mappedObject = context.getMappedObject(((CriteriaDefinition) value).getCriteriaObject());
+				List<Object> clauses = new ArrayList<Object>();
+
+				clauses.addAll(getClauses(context, mappedObject));
+
+				return clauses.size() == 1 ? clauses.get(0) : clauses;
+			}
+
+			throw new InvalidDataAccessApiUsageException(
+					String.format("Invalid value in condition. Supported: DBObject, Field references, Criteria, got: %s", value));
+		}
+
+		private List<Object> getClauses(AggregationOperationContext context, DBObject mappedObject) {
+
+			List<Object> clauses = new ArrayList<Object>();
+
+			for (String key : mappedObject.keySet()) {
+
+				Object predicate = mappedObject.get(key);
+				clauses.addAll(getClauses(context, key, predicate));
+			}
+
+			return clauses;
+		}
+
+		private List<Object> getClauses(AggregationOperationContext context, String key, Object predicate) {
+
+			List<Object> clauses = new ArrayList<Object>();
+
+			if (predicate instanceof List) {
+
+				List<Object> args = new ArrayList<Object>();
+				for (Object clause : (List<?>) predicate) {
+					if (clause instanceof DBObject) {
+						args.addAll(getClauses(context, (DBObject) clause));
+					}
+				}
+
+				clauses.add(new BasicDBObject(key, args));
+
+			} else if (predicate instanceof DBObject) {
+
+				DBObject nested = (DBObject) predicate;
+
+				for (String s : nested.keySet()) {
+
+					if (!isKeyword(s)) {
+						continue;
+					}
+
+					List<Object> args = new ArrayList<Object>();
+					args.add("$" + key);
+					args.add(nested.get(s));
+					clauses.add(new BasicDBObject(s, args));
+				}
+
+			} else if (!isKeyword(key)) {
+
+				List<Object> args = new ArrayList<Object>();
+				args.add("$" + key);
+				args.add(predicate);
+				clauses.add(new BasicDBObject("$eq", args));
+			}
+
+			return clauses;
+		}
+
+		/**
+		 * Returns whether the given {@link String} is a MongoDB keyword.
+		 *
+		 * @param candidate
+		 * @return
+		 */
+		private boolean isKeyword(String candidate) {
+			return candidate.startsWith("$");
+		}
+
+		private Object resolve(AggregationOperationContext context, Object value) {
+
+			if (value instanceof DBObject) {
+				return context.getMappedObject((DBObject) value);
+			}
+
+			return context.getReference((Field) value).toString();
+		}
+
+		private void assertNotBuilder(Object toCheck, String name) {
+			Assert.isTrue(!ClassUtils.isAssignableValue(ConditionalExpressionBuilder.class, toCheck),
+					String.format("%s must not be of type %s", name, ConditionalExpressionBuilder.class.getSimpleName()));
+		}
+
+		/**
+		 * Get a builder that allows fluent creation of {@link Cond}.
+		 *
+		 * @return never {@literal null}.
+		 */
+		public static WhenBuilder newBuilder() {
+			return ConditionalExpressionBuilder.newBuilder();
+		}
+
+		/**
+		 * Start creating new {@link Cond} by providing the boolean expression used in {@code if}.
+		 *
+		 * @param booleanExpression must not be {@literal null}.
+		 * @return never {@literal null}.
+		 */
+		public static ThenBuilder when(DBObject booleanExpression) {
+			return ConditionalExpressionBuilder.newBuilder().when(booleanExpression);
+		}
+
+		/**
+		 * Start creating new {@link Cond} by providing the {@link AggregationExpression} used in {@code if}.
+		 *
+		 * @param expression expression that yields in a boolean result, must not be {@literal null}.
+		 * @return never {@literal null}.
+		 */
+		public static ThenBuilder when(AggregationExpression expression) {
+			return ConditionalExpressionBuilder.newBuilder().when(expression);
+		}
+
+		/**
+		 * Start creating new {@link Cond} by providing the field reference used in {@code if}.
+		 *
+		 * @param booleanField name of a field holding a boolean value, must not be {@literal null}.
+		 * @return never {@literal null}.
+		 */
+		public static ThenBuilder when(String booleanField) {
+			return ConditionalExpressionBuilder.newBuilder().when(booleanField);
+		}
+
+		/**
+		 * Start creating new {@link Cond} by providing the {@link CriteriaDefinition} used in {@code if}.
+		 *
+		 * @param criteria criteria to evaluate, must not be {@literal null}.
+		 * @return the {@link ThenBuilder}
+		 */
+		public static ThenBuilder when(CriteriaDefinition criteria) {
+			return ConditionalExpressionBuilder.newBuilder().when(criteria);
+		}
+
+		/**
+		 * @author Mark Paluch
+		 */
+		public interface WhenBuilder {
+
+			/**
+			 * @param booleanExpression expression that yields in a boolean result, must not be {@literal null}.
+			 * @return the {@link ThenBuilder}
+			 */
+			ThenBuilder when(DBObject booleanExpression);
+
+			/**
+			 * @param expression expression that yields in a boolean result, must not be {@literal null}.
+			 * @return the {@link ThenBuilder}
+			 */
+			ThenBuilder when(AggregationExpression expression);
+
+			/**
+			 * @param booleanField name of a field holding a boolean value, must not be {@literal null}.
+			 * @return the {@link ThenBuilder}
+			 */
+			ThenBuilder when(String booleanField);
+
+			/**
+			 * @param criteria criteria to evaluate, must not be {@literal null}.
+			 * @return the {@link ThenBuilder}
+			 */
+			ThenBuilder when(CriteriaDefinition criteria);
+		}
+
+		/**
+		 * @author Mark Paluch
+		 */
+		public interface ThenBuilder {
+
+			/**
+			 * @param value the value to be used if the condition evaluates {@literal true}. Can be a {@link DBObject}, a
+			 *          value that is supported by MongoDB or a value that can be converted to a MongoDB representation but
+			 *          must not be {@literal null}.
+			 * @return the {@link OtherwiseBuilder}
+			 */
+			OtherwiseBuilder then(Object value);
+
+			/**
+			 * @param fieldReference must not be {@literal null}.
+			 * @return the {@link OtherwiseBuilder}
+			 */
+			OtherwiseBuilder thenValueOf(String fieldReference);
+
+			/**
+			 * @param expression must not be {@literal null}.
+			 * @return the {@link OtherwiseBuilder}
+			 */
+			OtherwiseBuilder thenValueOf(AggregationExpression expression);
+		}
+
+		/**
+		 * @author Mark Paluch
+		 */
+		public interface OtherwiseBuilder {
+
+			/**
+			 * @param value the value to be used if the condition evaluates {@literal false}. Can be a {@link DBObject}, a
+			 *          value that is supported by MongoDB or a value that can be converted to a MongoDB representation but
+			 *          must not be {@literal null}.
+			 * @return the {@link Cond}
+			 */
+			Cond otherwise(Object value);
+
+			/**
+			 * @param fieldReference must not be {@literal null}.
+			 * @return the {@link Cond}
+			 */
+			Cond otherwiseValueOf(String fieldReference);
+
+			/**
+			 * @param expression must not be {@literal null}.
+			 * @return the {@link Cond}
+			 */
+			Cond otherwiseValueOf(AggregationExpression expression);
+		}
+
+		/**
+		 * Builder for fluent {@link Cond} creation.
+		 *
+		 * @author Mark Paluch
+		 */
+		static class ConditionalExpressionBuilder implements WhenBuilder, ThenBuilder, OtherwiseBuilder {
+
+			private Object condition;
+			private Object thenValue;
+
+			private ConditionalExpressionBuilder() {}
+
+			/**
+			 * Creates a new builder for {@link Cond}.
+			 *
+			 * @return never {@literal null}.
+			 */
+			public static ConditionalExpressionBuilder newBuilder() {
+				return new ConditionalExpressionBuilder();
+			}
+
+			/* (non-Javadoc)
+			 * @see org.springframework.data.mongodb.core.aggregation.ConditionalOperators.Cond.WhenBuilder#when(com.mongodb.DBObject)
+			 */
+			@Override
+			public ConditionalExpressionBuilder when(DBObject booleanExpression) {
+
+				Assert.notNull(booleanExpression, "'Boolean expression' must not be null!");
+
+				this.condition = booleanExpression;
+				return this;
+			}
+
+			/* (non-Javadoc)
+			 * @see org.springframework.data.mongodb.core.aggregation.ConditionalOperators.Cond.WhenBuilder#when(org.springframework.data.mongodb.core.query.CriteriaDefinition)
+			 */
+			@Override
+			public ThenBuilder when(CriteriaDefinition criteria) {
+
+				Assert.notNull(criteria, "Criteria must not be null!");
+				this.condition = criteria;
+				return this;
+			}
+
+			/* (non-Javadoc)
+			 * @see org.springframework.data.mongodb.core.aggregation.ConditionalOperators.Cond.WhenBuilder#when(org.springframework.data.mongodb.core.aggregation.AggregationExpression)
+			 */
+			@Override
+			public ThenBuilder when(AggregationExpression expression) {
+
+				Assert.notNull(expression, "AggregationExpression field must not be null!");
+				this.condition = expression;
+				return this;
+			}
+
+			/* (non-Javadoc)
+			 * @see org.springframework.data.mongodb.core.aggregation.ConditionalOperators.Cond.WhenBuilder#when(java.lang.String)
+			 */
+			@Override
+			public ThenBuilder when(String booleanField) {
+
+				Assert.hasText(booleanField, "Boolean field name must not be null or empty!");
+				this.condition = Fields.field(booleanField);
+				return this;
+			}
+
+			/* (non-Javadoc)
+			 * @see org.springframework.data.mongodb.core.aggregation.ConditionalOperators.Cond.ThenBuilder#then(java.lang.Object)
+			 */
+			@Override
+			public OtherwiseBuilder then(Object thenValue) {
+
+				Assert.notNull(thenValue, "Then-value must not be null!");
+				this.thenValue = thenValue;
+				return this;
+			}
+
+			/* (non-Javadoc)
+			 * @see org.springframework.data.mongodb.core.aggregation.ConditionalOperators.Cond.ThenBuilder#thenValueOf(java.lang.String)
+			 */
+			@Override
+			public OtherwiseBuilder thenValueOf(String fieldReference) {
+
+				Assert.notNull(fieldReference, "FieldReference must not be null!");
+				this.thenValue = Fields.field(fieldReference);
+				return this;
+			}
+
+			/* (non-Javadoc)
+			 * @see org.springframework.data.mongodb.core.aggregation.ConditionalOperators.Cond.ThenBuilder#thenValueOf(org.springframework.data.mongodb.core.aggregation.AggregationExpression)
+			 */
+			@Override
+			public OtherwiseBuilder thenValueOf(AggregationExpression expression) {
+
+				Assert.notNull(expression, "AggregationExpression must not be null!");
+				this.thenValue = expression;
+				return this;
+			}
+
+			/* (non-Javadoc)
+			 * @see org.springframework.data.mongodb.core.aggregation.ConditionalOperators.Cond.OtherwiseBuilder#otherwise(java.lang.Object)
+			 */
+			@Override
+			public Cond otherwise(Object otherwiseValue) {
+
+				Assert.notNull(otherwiseValue, "Value must not be null!");
+				return new Cond(condition, thenValue, otherwiseValue);
+			}
+
+			/* (non-Javadoc)
+			 * @see org.springframework.data.mongodb.core.aggregation.ConditionalOperators.Cond.OtherwiseBuilder#otherwiseValueOf(java.lang.String)
+			 */
+			@Override
+			public Cond otherwiseValueOf(String fieldReference) {
+
+				Assert.notNull(fieldReference, "FieldReference must not be null!");
+				return new Cond(condition, thenValue, Fields.field(fieldReference));
+			}
+
+			/* (non-Javadoc)
+			 * @see org.springframework.data.mongodb.core.aggregation.ConditionalOperators.Cond.OtherwiseBuilder#otherwiseValueOf(org.springframework.data.mongodb.core.aggregation.AggregationExpression)
+			 */
+			@Override
+			public Cond otherwiseValueOf(AggregationExpression expression) {
+
+				Assert.notNull(expression, "AggregationExpression must not be null!");
+				return new Cond(condition, thenValue, expression);
+			}
+		}
+	}
+}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/CountOperation.java

@@ -0,0 +1,82 @@
+/*
+ * Copyright 2016 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb.core.aggregation;
+
+import org.springframework.data.mongodb.core.aggregation.ExposedFields.ExposedField;
+import org.springframework.util.Assert;
+
+import com.mongodb.BasicDBObject;
+import com.mongodb.DBObject;
+
+/**
+ * Encapsulates the aggregation framework {@code $count}-operation. <br />
+ * We recommend to use the static factory method {@link Aggregation#count()} instead of creating instances of this class
+ * directly.
+ *
+ * @see <a href=
+ *      "https://docs.mongodb.com/manual/reference/operator/aggregation/count/#pipe._S_count">https://docs.mongodb.com/manual/reference/operator/aggregation/count/</a>
+ * @author Mark Paluch
+ * @since 1.10
+ */
+public class CountOperation implements FieldsExposingAggregationOperation {
+
+	private final String fieldName;
+
+	/**
+	 * Creates a new {@link CountOperation} given the {@link fieldName} field name.
+	 *
+	 * @param asFieldName must not be {@literal null} or empty.
+	 */
+	public CountOperation(String fieldName) {
+
+		Assert.hasText(fieldName, "Field name must not be null or empty!");
+		this.fieldName = fieldName;
+	}
+
+	/* (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperation#toDBObject(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
+	 */
+	@Override
+	public DBObject toDBObject(AggregationOperationContext context) {
+		return new BasicDBObject("$count", fieldName);
+	}
+
+	/* (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.FieldsExposingAggregationOperation#getFields()
+	 */
+	@Override
+	public ExposedFields getFields() {
+		return ExposedFields.from(new ExposedField(fieldName, true));
+	}
+
+	/**
+	 * Builder for {@link CountOperation}.
+	 *
+	 * @author Mark Paluch
+	 */
+	public static class CountOperationBuilder {
+
+		/**
+		 * Returns the finally to be applied {@link CountOperation} with the given alias.
+		 *
+		 * @param fieldName must not be {@literal null} or empty.
+		 * @return
+		 */
+		public CountOperation as(String fieldName) {
+			return new CountOperation(fieldName);
+		}
+	}
+}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/DataTypeOperators.java

@@ -0,0 +1,67 @@
+/*
+ * Copyright 2016. the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb.core.aggregation;
+
+import org.springframework.util.Assert;
+
+/**
+ * Gateway to {@literal data type} expressions.
+ *
+ * @author Christoph Strobl
+ * @since 1.10
+ * @soundtrack Clawfinger - Catch Me
+ */
+public class DataTypeOperators {
+
+	/**
+	 * Return the BSON data type of the given {@literal field}.
+	 *
+	 * @param fieldReference must not be {@literal null}.
+	 * @return
+	 */
+	public static Type typeOf(String fieldReference) {
+		return Type.typeOf(fieldReference);
+	}
+
+	/**
+	 * {@link AggregationExpression} for {@code $type}.
+	 *
+	 * @author Christoph Strobl
+	 */
+	public static class Type extends AbstractAggregationExpression {
+
+		private Type(Object value) {
+			super(value);
+		}
+
+		@Override
+		protected String getMongoMethod() {
+			return "$type";
+		}
+
+		/**
+		 * Creates new {@link Type}.
+		 *
+		 * @param field must not be {@literal null}.
+		 * @return
+		 */
+		public static Type typeOf(String field) {
+
+			Assert.notNull(field, "Field must not be null!");
+			return new Type(Fields.field(field));
+		}
+	}
+}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/DateOperators.java

@@ -0,0 +1,837 @@
+/*
+ * Copyright 2016. the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb.core.aggregation;
+
+import java.util.LinkedHashMap;
+
+import org.springframework.data.mongodb.core.aggregation.ArithmeticOperators.ArithmeticOperatorFactory;
+import org.springframework.util.Assert;
+
+/**
+ * Gateway to {@literal Date} aggregation operations.
+ *
+ * @author Christoph Strobl
+ * @since 1.10
+ */
+public class DateOperators {
+
+	/**
+	 * Take the date referenced by given {@literal fieldReference}.
+	 *
+	 * @param fieldReference must not be {@literal null}.
+	 * @return
+	 */
+	public static DateOperatorFactory dateOf(String fieldReference) {
+
+		Assert.notNull(fieldReference, "FieldReference must not be null!");
+		return new DateOperatorFactory(fieldReference);
+	}
+
+	/**
+	 * Take the date resulting from the given {@link AggregationExpression}.
+	 *
+	 * @param expression must not be {@literal null}.
+	 * @return
+	 */
+	public static DateOperatorFactory dateOf(AggregationExpression expression) {
+
+		Assert.notNull(expression, "Expression must not be null!");
+		return new DateOperatorFactory(expression);
+	}
+
+	/**
+	 * @author Christoph Strobl
+	 */
+	public static class DateOperatorFactory {
+
+		private final String fieldReference;
+		private final AggregationExpression expression;
+
+		/**
+		 * Creates new {@link ArithmeticOperatorFactory} for given {@literal fieldReference}.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 */
+		public DateOperatorFactory(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			this.fieldReference = fieldReference;
+			this.expression = null;
+		}
+
+		/**
+		 * Creates new {@link ArithmeticOperatorFactory} for given {@link AggregationExpression}.
+		 *
+		 * @param expression must not be {@literal null}.
+		 */
+		public DateOperatorFactory(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			this.fieldReference = null;
+			this.expression = expression;
+		}
+
+		/**
+		 * Creates new {@link AggregationExpression} that returns the day of the year for a date as a number between 1 and
+		 * 366.
+		 *
+		 * @return
+		 */
+		public DayOfYear dayOfYear() {
+			return usesFieldRef() ? DayOfYear.dayOfYear(fieldReference) : DayOfYear.dayOfYear(expression);
+		}
+
+		/**
+		 * Creates new {@link AggregationExpression} that returns the day of the month for a date as a number between 1 and
+		 * 31.
+		 *
+		 * @return
+		 */
+		public DayOfMonth dayOfMonth() {
+			return usesFieldRef() ? DayOfMonth.dayOfMonth(fieldReference) : DayOfMonth.dayOfMonth(expression);
+		}
+
+		/**
+		 * Creates new {@link AggregationExpression} that returns the day of the week for a date as a number between 1
+		 * (Sunday) and 7 (Saturday).
+		 *
+		 * @return
+		 */
+		public DayOfWeek dayOfWeek() {
+			return usesFieldRef() ? DayOfWeek.dayOfWeek(fieldReference) : DayOfWeek.dayOfWeek(expression);
+		}
+
+		/**
+		 * Creates new {@link AggregationExpression} that returns the year portion of a date.
+		 *
+		 * @return
+		 */
+		public Year year() {
+			return usesFieldRef() ? Year.yearOf(fieldReference) : Year.yearOf(expression);
+		}
+
+		/**
+		 * Creates new {@link AggregationExpression} that returns the month of a date as a number between 1 and 12.
+		 *
+		 * @return
+		 */
+		public Month month() {
+			return usesFieldRef() ? Month.monthOf(fieldReference) : Month.monthOf(expression);
+		}
+
+		/**
+		 * Creates new {@link AggregationExpression} that returns the week of the year for a date as a number between 0 and
+		 * 53.
+		 *
+		 * @return
+		 */
+		public Week week() {
+			return usesFieldRef() ? Week.weekOf(fieldReference) : Week.weekOf(expression);
+		}
+
+		/**
+		 * Creates new {@link AggregationExpression} that returns the hour portion of a date as a number between 0 and 23.
+		 *
+		 * @return
+		 */
+		public Hour hour() {
+			return usesFieldRef() ? Hour.hourOf(fieldReference) : Hour.hourOf(expression);
+		}
+
+		/**
+		 * Creates new {@link AggregationExpression} that returns the minute portion of a date as a number between 0 and 59.
+		 *
+		 * @return
+		 */
+		public Minute minute() {
+			return usesFieldRef() ? Minute.minuteOf(fieldReference) : Minute.minuteOf(expression);
+		}
+
+		/**
+		 * Creates new {@link AggregationExpression} that returns the second portion of a date as a number between 0 and 59,
+		 * but can be 60 to account for leap seconds.
+		 *
+		 * @return
+		 */
+		public Second second() {
+			return usesFieldRef() ? Second.secondOf(fieldReference) : Second.secondOf(expression);
+		}
+
+		/**
+		 * Creates new {@link AggregationExpression} that returns the millisecond portion of a date as an integer between 0
+		 * and 999.
+		 *
+		 * @return
+		 */
+		public Millisecond millisecond() {
+			return usesFieldRef() ? Millisecond.millisecondOf(fieldReference) : Millisecond.millisecondOf(expression);
+		}
+
+		/**
+		 * Creates new {@link AggregationExpression} that converts a date object to a string according to a user-specified
+		 * {@literal format}.
+		 *
+		 * @param format must not be {@literal null}.
+		 * @return
+		 */
+		public DateToString toString(String format) {
+			return (usesFieldRef() ? DateToString.dateOf(fieldReference) : DateToString.dateOf(expression)).toString(format);
+		}
+
+		/**
+		 * Creates new {@link AggregationExpression} that returns the weekday number in ISO 8601 format, ranging from 1 (for
+		 * Monday) to 7 (for Sunday).
+		 *
+		 * @return
+		 */
+		public IsoDayOfWeek isoDayOfWeek() {
+			return usesFieldRef() ? IsoDayOfWeek.isoDayOfWeek(fieldReference) : IsoDayOfWeek.isoDayOfWeek(expression);
+		}
+
+		/**
+		 * Creates new {@link AggregationExpression} that returns the week number in ISO 8601 format, ranging from 1 to 53.
+		 *
+		 * @return
+		 */
+		public IsoWeek isoWeek() {
+			return usesFieldRef() ? IsoWeek.isoWeekOf(fieldReference) : IsoWeek.isoWeekOf(expression);
+		}
+
+		/**
+		 * Creates new {@link AggregationExpression} that returns the year number in ISO 8601 format.
+		 *
+		 * @return
+		 */
+		public IsoWeekYear isoWeekYear() {
+			return usesFieldRef() ? IsoWeekYear.isoWeekYearOf(fieldReference) : IsoWeekYear.isoWeekYearOf(expression);
+		}
+
+		private boolean usesFieldRef() {
+			return fieldReference != null;
+		}
+	}
+
+	/**
+	 * {@link AggregationExpression} for {@code $dayOfYear}.
+	 *
+	 * @author Christoph Strobl
+	 */
+	public static class DayOfYear extends AbstractAggregationExpression {
+
+		private DayOfYear(Object value) {
+			super(value);
+		}
+
+		@Override
+		protected String getMongoMethod() {
+			return "$dayOfYear";
+		}
+
+		/**
+		 * Creates new {@link DayOfYear}.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public static DayOfYear dayOfYear(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			return new DayOfYear(Fields.field(fieldReference));
+		}
+
+		/**
+		 * Creates new {@link DayOfYear}.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public static DayOfYear dayOfYear(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return new DayOfYear(expression);
+		}
+	}
+
+	/**
+	 * {@link AggregationExpression} for {@code $dayOfMonth}.
+	 *
+	 * @author Christoph Strobl
+	 */
+	public static class DayOfMonth extends AbstractAggregationExpression {
+
+		private DayOfMonth(Object value) {
+			super(value);
+		}
+
+		@Override
+		protected String getMongoMethod() {
+			return "$dayOfMonth";
+		}
+
+		/**
+		 * Creates new {@link DayOfMonth}.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public static DayOfMonth dayOfMonth(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			return new DayOfMonth(Fields.field(fieldReference));
+		}
+
+		/**
+		 * Creates new {@link DayOfMonth}.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public static DayOfMonth dayOfMonth(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return new DayOfMonth(expression);
+		}
+	}
+
+	/**
+	 * {@link AggregationExpression} for {@code $dayOfWeek}.
+	 *
+	 * @author Christoph Strobl
+	 */
+	public static class DayOfWeek extends AbstractAggregationExpression {
+
+		private DayOfWeek(Object value) {
+			super(value);
+		}
+
+		@Override
+		protected String getMongoMethod() {
+			return "$dayOfWeek";
+		}
+
+		/**
+		 * Creates new {@link DayOfWeek}.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public static DayOfWeek dayOfWeek(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			return new DayOfWeek(Fields.field(fieldReference));
+		}
+
+		/**
+		 * Creates new {@link DayOfWeek}.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public static DayOfWeek dayOfWeek(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return new DayOfWeek(expression);
+		}
+	}
+
+	/**
+	 * {@link AggregationExpression} for {@code $year}.
+	 *
+	 * @author Christoph Strobl
+	 */
+	public static class Year extends AbstractAggregationExpression {
+
+		private Year(Object value) {
+			super(value);
+		}
+
+		@Override
+		protected String getMongoMethod() {
+			return "$year";
+		}
+
+		/**
+		 * Creates new {@link Year}.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public static Year yearOf(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			return new Year(Fields.field(fieldReference));
+		}
+
+		/**
+		 * Creates new {@link Year}.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public static Year yearOf(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return new Year(expression);
+		}
+	}
+
+	/**
+	 * {@link AggregationExpression} for {@code $month}.
+	 *
+	 * @author Christoph Strobl
+	 */
+	public static class Month extends AbstractAggregationExpression {
+
+		private Month(Object value) {
+			super(value);
+		}
+
+		@Override
+		protected String getMongoMethod() {
+			return "$month";
+		}
+
+		/**
+		 * Creates new {@link Month}.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public static Month monthOf(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			return new Month(Fields.field(fieldReference));
+		}
+
+		/**
+		 * Creates new {@link Month}.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public static Month monthOf(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return new Month(expression);
+		}
+	}
+
+	/**
+	 * {@link AggregationExpression} for {@code $week}.
+	 *
+	 * @author Christoph Strobl
+	 */
+	public static class Week extends AbstractAggregationExpression {
+
+		private Week(Object value) {
+			super(value);
+		}
+
+		@Override
+		protected String getMongoMethod() {
+			return "$week";
+		}
+
+		/**
+		 * Creates new {@link Week}.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public static Week weekOf(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			return new Week(Fields.field(fieldReference));
+		}
+
+		/**
+		 * Creates new {@link Week}.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public static Week weekOf(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return new Week(expression);
+		}
+	}
+
+	/**
+	 * {@link AggregationExpression} for {@code $hour}.
+	 *
+	 * @author Christoph Strobl
+	 */
+	public static class Hour extends AbstractAggregationExpression {
+
+		private Hour(Object value) {
+			super(value);
+		}
+
+		@Override
+		protected String getMongoMethod() {
+			return "$hour";
+		}
+
+		/**
+		 * Creates new {@link Hour}.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public static Hour hourOf(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			return new Hour(Fields.field(fieldReference));
+		}
+
+		/**
+		 * Creates new {@link Hour}.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public static Hour hourOf(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return new Hour(expression);
+		}
+	}
+
+	/**
+	 * {@link AggregationExpression} for {@code $minute}.
+	 *
+	 * @author Christoph Strobl
+	 */
+	public static class Minute extends AbstractAggregationExpression {
+
+		private Minute(Object value) {
+			super(value);
+		}
+
+		@Override
+		protected String getMongoMethod() {
+			return "$minute";
+		}
+
+		/**
+		 * Creates new {@link Minute}.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public static Minute minuteOf(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			return new Minute(Fields.field(fieldReference));
+		}
+
+		/**
+		 * Creates new {@link Minute}.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public static Minute minuteOf(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return new Minute(expression);
+		}
+	}
+
+	/**
+	 * {@link AggregationExpression} for {@code $second}.
+	 *
+	 * @author Christoph Strobl
+	 */
+	public static class Second extends AbstractAggregationExpression {
+
+		private Second(Object value) {
+			super(value);
+		}
+
+		@Override
+		protected String getMongoMethod() {
+			return "$second";
+		}
+
+		/**
+		 * Creates new {@link Second}.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public static Second secondOf(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			return new Second(Fields.field(fieldReference));
+		}
+
+		/**
+		 * Creates new {@link Second}.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public static Second secondOf(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return new Second(expression);
+		}
+	}
+
+	/**
+	 * {@link AggregationExpression} for {@code $millisecond}.
+	 *
+	 * @author Christoph Strobl
+	 */
+	public static class Millisecond extends AbstractAggregationExpression {
+
+		private Millisecond(Object value) {
+			super(value);
+		}
+
+		@Override
+		protected String getMongoMethod() {
+			return "$millisecond";
+		}
+
+		/**
+		 * Creates new {@link Millisecond}.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public static Millisecond millisecondOf(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			return new Millisecond(Fields.field(fieldReference));
+		}
+
+		/**
+		 * Creates new {@link Millisecond}.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public static Millisecond millisecondOf(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return new Millisecond(expression);
+		}
+	}
+
+	/**
+	 * {@link AggregationExpression} for {@code $dateToString}.
+	 *
+	 * @author Christoph Strobl
+	 */
+	public static class DateToString extends AbstractAggregationExpression {
+
+		private DateToString(Object value) {
+			super(value);
+		}
+
+		@Override
+		protected String getMongoMethod() {
+			return "$dateToString";
+		}
+
+		/**
+		 * Creates new {@link FormatBuilder} allowing to define the date format to apply.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public static FormatBuilder dateOf(final String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+
+			return new FormatBuilder() {
+
+				@Override
+				public DateToString toString(String format) {
+
+					Assert.notNull(format, "Format must not be null!");
+					return new DateToString(argumentMap(Fields.field(fieldReference), format));
+				}
+			};
+		}
+
+		/**
+		 * Creates new {@link FormatBuilder} allowing to define the date format to apply.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public static FormatBuilder dateOf(final AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+
+			return new FormatBuilder() {
+
+				@Override
+				public DateToString toString(String format) {
+
+					Assert.notNull(format, "Format must not be null!");
+					return new DateToString(argumentMap(expression, format));
+				}
+			};
+		}
+
+		private static java.util.Map<String, Object> argumentMap(Object date, String format) {
+
+			java.util.Map<String, Object> args = new LinkedHashMap<String, Object>(2);
+			args.put("format", format);
+			args.put("date", date);
+			return args;
+		}
+
+		public interface FormatBuilder {
+
+			/**
+			 * Creates new {@link DateToString} with all previously added arguments appending the given one.
+			 *
+			 * @param format must not be {@literal null}.
+			 * @return
+			 */
+			DateToString toString(String format);
+		}
+	}
+
+	/**
+	 * {@link AggregationExpression} for {@code $isoDayOfWeek}.
+	 *
+	 * @author Christoph Strobl
+	 */
+	public static class IsoDayOfWeek extends AbstractAggregationExpression {
+
+		private IsoDayOfWeek(Object value) {
+			super(value);
+		}
+
+		@Override
+		protected String getMongoMethod() {
+			return "$isoDayOfWeek";
+		}
+
+		/**
+		 * Creates new {@link IsoDayOfWeek}.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public static IsoDayOfWeek isoDayOfWeek(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			return new IsoDayOfWeek(Fields.field(fieldReference));
+		}
+
+		/**
+		 * Creates new {@link IsoDayOfWeek}.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public static IsoDayOfWeek isoDayOfWeek(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return new IsoDayOfWeek(expression);
+		}
+	}
+
+	/**
+	 * {@link AggregationExpression} for {@code $isoWeek}.
+	 *
+	 * @author Christoph Strobl
+	 */
+	public static class IsoWeek extends AbstractAggregationExpression {
+
+		private IsoWeek(Object value) {
+			super(value);
+		}
+
+		@Override
+		protected String getMongoMethod() {
+			return "$isoWeek";
+		}
+
+		/**
+		 * Creates new {@link IsoWeek}.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public static IsoWeek isoWeekOf(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			return new IsoWeek(Fields.field(fieldReference));
+		}
+
+		/**
+		 * Creates new {@link IsoWeek}.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public static IsoWeek isoWeekOf(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return new IsoWeek(expression);
+		}
+	}
+
+	/**
+	 * {@link AggregationExpression} for {@code $isoWeekYear}.
+	 *
+	 * @author Christoph Strobl
+	 */
+	public static class IsoWeekYear extends AbstractAggregationExpression {
+
+		private IsoWeekYear(Object value) {
+			super(value);
+		}
+
+		@Override
+		protected String getMongoMethod() {
+			return "$isoWeekYear";
+		}
+
+		/**
+		 * Creates new {@link IsoWeekYear}.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public static IsoWeekYear isoWeekYearOf(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null!");
+			return new IsoWeekYear(Fields.field(fieldReference));
+		}
+
+		/**
+		 * Creates new {@link Millisecond}.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 */
+		public static IsoWeekYear isoWeekYearOf(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return new IsoWeekYear(expression);
+		}
+	}
+}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/ExposedFields.java

@@ -22,8 +22,10 @@ import java.util.Iterator;
 import java.util.List;
 
 import org.springframework.data.mongodb.core.aggregation.ExposedFields.ExposedField;
+import org.springframework.data.mongodb.core.aggregation.Fields.AggregationField;
 import org.springframework.util.Assert;
 import org.springframework.util.CompositeIterator;
+import org.springframework.util.ObjectUtils;
 
 /**
  * Value object to capture the fields exposed by an {@link AggregationOperation}.
@@ -104,7 +106,7 @@ public final class ExposedFields implements Iterable<ExposedField> {
 			result.add(new ExposedField(field, synthetic));
 		}
 
-		return ExposedFields.from(result);
+		return from(result);
 	}
 
 	/**
@@ -336,12 +338,36 @@ public final class ExposedFields implements Iterable<ExposedField> {
 		}
 	}
 
+	/**
+	 * A reference to an {@link ExposedField}.
+	 *
+	 * @author Christoph Strobl
+	 * @since 1.10
+	 */
+	interface FieldReference {
+
+		/**
+		 * Returns the raw, unqualified reference, i.e. the field reference without a {@literal $} prefix.
+		 *
+		 * @return
+		 */
+		String getRaw();
+
+		/**
+		 * Returns the reference value for the given field reference. Will return 1 for a synthetic, unaliased field or the
+		 * raw rendering of the reference otherwise.
+		 *
+		 * @return
+		 */
+		Object getReferenceValue();
+	}
+
 	/**
 	 * A reference to an {@link ExposedField}.
 	 * 
 	 * @author Oliver Gierke
 	 */
-	static class FieldReference {
+	static class DirectFieldReference implements FieldReference {
 
 		private final ExposedField field;
 
@@ -350,17 +376,16 @@ public final class ExposedFields implements Iterable<ExposedField> {
 		 * 
 		 * @param field must not be {@literal null}.
 		 */
-		public FieldReference(ExposedField field) {
+		public DirectFieldReference(ExposedField field) {
 
 			Assert.notNull(field, "ExposedField must not be null!");
 
 			this.field = field;
 		}
 
-		/**
-		 * Returns the raw, unqualified reference, i.e. the field reference without a {@literal $} prefix.
-		 * 
-		 * @return
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.ExposedFields.FieldReference#getRaw()
 		 */
 		public String getRaw() {
 
@@ -368,11 +393,9 @@ public final class ExposedFields implements Iterable<ExposedField> {
 			return field.synthetic ? target : String.format("%s.%s", Fields.UNDERSCORE_ID, target);
 		}
 
-		/**
-		 * Returns the reference value for the given field reference. Will return 1 for a synthetic, unaliased field or the
-		 * raw rendering of the reference otherwise.
-		 * 
-		 * @return
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.ExposedFields.FieldReference#getReferenceValue()
 		 */
 		public Object getReferenceValue() {
 			return field.synthetic && !field.isAliased() ? 1 : toString();
@@ -384,6 +407,11 @@ public final class ExposedFields implements Iterable<ExposedField> {
 		 */
 		@Override
 		public String toString() {
+
+			if(getRaw().startsWith("$")) {
+				return getRaw();
+			}
+
 			return String.format("$%s", getRaw());
 		}
 
@@ -398,11 +426,11 @@ public final class ExposedFields implements Iterable<ExposedField> {
 				return true;
 			}
 
-			if (!(obj instanceof FieldReference)) {
+			if (!(obj instanceof DirectFieldReference)) {
 				return false;
 			}
 
-			FieldReference that = (FieldReference) obj;
+			DirectFieldReference that = (DirectFieldReference) obj;
 
 			return this.field.equals(that.field);
 		}
@@ -416,4 +444,78 @@ public final class ExposedFields implements Iterable<ExposedField> {
 			return field.hashCode();
 		}
 	}
+
+	/**
+	 * A {@link FieldReference} to a {@link Field} used within a nested {@link AggregationExpression}.
+	 *
+	 * @author Christoph Strobl
+	 * @since 1.10
+	 */
+	static class ExpressionFieldReference implements FieldReference {
+
+		private FieldReference delegate;
+
+		/**
+		 * Creates a new {@link FieldReference} for the given {@link ExposedField}.
+		 *
+		 * @param field must not be {@literal null}.
+		 */
+		public ExpressionFieldReference(FieldReference field) {
+			delegate = field;
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.ExposedFields.FieldReference#getRaw()
+		 */
+		@Override
+		public String getRaw() {
+			return delegate.getRaw();
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.ExposedFields.FieldReference#getReferenceValue()
+		 */
+		@Override
+		public Object getReferenceValue() {
+			return delegate.getReferenceValue();
+		}
+
+		@Override
+		public String toString() {
+
+			String fieldRef = delegate.toString();
+
+			if (fieldRef.startsWith("$$")) {
+				return fieldRef;
+			}
+
+			if (fieldRef.startsWith("$")) {
+				return "$" + fieldRef;
+			}
+
+			return fieldRef;
+		}
+
+		@Override
+		public boolean equals(Object obj) {
+
+			if (this == obj) {
+				return true;
+			}
+
+			if (!(obj instanceof ExpressionFieldReference)) {
+				return false;
+			}
+
+			ExpressionFieldReference that = (ExpressionFieldReference) obj;
+			return ObjectUtils.nullSafeEquals(this.delegate, that.delegate);
+		}
+
+		@Override
+		public int hashCode() {
+			return delegate.hashCode();
+		}
+	}
 }

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/ExposedFieldsAggregationOperationContext.java

@@ -15,11 +15,13 @@
  */
 package org.springframework.data.mongodb.core.aggregation;
 
-import org.bson.Document;
 import org.springframework.data.mongodb.core.aggregation.ExposedFields.ExposedField;
+import org.springframework.data.mongodb.core.aggregation.ExposedFields.DirectFieldReference;
 import org.springframework.data.mongodb.core.aggregation.ExposedFields.FieldReference;
 import org.springframework.util.Assert;
 
+import com.mongodb.DBObject;
+
 /**
  * {@link AggregationOperationContext} that combines the available field references from a given
  * {@code AggregationOperationContext} and an {@link FieldsExposingAggregationOperation}.
@@ -27,7 +29,6 @@ import org.springframework.util.Assert;
  * @author Thomas Darimont
  * @author Oliver Gierke
  * @author Mark Paluch
- * @author Christoph Strobl
  * @since 1.4
  */
 class ExposedFieldsAggregationOperationContext implements AggregationOperationContext {
@@ -54,11 +55,11 @@ class ExposedFieldsAggregationOperationContext implements AggregationOperationCo
 
 	/* 
 	 * (non-Javadoc)
-	 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperationContext#getMappedObject(com.mongodb.Document)
+	 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperationContext#getMappedObject(com.mongodb.DBObject)
 	 */
 	@Override
-	public Document getMappedObject(Document document) {
-		return rootContext.getMappedObject(document);
+	public DBObject getMappedObject(DBObject dbObject) {
+		return rootContext.getMappedObject(dbObject);
 	}
 
 	/* 
@@ -112,10 +113,10 @@ class ExposedFieldsAggregationOperationContext implements AggregationOperationCo
 
 			if (field != null) {
 				// we return a FieldReference to the given field directly to make sure that we reference the proper alias here.
-				return new FieldReference(new ExposedField(field, exposedField.isSynthetic()));
+				return new DirectFieldReference(new ExposedField(field, exposedField.isSynthetic()));
 			}
 
-			return new FieldReference(exposedField);
+			return new DirectFieldReference(exposedField);
 		}
 
 		if (name.contains(".")) {
@@ -126,7 +127,7 @@ class ExposedFieldsAggregationOperationContext implements AggregationOperationCo
 			if (rootField != null) {
 
 				// We have to synthetic to true, in order to render the field-name as is.
-				return new FieldReference(new ExposedField(name, true));
+				return new DirectFieldReference(new ExposedField(name, true));
 			}
 		}
 		return null;

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/FacetOperation.java

@@ -0,0 +1,228 @@
+/*
+ * Copyright 2016-2017 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb.core.aggregation;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+
+import org.springframework.data.mongodb.core.aggregation.BucketOperationSupport.Output;
+import org.springframework.data.mongodb.core.aggregation.ExposedFields.ExposedField;
+import org.springframework.util.Assert;
+
+import com.mongodb.BasicDBObject;
+import com.mongodb.DBObject;
+
+/**
+ * Encapsulates the aggregation framework {@code $facet}-operation. <br />
+ * Facet of {@link AggregationOperation}s to be used in an {@link Aggregation}. Processes multiple
+ * {@link AggregationOperation} pipelines within a single stage on the same set of input documents. Each sub-pipeline
+ * has its own field in the output document where its results are stored as an array of documents.
+ * {@link FacetOperation} enables various aggregations on the same set of input documents, without needing to retrieve
+ * the input documents multiple times. <br />
+ * As of MongoDB 3.4, {@link FacetOperation} cannot be used with nested pipelines containing {@link GeoNearOperation},
+ * {@link OutOperation} and {@link FacetOperation}. <br />
+ * We recommend to use the static factory method {@link Aggregation#facet()} instead of creating instances of this class
+ * directly.
+ *
+ * @author Mark Paluch
+ * @author Christoph Strobl
+ * @since 1.10
+ * @see <a href="https://docs.mongodb.org/manual/reference/aggregation/facet/">MongoDB Aggregation Framework: $facet</a>
+ */
+public class FacetOperation implements FieldsExposingAggregationOperation {
+
+	/**
+	 * Empty (initial) {@link FacetOperation}.
+	 */
+	public static final FacetOperation EMPTY = new FacetOperation();
+
+	private final Facets facets;
+
+	/**
+	 * Creates a new {@link FacetOperation}.
+	 */
+	public FacetOperation() {
+		this(Facets.EMPTY);
+	}
+
+	private FacetOperation(Facets facets) {
+		this.facets = facets;
+	}
+
+	/**
+	 * Creates a new {@link FacetOperationBuilder} to append a new facet using {@literal operations}. <br />
+	 * {@link FacetOperationBuilder} takes a pipeline of {@link AggregationOperation} to categorize documents into a
+	 * single facet.
+	 *
+	 * @param operations must not be {@literal null} or empty.
+	 * @return
+	 */
+	public FacetOperationBuilder and(AggregationOperation... operations) {
+
+		Assert.notNull(operations, "AggregationOperations must not be null!");
+		Assert.notEmpty(operations, "AggregationOperations must not be empty!");
+
+		return new FacetOperationBuilder(facets, Arrays.asList(operations));
+	}
+
+	/* (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperation#toDBObject(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
+	 */
+	@Override
+	public DBObject toDBObject(AggregationOperationContext context) {
+		return new BasicDBObject("$facet", facets.toDBObject(context));
+	}
+
+	/* (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.FieldsExposingAggregationOperation#getFields()
+	 */
+	@Override
+	public ExposedFields getFields() {
+		return facets.asExposedFields();
+	}
+
+	/**
+	 * Builder for {@link FacetOperation} by adding existing and the new pipeline of {@link AggregationOperation} to the
+	 * new {@link FacetOperation}.
+	 *
+	 * @author Mark Paluch
+	 */
+	public static class FacetOperationBuilder {
+
+		private final Facets current;
+		private final List<AggregationOperation> operations;
+
+		private FacetOperationBuilder(Facets current, List<AggregationOperation> operations) {
+			this.current = current;
+			this.operations = operations;
+		}
+
+		/**
+		 * Creates a new {@link FacetOperation} that contains the configured pipeline of {@link AggregationOperation}
+		 * exposed as {@literal fieldName} in the resulting facet document.
+		 *
+		 * @param fieldName must not be {@literal null} or empty.
+		 * @return
+		 */
+		public FacetOperation as(String fieldName) {
+
+			Assert.hasText(fieldName, "FieldName must not be null or empty!");
+
+			return new FacetOperation(current.and(fieldName, operations));
+		}
+	}
+
+	/**
+	 * Encapsulates multiple {@link Facet}s
+	 *
+	 * @author Mark Paluch
+	 */
+	private static class Facets {
+
+		private static final Facets EMPTY = new Facets(Collections.<Facet> emptyList());
+
+		private List<Facet> facets;
+
+		/**
+		 * Creates a new {@link Facets} given {@link List} of {@link Facet}.
+		 *
+		 * @param facets
+		 */
+		private Facets(List<Facet> facets) {
+			this.facets = facets;
+		}
+
+		/**
+		 * @return the {@link ExposedFields} derived from {@link Output}.
+		 */
+		ExposedFields asExposedFields() {
+
+			ExposedFields fields = ExposedFields.from();
+
+			for (Facet facet : facets) {
+				fields = fields.and(facet.getExposedField());
+			}
+
+			return fields;
+		}
+
+		DBObject toDBObject(AggregationOperationContext context) {
+
+			DBObject dbObject = new BasicDBObject(facets.size());
+
+			for (Facet facet : facets) {
+				dbObject.put(facet.getExposedField().getName(), facet.toDBObjects(context));
+			}
+
+			return dbObject;
+		}
+
+		/**
+		 * Adds a facet to this {@link Facets}.
+		 *
+		 * @param fieldName must not be {@literal null}.
+		 * @param operations must not be {@literal null}.
+		 * @return the new {@link Facets}.
+		 */
+		Facets and(String fieldName, List<AggregationOperation> operations) {
+
+			Assert.hasText(fieldName, "FieldName must not be null or empty!");
+			Assert.notNull(operations, "AggregationOperations must not be null!");
+
+			List<Facet> facets = new ArrayList<Facet>(this.facets.size() + 1);
+			facets.addAll(this.facets);
+			facets.add(new Facet(new ExposedField(fieldName, true), operations));
+
+			return new Facets(facets);
+		}
+	}
+
+	/**
+	 * A single facet with a {@link ExposedField} and its {@link AggregationOperation} pipeline.
+	 *
+	 * @author Mark Paluch
+	 */
+	private static class Facet {
+
+		private final ExposedField exposedField;
+		private final List<AggregationOperation> operations;
+
+		/**
+		 * Creates a new {@link Facet} given {@link ExposedField} and {@link AggregationOperation} pipeline.
+		 *
+		 * @param exposedField must not be {@literal null}.
+		 * @param operations must not be {@literal null}.
+		 */
+		Facet(ExposedField exposedField, List<AggregationOperation> operations) {
+
+			Assert.notNull(exposedField, "ExposedField must not be null!");
+			Assert.notNull(operations, "AggregationOperations must not be null!");
+
+			this.exposedField = exposedField;
+			this.operations = operations;
+		}
+
+		ExposedField getExposedField() {
+			return exposedField;
+		}
+
+		List<DBObject> toDBObjects(AggregationOperationContext context) {
+			return AggregationOperationRenderer.toDBObject(operations, context);
+		}
+	}
+}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/Fields.java

@@ -17,6 +17,7 @@ package org.springframework.data.mongodb.core.aggregation;
 
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.HashMap;
 import java.util.Iterator;
 import java.util.List;
@@ -185,6 +186,14 @@ public final class Fields implements Iterable<Field> {
 		return fields.iterator();
 	}
 
+	/**
+	 * @return
+	 * @since 1.10
+	 */
+	public List<Field> asList() {
+		return Collections.unmodifiableList(fields);
+	}
+
 	/**
 	 * Value object to encapsulate a field in an aggregation operation.
 	 * 
@@ -192,6 +201,7 @@ public final class Fields implements Iterable<Field> {
 	 */
 	static class AggregationField implements Field {
 
+		private final String raw;
 		private final String name;
 		private final String target;
 
@@ -216,6 +226,7 @@ public final class Fields implements Iterable<Field> {
 		 */
 		public AggregationField(String name, String target) {
 
+			raw = name;
 			String nameToSet = cleanUp(name);
 			String targetToSet = cleanUp(target);
 
@@ -257,6 +268,11 @@ public final class Fields implements Iterable<Field> {
 		 * @see org.springframework.data.mongodb.core.aggregation.Field#getAlias()
 		 */
 		public String getTarget() {
+
+			if (isLocalVar()) {
+				return this.getRaw();
+			}
+
 			return StringUtils.hasText(this.target) ? this.target : this.name;
 		}
 
@@ -269,6 +285,22 @@ public final class Fields implements Iterable<Field> {
 			return !getName().equals(getTarget());
 		}
 
+		/**
+		 * @return {@literal true} in case the field name starts with {@code $$}.
+		 * @since 1.10
+		 */
+		public boolean isLocalVar() {
+			return raw.startsWith("$$") && !raw.startsWith("$$$");
+		}
+
+		/**
+		 * @return
+		 * @since 1.10
+		 */
+		public String getRaw() {
+			return raw;
+		}
+
 		/* 
 		 * (non-Javadoc)
 		 * @see java.lang.Object#toString()

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/GeoNearOperation.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2016 the original author or authors.
+ * Copyright 2013-2015 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -15,10 +15,12 @@
  */
 package org.springframework.data.mongodb.core.aggregation;
 
-import org.bson.Document;
 import org.springframework.data.mongodb.core.query.NearQuery;
 import org.springframework.util.Assert;
 
+import com.mongodb.BasicDBObject;
+import com.mongodb.DBObject;
+
 /**
  * Represents a {@code geoNear} aggregation operation.
  * <p>
@@ -26,7 +28,6 @@ import org.springframework.util.Assert;
  * instances of this class directly.
  * 
  * @author Thomas Darimont
- * @author Christoph Strobl
  * @since 1.3
  */
 public class GeoNearOperation implements AggregationOperation {
@@ -52,14 +53,14 @@ public class GeoNearOperation implements AggregationOperation {
 
 	/* 
 	 * (non-Javadoc)
-	 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperation#toDocument(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
+	 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperation#toDBObject(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
 	 */
 	@Override
-	public Document toDocument(AggregationOperationContext context) {
+	public DBObject toDBObject(AggregationOperationContext context) {
 
-		Document command = context.getMappedObject(nearQuery.toDocument());
+		BasicDBObject command = (BasicDBObject) context.getMappedObject(nearQuery.toDBObject());
 		command.put("distanceField", distanceField);
 
-		return new Document("$geoNear", command);
+		return new BasicDBObject("$geoNear", command);
 	}
 }

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/GraphLookupOperation.java

@@ -0,0 +1,411 @@
+/*
+ * Copyright 2016-2017 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb.core.aggregation;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+
+import org.springframework.data.mongodb.core.aggregation.ExposedFields.ExposedField;
+import org.springframework.data.mongodb.core.aggregation.FieldsExposingAggregationOperation.InheritsFieldsAggregationOperation;
+import org.springframework.data.mongodb.core.query.CriteriaDefinition;
+import org.springframework.util.Assert;
+import org.springframework.util.ClassUtils;
+
+import com.mongodb.BasicDBObject;
+import com.mongodb.DBObject;
+
+/**
+ * Encapsulates the aggregation framework {@code $graphLookup}-operation. <br />
+ * Performs a recursive search on a collection, with options for restricting the search by recursion depth and query
+ * filter. <br />
+ * We recommend to use the static factory method {@link Aggregation#graphLookup(String)} instead of creating instances
+ * of this class directly.
+ *
+ * @see <a href=
+ *      "https://docs.mongodb.org/manual/reference/aggregation/graphLookup/">https://docs.mongodb.org/manual/reference/aggregation/graphLookup/</a>
+ * @author Mark Paluch
+ * @author Christoph Strobl
+ * @since 1.10
+ */
+public class GraphLookupOperation implements InheritsFieldsAggregationOperation {
+
+	private static final Set<Class<?>> ALLOWED_START_TYPES = new HashSet<Class<?>>(
+			Arrays.<Class<?>> asList(AggregationExpression.class, String.class, Field.class, DBObject.class));
+
+	private final String from;
+	private final List<Object> startWith;
+	private final Field connectFrom;
+	private final Field connectTo;
+	private final Field as;
+	private final Long maxDepth;
+	private final Field depthField;
+	private final CriteriaDefinition restrictSearchWithMatch;
+
+	private GraphLookupOperation(String from, List<Object> startWith, Field connectFrom, Field connectTo, Field as,
+			Long maxDepth, Field depthField, CriteriaDefinition restrictSearchWithMatch) {
+
+		this.from = from;
+		this.startWith = startWith;
+		this.connectFrom = connectFrom;
+		this.connectTo = connectTo;
+		this.as = as;
+		this.maxDepth = maxDepth;
+		this.depthField = depthField;
+		this.restrictSearchWithMatch = restrictSearchWithMatch;
+	}
+
+	/**
+	 * Creates a new {@link FromBuilder} to build {@link GraphLookupOperation}.
+	 *
+	 * @return a new {@link FromBuilder}.
+	 */
+	public static FromBuilder builder() {
+		return new GraphLookupOperationFromBuilder();
+	}
+
+	/* (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperation#toDBObject(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
+	 */
+	@Override
+	public DBObject toDBObject(AggregationOperationContext context) {
+
+		DBObject graphLookup = new BasicDBObject();
+
+		graphLookup.put("from", from);
+
+		List<Object> mappedStartWith = new ArrayList<Object>(startWith.size());
+
+		for (Object startWithElement : startWith) {
+
+			if (startWithElement instanceof AggregationExpression) {
+				mappedStartWith.add(((AggregationExpression) startWithElement).toDbObject(context));
+			} else if (startWithElement instanceof Field) {
+				mappedStartWith.add(context.getReference((Field) startWithElement).toString());
+			} else {
+				mappedStartWith.add(startWithElement);
+			}
+		}
+
+		graphLookup.put("startWith", mappedStartWith.size() == 1 ? mappedStartWith.iterator().next() : mappedStartWith);
+
+		graphLookup.put("connectFromField", connectFrom.getName());
+		graphLookup.put("connectToField", connectTo.getName());
+		graphLookup.put("as", as.getName());
+
+		if (maxDepth != null) {
+			graphLookup.put("maxDepth", maxDepth);
+		}
+
+		if (depthField != null) {
+			graphLookup.put("depthField", depthField.getName());
+		}
+
+		if (restrictSearchWithMatch != null) {
+			graphLookup.put("restrictSearchWithMatch", context.getMappedObject(restrictSearchWithMatch.getCriteriaObject()));
+		}
+
+		return new BasicDBObject("$graphLookup", graphLookup);
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.FieldsExposingAggregationOperation#getFields()
+	 */
+	@Override
+	public ExposedFields getFields() {
+		return ExposedFields.from(new ExposedField(as, true));
+	}
+
+	/**
+	 * @author Mark Paluch
+	 */
+	public interface FromBuilder {
+
+		/**
+		 * Set the {@literal collectionName} to apply the {@code $graphLookup} to.
+		 *
+		 * @param collectionName must not be {@literal null} or empty.
+		 * @return
+		 */
+		StartWithBuilder from(String collectionName);
+	}
+
+	/**
+	 * @author Mark Paluch
+	 * @author Christoph Strobl
+	 */
+	public interface StartWithBuilder {
+
+		/**
+		 * Set the startWith {@literal fieldReferences} to apply the {@code $graphLookup} to.
+		 *
+		 * @param fieldReferences must not be {@literal null}.
+		 * @return
+		 */
+		ConnectFromBuilder startWith(String... fieldReferences);
+
+		/**
+		 * Set the startWith {@literal expressions} to apply the {@code $graphLookup} to.
+		 *
+		 * @param expressions must not be {@literal null}.
+		 * @return
+		 */
+		ConnectFromBuilder startWith(AggregationExpression... expressions);
+
+		/**
+		 * Set the startWith as either {@literal fieldReferences}, {@link Fields}, {@link DBObject} or
+		 * {@link AggregationExpression} to apply the {@code $graphLookup} to.
+		 *
+		 * @param expressions must not be {@literal null}.
+		 * @return
+		 * @throws IllegalArgumentException
+		 */
+		ConnectFromBuilder startWith(Object... expressions);
+	}
+
+	/**
+	 * @author Mark Paluch
+	 */
+	public interface ConnectFromBuilder {
+
+		/**
+		 * Set the connectFrom {@literal fieldName} to apply the {@code $graphLookup} to.
+		 *
+		 * @param fieldName must not be {@literal null} or empty.
+		 * @return
+		 */
+		ConnectToBuilder connectFrom(String fieldName);
+	}
+
+	/**
+	 * @author Mark Paluch
+	 */
+	public interface ConnectToBuilder {
+
+		/**
+		 * Set the connectTo {@literal fieldName} to apply the {@code $graphLookup} to.
+		 *
+		 * @param fieldName must not be {@literal null} or empty.
+		 * @return
+		 */
+		GraphLookupOperationBuilder connectTo(String fieldName);
+	}
+
+	/**
+	 * Builder to build the initial {@link GraphLookupOperationBuilder} that configures the initial mandatory set of
+	 * {@link GraphLookupOperation} properties.
+	 *
+	 * @author Mark Paluch
+	 */
+	static final class GraphLookupOperationFromBuilder
+			implements FromBuilder, StartWithBuilder, ConnectFromBuilder, ConnectToBuilder {
+
+		private String from;
+		private List<? extends Object> startWith;
+		private String connectFrom;
+
+		/* (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.GraphLookupOperation.FromBuilder#from(java.lang.String)
+		 */
+		@Override
+		public StartWithBuilder from(String collectionName) {
+
+			Assert.hasText(collectionName, "CollectionName must not be null or empty!");
+
+			this.from = collectionName;
+			return this;
+		}
+
+		/* (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.GraphLookupOperation.StartWithBuilder#startWith(java.lang.String[])
+		 */
+		@Override
+		public ConnectFromBuilder startWith(String... fieldReferences) {
+
+			Assert.notNull(fieldReferences, "FieldReferences must not be null!");
+			Assert.noNullElements(fieldReferences, "FieldReferences must not contain null elements!");
+
+			List<Object> fields = new ArrayList<Object>(fieldReferences.length);
+
+			for (String fieldReference : fieldReferences) {
+				fields.add(Fields.field(fieldReference));
+			}
+
+			this.startWith = fields;
+			return this;
+		}
+
+		/* (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.GraphLookupOperation.StartWithBuilder#startWith(org.springframework.data.mongodb.core.aggregation.AggregationExpression[])
+		 */
+		@Override
+		public ConnectFromBuilder startWith(AggregationExpression... expressions) {
+
+			Assert.notNull(expressions, "AggregationExpressions must not be null!");
+			Assert.noNullElements(expressions, "AggregationExpressions must not contain null elements!");
+
+			this.startWith = Arrays.asList(expressions);
+			return this;
+		}
+
+		@Override
+		public ConnectFromBuilder startWith(Object... expressions) {
+
+			Assert.notNull(expressions, "Expressions must not be null!");
+			Assert.noNullElements(expressions, "Expressions must not contain null elements!");
+
+			this.startWith = verifyAndPotentiallyTransformStartsWithTypes(expressions);
+			return this;
+		}
+
+		private List<Object> verifyAndPotentiallyTransformStartsWithTypes(Object... expressions) {
+
+			List<Object> expressionsToUse = new ArrayList<Object>(expressions.length);
+
+			for (Object expression : expressions) {
+
+				assertStartWithType(expression);
+
+				if (expression instanceof String) {
+					expressionsToUse.add(Fields.field((String) expression));
+				} else {
+					expressionsToUse.add(expression);
+				}
+
+			}
+			return expressionsToUse;
+		}
+
+		private void assertStartWithType(Object expression) {
+
+			for (Class<?> type : ALLOWED_START_TYPES) {
+
+				if (ClassUtils.isAssignable(type, expression.getClass())) {
+					return;
+				}
+			}
+
+			throw new IllegalArgumentException(
+					String.format("Expression must be any of %s but was %s", ALLOWED_START_TYPES, expression.getClass()));
+		}
+
+		/* (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.GraphLookupOperation.ConnectFromBuilder#connectFrom(java.lang.String)
+		 */
+		@Override
+		public ConnectToBuilder connectFrom(String fieldName) {
+
+			Assert.hasText(fieldName, "ConnectFrom must not be null or empty!");
+
+			this.connectFrom = fieldName;
+			return this;
+		}
+
+		/* (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.GraphLookupOperation.ConnectToBuilder#connectTo(java.lang.String)
+		 */
+		@Override
+		public GraphLookupOperationBuilder connectTo(String fieldName) {
+
+			Assert.hasText(fieldName, "ConnectTo must not be null or empty!");
+
+			return new GraphLookupOperationBuilder(from, startWith, connectFrom, fieldName);
+		}
+	}
+
+	/**
+	 * @author Mark Paluch
+	 */
+	public static final class GraphLookupOperationBuilder {
+
+		private final String from;
+		private final List<Object> startWith;
+		private final Field connectFrom;
+		private final Field connectTo;
+		private Long maxDepth;
+		private Field depthField;
+		private CriteriaDefinition restrictSearchWithMatch;
+
+		protected GraphLookupOperationBuilder(String from, List<? extends Object> startWith, String connectFrom,
+				String connectTo) {
+
+			this.from = from;
+			this.startWith = new ArrayList<Object>(startWith);
+			this.connectFrom = Fields.field(connectFrom);
+			this.connectTo = Fields.field(connectTo);
+		}
+
+		/**
+		 * Optionally limit the number of recursions.
+		 *
+		 * @param numberOfRecursions must be greater or equal to zero.
+		 * @return
+		 */
+		public GraphLookupOperationBuilder maxDepth(long numberOfRecursions) {
+
+			Assert.isTrue(numberOfRecursions >= 0, "Max depth must be >= 0!");
+
+			this.maxDepth = numberOfRecursions;
+			return this;
+		}
+
+		/**
+		 * Optionally add a depth field {@literal fieldName} to each traversed document in the search path.
+		 *
+		 * @param fieldName must not be {@literal null} or empty.
+		 * @return
+		 */
+		public GraphLookupOperationBuilder depthField(String fieldName) {
+
+			Assert.hasText(fieldName, "Depth field name must not be null or empty!");
+
+			this.depthField = Fields.field(fieldName);
+			return this;
+		}
+
+		/**
+		 * Optionally add a query specifying conditions to the recursive search.
+		 *
+		 * @param criteriaDefinition must not be {@literal null}.
+		 * @return
+		 */
+		public GraphLookupOperationBuilder restrict(CriteriaDefinition criteriaDefinition) {
+
+			Assert.notNull(criteriaDefinition, "CriteriaDefinition must not be null!");
+
+			this.restrictSearchWithMatch = criteriaDefinition;
+			return this;
+		}
+
+		/**
+		 * Set the name of the array field added to each output document and return the final {@link GraphLookupOperation}.
+		 * Contains the documents traversed in the {@literal $graphLookup} stage to reach the document.
+		 *
+		 * @param fieldName must not be {@literal null} or empty.
+		 * @return the final {@link GraphLookupOperation}.
+		 */
+		public GraphLookupOperation as(String fieldName) {
+
+			Assert.hasText(fieldName, "As field name must not be null or empty!");
+
+			return new GraphLookupOperation(from, startWith, connectFrom, connectTo, Fields.field(fieldName), maxDepth,
+					depthField, restrictSearchWithMatch);
+		}
+	}
+}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/GroupOperation.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2016 the original author or authors.
+ * Copyright 2013-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,24 +21,27 @@ import java.util.Collections;
 import java.util.List;
 import java.util.Locale;
 
-import org.bson.Document;
 import org.springframework.data.mongodb.core.aggregation.ExposedFields.ExposedField;
 import org.springframework.data.mongodb.core.aggregation.ExposedFields.FieldReference;
 import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
 
+import com.mongodb.BasicDBObject;
+import com.mongodb.DBObject;
+
 /**
  * Encapsulates the aggregation framework {@code $group}-operation.
  * <p>
  * We recommend to use the static factory method {@link Aggregation#group(Fields)} instead of creating instances of this
  * class directly.
  * 
- * @see http://docs.mongodb.org/manual/reference/aggregation/group/#stage._S_group
  * @author Sebastian Herold
  * @author Thomas Darimont
  * @author Oliver Gierke
+ * @author Gustavo de Geus
  * @author Christoph Strobl
  * @since 1.3
+ * @see <a href="https://docs.mongodb.org/manual/reference/aggregation/group/">MongoDB Aggregation Framework: $group</a>
  */
 public class GroupOperation implements FieldsExposingAggregationOperation {
 
@@ -193,8 +196,7 @@ public class GroupOperation implements FieldsExposingAggregationOperation {
 	}
 
 	/**
-	 * Generates an {@link GroupOperationBuilder} for an {@code $last}-expression for the given
-	 * {@link AggregationExpression}.
+	 * Generates an {@link GroupOperationBuilder} for an {@code $last}-expression for the given {@link AggregationExpression}.
 	 * 
 	 * @param expr
 	 * @return
@@ -214,8 +216,7 @@ public class GroupOperation implements FieldsExposingAggregationOperation {
 	}
 
 	/**
-	 * Generates an {@link GroupOperationBuilder} for a {@code $first}-expression for the given
-	 * {@link AggregationExpression}.
+	 * Generates an {@link GroupOperationBuilder} for a {@code $first}-expression for the given {@link AggregationExpression}.
 	 * 
 	 * @param expr
 	 * @return
@@ -235,8 +236,7 @@ public class GroupOperation implements FieldsExposingAggregationOperation {
 	}
 
 	/**
-	 * Generates an {@link GroupOperationBuilder} for an {@code $avg}-expression for the given
-	 * {@link AggregationExpression}.
+	 * Generates an {@link GroupOperationBuilder} for an {@code $avg}-expression for the given {@link AggregationExpression}.
 	 * 
 	 * @param expr
 	 * @return
@@ -280,8 +280,7 @@ public class GroupOperation implements FieldsExposingAggregationOperation {
 	}
 
 	/**
-	 * Generates an {@link GroupOperationBuilder} for an {@code $min}-expression that for the given
-	 * {@link AggregationExpression}.
+	 * Generates an {@link GroupOperationBuilder} for an {@code $min}-expression that for the given {@link AggregationExpression}.
 	 * 
 	 * @param expr
 	 * @return
@@ -301,8 +300,7 @@ public class GroupOperation implements FieldsExposingAggregationOperation {
 	}
 
 	/**
-	 * Generates an {@link GroupOperationBuilder} for an {@code $max}-expression that for the given
-	 * {@link AggregationExpression}.
+	 * Generates an {@link GroupOperationBuilder} for an {@code $max}-expression that for the given {@link AggregationExpression}.
 	 * 
 	 * @param expr
 	 * @return
@@ -311,6 +309,51 @@ public class GroupOperation implements FieldsExposingAggregationOperation {
 		return newBuilder(GroupOps.MAX, null, expr);
 	}
 
+	/**
+	 * Generates an {@link GroupOperationBuilder} for an {@code $stdDevSamp}-expression that for the given
+	 * field-reference.
+	 *
+	 * @param reference must not be {@literal null}.
+	 * @return never {@literal null}.
+	 * @since 1.10
+	 */
+	public GroupOperationBuilder stdDevSamp(String reference) {
+		return newBuilder(GroupOps.STD_DEV_SAMP, reference, null);
+	}
+
+	/**
+	 * Generates an {@link GroupOperationBuilder} for an {@code $stdDevSamp}-expression that for the given {@link AggregationExpression}.
+	 *
+	 * @param expr must not be {@literal null}.
+	 * @return never {@literal null}.
+	 * @since 1.10
+	 */
+	public GroupOperationBuilder stdDevSamp(AggregationExpression expr) {
+		return newBuilder(GroupOps.STD_DEV_SAMP, null, expr);
+	}
+
+	/**
+	 * Generates an {@link GroupOperationBuilder} for an {@code $stdDevPop}-expression that for the given field-reference.
+	 *
+	 * @param reference must not be {@literal null}.
+	 * @return never {@literal null}.
+	 * @since 1.10
+	 */
+	public GroupOperationBuilder stdDevPop(String reference) {
+		return newBuilder(GroupOps.STD_DEV_POP, reference, null);
+	}
+
+	/**
+	 * Generates an {@link GroupOperationBuilder} for an {@code $stdDevPop}-expression that for the given {@link AggregationExpression}.
+	 *
+	 * @param expr must not be {@literal null}.
+	 * @return never {@literal null}.
+	 * @since 1.10
+	 */
+	public GroupOperationBuilder stdDevPop(AggregationExpression expr) {
+		return newBuilder(GroupOps.STD_DEV_POP, null, expr);
+	}
+
 	private GroupOperationBuilder newBuilder(Keyword keyword, String reference, Object value) {
 		return new GroupOperationBuilder(this, new Operation(keyword, null, reference, value));
 	}
@@ -333,12 +376,12 @@ public class GroupOperation implements FieldsExposingAggregationOperation {
 
 	/*
 	 * (non-Javadoc)
-	 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperation#toDocument(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
+	 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperation#toDBObject(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
 	 */
 	@Override
-	public Document toDocument(AggregationOperationContext context) {
+	public com.mongodb.DBObject toDBObject(AggregationOperationContext context) {
 
-		Document operationObject = new Document();
+		BasicDBObject operationObject = new BasicDBObject();
 
 		if (idFields.exposesNoNonSyntheticFields()) {
 
@@ -351,7 +394,7 @@ public class GroupOperation implements FieldsExposingAggregationOperation {
 
 		} else {
 
-			Document inner = new Document();
+			BasicDBObject inner = new BasicDBObject();
 
 			for (ExposedField field : idFields) {
 				FieldReference reference = context.getReference(field);
@@ -362,10 +405,10 @@ public class GroupOperation implements FieldsExposingAggregationOperation {
 		}
 
 		for (Operation operation : operations) {
-			operationObject.putAll(operation.toDocument(context));
+			operationObject.putAll(operation.toDBObject(context));
 		}
 
-		return new Document("$group", operationObject);
+		return new BasicDBObject("$group", operationObject);
 	}
 
 	interface Keyword {
@@ -375,21 +418,18 @@ public class GroupOperation implements FieldsExposingAggregationOperation {
 
 	private static enum GroupOps implements Keyword {
 
-		SUM, LAST, FIRST, PUSH, AVG, MIN, MAX, ADD_TO_SET, COUNT;
+		SUM("$sum"), LAST("$last"), FIRST("$first"), PUSH("$push"), AVG("$avg"), MIN("$min"), MAX("$max"), ADD_TO_SET("$addToSet"), STD_DEV_POP("$stdDevPop"), STD_DEV_SAMP("$stdDevSamp");
+
+		private String mongoOperator;
+
+		GroupOps(String mongoOperator) {
+			this.mongoOperator = mongoOperator;
+		}
+
 
 		@Override
 		public String toString() {
-
-			String[] parts = name().split("_");
-
-			StringBuilder builder = new StringBuilder();
-
-			for (String part : parts) {
-				String lowerCase = part.toLowerCase(Locale.US);
-				builder.append(builder.length() == 0 ? lowerCase : StringUtils.capitalize(lowerCase));
-			}
-
-			return "$" + builder.toString();
+			return mongoOperator;
 		}
 	}
 
@@ -416,8 +456,8 @@ public class GroupOperation implements FieldsExposingAggregationOperation {
 			return new ExposedField(key, true);
 		}
 
-		public Document toDocument(AggregationOperationContext context) {
-			return new Document(key, new Document(op.toString(), getValue(context)));
+		public DBObject toDBObject(AggregationOperationContext context) {
+			return new BasicDBObject(key, new BasicDBObject(op.toString(), getValue(context)));
 		}
 
 		public Object getValue(AggregationOperationContext context) {
@@ -425,7 +465,7 @@ public class GroupOperation implements FieldsExposingAggregationOperation {
 			if (reference == null) {
 
 				if (value instanceof AggregationExpression) {
-					return ((AggregationExpression) value).toDocument(context);
+					return ((AggregationExpression) value).toDbObject(context);
 				}
 
 				return value;

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/IfNullOperator.java

@@ -1,195 +0,0 @@
-/*
- * Copyright 2016 the original author or authors.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-package org.springframework.data.mongodb.core.aggregation;
-
-import java.util.ArrayList;
-import java.util.List;
-
-import org.bson.Document;
-import org.springframework.util.Assert;
-
-/**
- * Encapsulates the aggregation framework {@code $ifNull} operator. Replacement values can be either {@link Field field
- * references}, values of simple MongoDB types or values that can be converted to a simple MongoDB type.
- *
- * @see http://docs.mongodb.com/manual/reference/operator/aggregation/ifNull/
- * @author Mark Paluch
- * @author Christoph Strobl
- * @since 1.10
- */
-public class IfNullOperator implements AggregationExpression {
-
-	private final Field field;
-	private final Object value;
-
-	/**
-	 * Creates a new {@link IfNullOperator} for the given {@link Field} and replacement {@code value}.
-	 *
-	 * @param field must not be {@literal null}.
-	 * @param value must not be {@literal null}.
-	 */
-	public IfNullOperator(Field field, Object value) {
-
-		Assert.notNull(field, "Field must not be null!");
-		Assert.notNull(value, "'Replacement-value' must not be null!");
-
-		this.field = field;
-		this.value = value;
-	}
-
-	/*
-	 * (non-Javadoc)
-	 * @see org.springframework.data.mongodb.core.aggregation.AggregationExpression#toDocument(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
-	 */
-	@Override
-	public Document toDocument(AggregationOperationContext context) {
-
-		List<Object> list = new ArrayList<Object>();
-
-		list.add(context.getReference(field).toString());
-		list.add(resolve(value, context));
-
-		return new Document("$ifNull", list);
-	}
-
-	private Object resolve(Object value, AggregationOperationContext context) {
-
-		if (value instanceof Field) {
-			return context.getReference((Field) value).toString();
-		} else if (value instanceof Document) {
-			return value;
-		}
-
-		return context.getMappedObject(new Document("$set", value)).get("$set");
-	}
-
-	/**
-	 * Get a builder that allows fluent creation of {@link IfNullOperator}.
-	 *
-	 * @return a new {@link IfNullBuilder}.
-	 */
-	public static IfNullBuilder newBuilder() {
-		return IfNullOperatorBuilder.newBuilder();
-	}
-
-	/**
-	 * @since 1.10
-	 */
-	public static interface IfNullBuilder {
-
-		/**
-		 * @param field the field to check for a {@literal null} value, field reference must not be {@literal null}.
-		 * @return the {@link ThenBuilder}
-		 */
-		ThenBuilder ifNull(Field field);
-
-		/**
-		 * @param field the field to check for a {@literal null} value, field name must not be {@literal null} or empty.
-		 * @return the {@link ThenBuilder}
-		 */
-		ThenBuilder ifNull(String field);
-	}
-
-	/**
-	 * @since 1.10
-	 */
-	public static interface ThenBuilder {
-
-		/**
-		 * @param field the field holding the replacement value, must not be {@literal null}.
-		 * @return the {@link IfNullOperator}
-		 */
-		IfNullOperator thenReplaceWith(Field field);
-
-		/**
-		 * @param value the value to be used if the {@code $ifNull }condition evaluates {@literal true}. Can be a
-		 *          {@link Document}, a value that is supported by MongoDB or a value that can be converted to a MongoDB
-		 *          representation but must not be {@literal null}.
-		 * @return the {@link IfNullOperator}
-		 */
-		IfNullOperator thenReplaceWith(Object value);
-	}
-
-	/**
-	 * Builder for fluent {@link IfNullOperator} creation.
-	 *
-	 * @author Mark Paluch
-	 * @since 1.10
-	 */
-	public static final class IfNullOperatorBuilder implements IfNullBuilder, ThenBuilder {
-
-		private Field field;
-
-		private IfNullOperatorBuilder() {}
-
-		/**
-		 * Creates a new builder for {@link IfNullOperator}.
-		 *
-		 * @return never {@literal null}.
-		 */
-		public static IfNullOperatorBuilder newBuilder() {
-			return new IfNullOperatorBuilder();
-		}
-
-		/*
-		 * (non-Javadoc)
-		 * @see org.springframework.data.mongodb.core.aggregation.IfNullOperator.IfNullBuilder#ifNull(org.springframework.data.mongodb.core.aggregation.Field)
-		 */
-		public ThenBuilder ifNull(Field field) {
-
-			Assert.notNull(field, "Field must not be null!");
-
-			this.field = field;
-			return this;
-		}
-
-		/*
-		 * (non-Javadoc)
-		 * @see org.springframework.data.mongodb.core.aggregation.IfNullOperator.IfNullBuilder#ifNull(java.lang.String)
-		 */
-		public ThenBuilder ifNull(String name) {
-
-			Assert.hasText(name, "Field name must not be null or empty!");
-
-			this.field = Fields.field(name);
-			return this;
-		}
-
-		/*
-		 * (non-Javadoc)
-		 * @see org.springframework.data.mongodb.core.aggregation.IfNullOperator.ThenReplaceBuilder#thenReplaceWith(org.springframework.data.mongodb.core.aggregation.Field)
-		 */
-		@Override
-		public IfNullOperator thenReplaceWith(Field replacementField) {
-
-			Assert.notNull(replacementField, "Replacement field must not be null!");
-
-			return new IfNullOperator(this.field, replacementField);
-		}
-
-		/*
-		 * (non-Javadoc)
-		 * @see org.springframework.data.mongodb.core.aggregation.IfNullOperator.ThenReplaceBuilder#thenReplaceWith(java.lang.Object)
-		 */
-		@Override
-		public IfNullOperator thenReplaceWith(Object value) {
-
-			Assert.notNull(value, "'Replacement-value' must not be null!");
-
-			return new IfNullOperator(this.field, value);
-		}
-	}
-}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/InheritingExposedFieldsAggregationOperationContext.java

@@ -13,17 +13,16 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-
 package org.springframework.data.mongodb.core.aggregation;
 
 import org.springframework.data.mongodb.core.aggregation.ExposedFields.FieldReference;
-import org.springframework.util.Assert;
 
 /**
  * {@link ExposedFieldsAggregationOperationContext} that inherits fields from its parent
  * {@link AggregationOperationContext}.
  *
  * @author Mark Paluch
+ * @since 1.9
  */
 class InheritingExposedFieldsAggregationOperationContext extends ExposedFieldsAggregationOperationContext {
 
@@ -40,7 +39,7 @@ class InheritingExposedFieldsAggregationOperationContext extends ExposedFieldsAg
 			AggregationOperationContext previousContext) {
 
 		super(exposedFields, previousContext);
-		Assert.notNull(previousContext, "PreviousContext must not be null!");
+
 		this.previousContext = previousContext;
 	}
 

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/LimitOperation.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2016 the original author or authors.
+ * Copyright 2013-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -15,20 +15,21 @@
  */
 package org.springframework.data.mongodb.core.aggregation;
 
-import org.bson.Document;
 import org.springframework.util.Assert;
 
+import com.mongodb.BasicDBObject;
+import com.mongodb.DBObject;
+
 /**
  * Encapsulates the {@code $limit}-operation.
  * <p>
  * We recommend to use the static factory method {@link Aggregation#limit(long)} instead of creating instances of this
  * class directly.
  * 
- * @see http://docs.mongodb.org/manual/reference/aggregation/limit/
  * @author Thomas Darimont
  * @author Oliver Gierke
- * @author Christoph Strobl
  * @since 1.3
+ * @see <a href="https://docs.mongodb.org/manual/reference/aggregation/limit/">MongoDB Aggregation Framework: $limit</a>
  */
 public class LimitOperation implements AggregationOperation {
 
@@ -45,10 +46,10 @@ public class LimitOperation implements AggregationOperation {
 
 	/* 
 	 * (non-Javadoc)
-	 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperation#toDocument(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
+	 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperation#toDBObject(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
 	 */
 	@Override
-	public Document toDocument(AggregationOperationContext context) {
-		return new Document("$limit", Long.valueOf(maxElements));
+	public DBObject toDBObject(AggregationOperationContext context) {
+		return new BasicDBObject("$limit", maxElements);
 	}
 }

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/LiteralOperators.java

@@ -0,0 +1,96 @@
+/*
+ * Copyright 2016. the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb.core.aggregation;
+
+import org.springframework.util.Assert;
+
+/**
+ * Gateway to {@literal literal} aggregation operations.
+ *
+ * @author Christoph Strobl
+ * @since 1.10
+ */
+public class LiteralOperators {
+
+	/**
+	 * Take the value referenced by given {@literal value}.
+	 *
+	 * @param value must not be {@literal null}.
+	 * @return
+	 */
+	public static LiteralOperatorFactory valueOf(Object value) {
+
+		Assert.notNull(value, "Value must not be null!");
+		return new LiteralOperatorFactory(value);
+	}
+
+	/**
+	 * @author Christoph Strobl
+	 */
+	public static class LiteralOperatorFactory {
+
+		private final Object value;
+
+		/**
+		 * Creates new {@link LiteralOperatorFactory} for given {@literal value}.
+		 *
+		 * @param value must not be {@literal null}.
+		 */
+		public LiteralOperatorFactory(Object value) {
+
+			Assert.notNull(value, "Value must not be null!");
+			this.value = value;
+		}
+
+		/**
+		 * Creates new {@link Literal} that returns the associated value without parsing.
+		 *
+		 * @return
+		 */
+		public Literal asLiteral() {
+			return Literal.asLiteral(value);
+		}
+	}
+
+	/**
+	 * {@link AggregationExpression} for {@code $literal}.
+	 *
+	 * @author Christoph Strobl
+	 */
+	public static class Literal extends AbstractAggregationExpression {
+
+		private Literal(Object value) {
+			super(value);
+		}
+
+		@Override
+		protected String getMongoMethod() {
+			return "$literal";
+		}
+
+		/**
+		 * Creates new {@link Literal}.
+		 *
+		 * @param value must not be {@literal null}.
+		 * @return
+		 */
+		public static Literal asLiteral(Object value) {
+
+			Assert.notNull(value, "Value must not be null!");
+			return new Literal(value);
+		}
+	}
+}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/LookupOperation.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016 the original author or authors.
+ * Copyright 2016-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -15,11 +15,13 @@
  */
 package org.springframework.data.mongodb.core.aggregation;
 
-import org.bson.Document;
 import org.springframework.data.mongodb.core.aggregation.ExposedFields.ExposedField;
 import org.springframework.data.mongodb.core.aggregation.FieldsExposingAggregationOperation.InheritsFieldsAggregationOperation;
 import org.springframework.util.Assert;
 
+import com.mongodb.BasicDBObject;
+import com.mongodb.DBObject;
+
 /**
  * Encapsulates the aggregation framework {@code $lookup}-operation. We recommend to use the static factory method
  * {@link Aggregation#lookup(String, String, String, String)} instead of creating instances of this class directly.
@@ -27,8 +29,8 @@ import org.springframework.util.Assert;
  * @author Alessio Fachechi
  * @author Christoph Strobl
  * @author Mark Paluch
- * @see http://docs.mongodb.org/manual/reference/aggregation/lookup/#stage._S_lookup
  * @since 1.9
+ * @see <a href="https://docs.mongodb.com/manual/reference/operator/aggregation/lookup/">MongoDB Aggregation Framework: $lookup</a>
  */
 public class LookupOperation implements FieldsExposingAggregationOperation, InheritsFieldsAggregationOperation {
 
@@ -73,19 +75,19 @@ public class LookupOperation implements FieldsExposingAggregationOperation, Inhe
 
 	/*
 	 * (non-Javadoc)
-	 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperation#toDocument(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
+	 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperation#toDBObject(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
 	 */
 	@Override
-	public Document toDocument(AggregationOperationContext context) {
+	public DBObject toDBObject(AggregationOperationContext context) {
 
-		Document lookupObject = new Document();
+		BasicDBObject lookupObject = new BasicDBObject();
 
 		lookupObject.append("from", from.getTarget());
 		lookupObject.append("localField", localField.getTarget());
 		lookupObject.append("foreignField", foreignField.getTarget());
 		lookupObject.append("as", as.getTarget());
 
-		return new Document("$lookup", lookupObject);
+		return new BasicDBObject("$lookup", lookupObject);
 	}
 
 	/**

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/MatchOperation.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2015 the original author or authors.
+ * Copyright 2013-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -15,10 +15,12 @@
  */
 package org.springframework.data.mongodb.core.aggregation;
 
-import org.bson.Document;
 import org.springframework.data.mongodb.core.query.CriteriaDefinition;
 import org.springframework.util.Assert;
 
+import com.mongodb.BasicDBObject;
+import com.mongodb.DBObject;
+
 /**
  * Encapsulates the {@code $match}-operation.
  * <p>
@@ -26,11 +28,11 @@ import org.springframework.util.Assert;
  * {@link Aggregation#match(org.springframework.data.mongodb.core.query.Criteria)} instead of creating instances of this
  * class directly.
  * 
- * @see http://docs.mongodb.org/manual/reference/aggregation/match/
  * @author Sebastian Herold
  * @author Thomas Darimont
  * @author Oliver Gierke
  * @since 1.3
+ * @see <a href="https://docs.mongodb.com/manual/reference/operator/aggregation/match/">MongoDB Aggregation Framework: $match</a>
  */
 public class MatchOperation implements AggregationOperation {
 
@@ -49,10 +51,10 @@ public class MatchOperation implements AggregationOperation {
 
 	/* 
 	 * (non-Javadoc)
-	 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperation#toDocument(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
+	 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperation#toDBObject(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
 	 */
 	@Override
-	public Document toDocument(AggregationOperationContext context) {
-		return new Document("$match", context.getMappedObject(criteriaDefinition.getCriteriaObject()));
+	public DBObject toDBObject(AggregationOperationContext context) {
+		return new BasicDBObject("$match", context.getMappedObject(criteriaDefinition.getCriteriaObject()));
 	}
 }

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/NestedDelegatingExpressionAggregationOperationContext.java

@@ -0,0 +1,73 @@
+/*
+ * Copyright 2016. the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb.core.aggregation;
+
+import org.springframework.data.mongodb.core.aggregation.ExposedFields.FieldReference;
+import org.springframework.data.mongodb.core.aggregation.ExposedFields.ExpressionFieldReference;
+import org.springframework.util.Assert;
+
+import com.mongodb.DBObject;
+
+/**
+ * {@link AggregationOperationContext} that delegates {@link FieldReference} resolution and mapping to a parent one, but
+ * assures {@link FieldReference} get converted into {@link ExpressionFieldReference} using {@code $$} to ref an inner
+ * variable.
+ *
+ * @author Christoph Strobl
+ * @since 1.10
+ */
+class NestedDelegatingExpressionAggregationOperationContext implements AggregationOperationContext {
+
+	private final AggregationOperationContext delegate;
+
+	/**
+	 * Creates new {@link NestedDelegatingExpressionAggregationOperationContext}.
+	 *
+	 * @param referenceContext must not be {@literal null}.
+	 */
+	public NestedDelegatingExpressionAggregationOperationContext(AggregationOperationContext referenceContext) {
+
+		Assert.notNull(referenceContext, "Reference context must not be null!");
+		this.delegate = referenceContext;
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperationContext#getMappedObject(com.mongodb.DBObject)
+	 */
+	@Override
+	public DBObject getMappedObject(DBObject dbObject) {
+		return delegate.getMappedObject(dbObject);
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperationContext#getReference(org.springframework.data.mongodb.core.aggregation.Field)
+	 */
+	@Override
+	public FieldReference getReference(Field field) {
+		return new ExpressionFieldReference(delegate.getReference(field));
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperationContext#getReference(java.lang.String)
+	 */
+	@Override
+	public FieldReference getReference(String name) {
+		return new ExpressionFieldReference(delegate.getReference(name));
+	}
+}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/OutOperation.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016 the original author or authors.
+ * Copyright 2016-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -15,7 +15,8 @@
  */
 package org.springframework.data.mongodb.core.aggregation;
 
-import org.bson.Document;
+import com.mongodb.BasicDBObject;
+import com.mongodb.DBObject;
 import org.springframework.util.Assert;
 
 /**
@@ -24,9 +25,8 @@ import org.springframework.util.Assert;
  * We recommend to use the static factory method {@link Aggregation#out(String)} instead of creating instances of this
  * class directly.
  *
- * @see http://docs.mongodb.org/manual/reference/aggregation/out/
  * @author Nikolay Bogdanov
- * @author Christoph Strobl
+ * @see <a href="https://docs.mongodb.com/manual/reference/operator/aggregation/out/">MongoDB Aggregation Framework: $out</a>
  */
 public class OutOperation implements AggregationOperation {
 
@@ -42,10 +42,10 @@ public class OutOperation implements AggregationOperation {
 
 	/*
 	 * (non-Javadoc)
-	 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperation#toDocument(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
+	 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperation#toDBObject(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
 	 */
 	@Override
-	public Document toDocument(AggregationOperationContext context) {
-		return new Document("$out", collectionName);
+	public DBObject toDBObject(AggregationOperationContext context) {
+		return new BasicDBObject("$out", collectionName);
 	}
 }

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/ProjectionOperation.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2016 the original author or authors.
+ * Copyright 2013-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,15 +17,21 @@ package org.springframework.data.mongodb.core.aggregation;
 
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
 
-import org.bson.Document;
+import org.springframework.data.mongodb.core.aggregation.ConditionalOperators.Cond;
+import org.springframework.data.mongodb.core.aggregation.ConditionalOperators.IfNull;
 import org.springframework.data.mongodb.core.aggregation.ExposedFields.ExposedField;
 import org.springframework.data.mongodb.core.aggregation.Fields.AggregationField;
 import org.springframework.data.mongodb.core.aggregation.ProjectionOperation.ProjectionOperationBuilder.FieldProjection;
+import org.springframework.data.mongodb.core.aggregation.VariableOperators.Let.ExpressionVariable;
 import org.springframework.util.Assert;
 
+import com.mongodb.BasicDBObject;
+import com.mongodb.DBObject;
+
 /**
  * Encapsulates the aggregation framework {@code $project}-operation.
  * <p>
@@ -35,13 +41,13 @@ import org.springframework.util.Assert;
  * We recommend to use the static factory method {@link Aggregation#project(Fields)} instead of creating instances of
  * this class directly.
  * 
- * @see http://docs.mongodb.org/manual/reference/aggregation/project/
  * @author Tobias Trelle
  * @author Thomas Darimont
  * @author Oliver Gierke
  * @author Christoph Strobl
  * @author Mark Paluch
  * @since 1.3
+ * @see <a href="https://docs.mongodb.com/manual/reference/operator/aggregation/project/">MongoDB Aggregation Framework: $project</a>
  */
 public class ProjectionOperation implements FieldsExposingAggregationOperation {
 
@@ -184,18 +190,18 @@ public class ProjectionOperation implements FieldsExposingAggregationOperation {
 
 	/*
 	 * (non-Javadoc)
-	 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperation#toDocument(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
+	 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperation#toDBObject(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
 	 */
 	@Override
-	public Document toDocument(AggregationOperationContext context) {
+	public DBObject toDBObject(AggregationOperationContext context) {
 
-		Document fieldObject = new Document();
+		BasicDBObject fieldObject = new BasicDBObject();
 
 		for (Projection projection : projections) {
-			fieldObject.putAll(projection.toDocument(context));
+			fieldObject.putAll(projection.toDBObject(context));
 		}
 
-		return new Document("$project", fieldObject);
+		return new BasicDBObject("$project", fieldObject);
 	}
 
 	/**
@@ -225,11 +231,11 @@ public class ProjectionOperation implements FieldsExposingAggregationOperation {
 
 		/* 
 		 * (non-Javadoc)
-		 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperation#toDocument(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
+		 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperation#toDBObject(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
 		 */
 		@Override
-		public Document toDocument(AggregationOperationContext context) {
-			return this.operation.toDocument(context);
+		public DBObject toDBObject(AggregationOperationContext context) {
+			return this.operation.toDBObject(context);
 		}
 
 		/**
@@ -241,22 +247,22 @@ public class ProjectionOperation implements FieldsExposingAggregationOperation {
 		public abstract ProjectionOperation as(String alias);
 
 		/**
-		 * Apply a conditional projection using {@link ConditionalOperator}.
+		 * Apply a conditional projection using {@link Cond}.
 		 *
-		 * @param conditionalOperator must not be {@literal null}.
+		 * @param cond must not be {@literal null}.
 		 * @return never {@literal null}.
 		 * @since 1.10
 		 */
-		public abstract ProjectionOperation applyCondition(ConditionalOperator conditionalOperator);
+		public abstract ProjectionOperation applyCondition(Cond cond);
 
 		/**
-		 * Apply a conditional value replacement for {@literal null} values using {@link IfNullOperator}.
+		 * Apply a conditional value replacement for {@literal null} values using {@link IfNull}.
 		 *
-		 * @param ifNullOperator must not be {@literal null}.
+		 * @param ifNull must not be {@literal null}.
 		 * @return never {@literal null}.
 		 * @since 1.10
 		 */
-		public abstract ProjectionOperation applyCondition(IfNullOperator ifNullOperator);
+		public abstract ProjectionOperation applyCondition(IfNull ifNull);
 	}
 
 	/**
@@ -351,11 +357,11 @@ public class ProjectionOperation implements FieldsExposingAggregationOperation {
 
 			/* 
 			 * (non-Javadoc)
-			 * @see org.springframework.data.mongodb.core.aggregation.ProjectionOperation.Projection#toDocument(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
+			 * @see org.springframework.data.mongodb.core.aggregation.ProjectionOperation.Projection#toDBObject(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
 			 */
 			@Override
-			public Document toDocument(AggregationOperationContext context) {
-				return new Document(getExposedField().getName(), toMongoExpression(context, expression, params));
+			public DBObject toDBObject(AggregationOperationContext context) {
+				return new BasicDBObject(getExposedField().getName(), toMongoExpression(context, expression, params));
 			}
 
 			protected static Object toMongoExpression(AggregationOperationContext context, String expression,
@@ -460,10 +466,10 @@ public class ProjectionOperation implements FieldsExposingAggregationOperation {
 		 * @see org.springframework.data.mongodb.core.aggregation.ProjectionOperation.AbstractProjectionOperationBuilder#transform(org.springframework.data.mongodb.core.aggregation.ConditionalOperator)
 		 */
 		@Override
-		public ProjectionOperation applyCondition(ConditionalOperator conditionalOperator) {
+		public ProjectionOperation applyCondition(Cond cond) {
 
-			Assert.notNull(conditionalOperator, "ConditionalOperator must not be null!");
-			return this.operation.and(new ExpressionProjection(Fields.field(name), conditionalOperator));
+			Assert.notNull(cond, "ConditionalOperator must not be null!");
+			return this.operation.and(new ExpressionProjection(Fields.field(name), cond));
 		}
 
 		/*
@@ -471,10 +477,10 @@ public class ProjectionOperation implements FieldsExposingAggregationOperation {
 		 * @see org.springframework.data.mongodb.core.aggregation.ProjectionOperation.AbstractProjectionOperationBuilder#transform(org.springframework.data.mongodb.core.aggregation.IfNullOperator)
 		 */
 		@Override
-		public ProjectionOperation applyCondition(IfNullOperator ifNullOperator) {
+		public ProjectionOperation applyCondition(IfNull ifNull) {
 
-			Assert.notNull(ifNullOperator, "IfNullOperator must not be null!");
-			return this.operation.and(new ExpressionProjection(Fields.field(name), ifNullOperator));
+			Assert.notNull(ifNull, "IfNullOperator must not be null!");
+			return this.operation.and(new ExpressionProjection(Fields.field(name), ifNull));
 		}
 
 		/**
@@ -526,6 +532,20 @@ public class ProjectionOperation implements FieldsExposingAggregationOperation {
 			return project("subtract", Fields.field(fieldReference));
 		}
 
+		/**
+		 * Generates an {@code $subtract} expression that subtracts the result of the given {@link AggregationExpression}
+		 * from the previously mentioned field.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder minus(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return project("subtract", expression);
+		}
+
 		/**
 		 * Generates an {@code $multiply} expression that multiplies the given number with the previously mentioned field.
 		 * 
@@ -551,6 +571,20 @@ public class ProjectionOperation implements FieldsExposingAggregationOperation {
 			return project("multiply", Fields.field(fieldReference));
 		}
 
+		/**
+		 * Generates an {@code $multiply} expression that multiplies the previously with the result of the
+		 * {@link AggregationExpression}. mentioned field.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder multiply(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return project("multiply", expression);
+		}
+
 		/**
 		 * Generates an {@code $divide} expression that divides the previously mentioned field by the given number.
 		 * 
@@ -577,6 +611,20 @@ public class ProjectionOperation implements FieldsExposingAggregationOperation {
 			return project("divide", Fields.field(fieldReference));
 		}
 
+		/**
+		 * Generates an {@code $divide} expression that divides the value of the previously mentioned by the result of the
+		 * {@link AggregationExpression}.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder divide(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return project("divide", expression);
+		}
+
 		/**
 		 * Generates an {@code $mod} expression that divides the previously mentioned field by the given number and returns
 		 * the remainder.
@@ -594,7 +642,7 @@ public class ProjectionOperation implements FieldsExposingAggregationOperation {
 		/**
 		 * Generates an {@code $mod} expression that divides the value of the given field by the previously mentioned field
 		 * and returns the remainder.
-		 * 
+		 *
 		 * @param fieldReference
 		 * @return
 		 */
@@ -604,6 +652,20 @@ public class ProjectionOperation implements FieldsExposingAggregationOperation {
 			return project("mod", Fields.field(fieldReference));
 		}
 
+		/**
+		 * Generates an {@code $mod} expression that divides the value of the previously mentioned field by the result of
+		 * the {@link AggregationExpression}.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder mod(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null!");
+			return project("mod", expression);
+		}
+
 		/**
 		 * Generates a {@code $size} expression that returns the size of the array held by the given field. <br />
 		 *
@@ -614,6 +676,85 @@ public class ProjectionOperation implements FieldsExposingAggregationOperation {
 			return project("size");
 		}
 
+		/**
+		 * Generates a {@code $cmp} expression (compare to) that compares the value of the field to a given value or field.
+		 *
+		 * @param compareValue compare value or a {@link Field} object.
+		 * @return never {@literal null}.
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder cmp(Object compareValue) {
+			return project("cmp", compareValue);
+		}
+
+		/**
+		 * Generates a {@code $eq} expression (equal) that compares the value of the field to a given value or field.
+		 *
+		 * @param compareValue compare value or a {@link Field} object.
+		 * @return never {@literal null}.
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder eq(Object compareValue) {
+			return project("eq", compareValue);
+		}
+
+		/**
+		 * Generates a {@code $gt} expression (greater than) that compares the value of the field to a given value or field.
+		 *
+		 * @param compareValue compare value or a {@link Field} object.
+		 * @return never {@literal null}.
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder gt(Object compareValue) {
+			return project("gt", compareValue);
+		}
+
+		/**
+		 * Generates a {@code $gte} expression (greater than equal) that compares the value of the field to a given value or
+		 * field.
+		 *
+		 * @param compareValue compare value or a {@link Field} object.
+		 * @return never {@literal null}.
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder gte(Object compareValue) {
+			return project("gte", compareValue);
+		}
+
+		/**
+		 * Generates a {@code $lt} expression (less than) that compares the value of the field to a given value or field.
+		 *
+		 * @param compareValue compare value or a {@link Field} object.
+		 * @return never {@literal null}.
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder lt(Object compareValue) {
+			return project("lt", compareValue);
+		}
+
+		/**
+		 * Generates a {@code $lte} expression (less than equal) that compares the value of the field to a given value or
+		 * field.
+		 *
+		 * @param compareValue the compare value or a {@link Field} object.
+		 * @return never {@literal null}.
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder lte(Object compareValue) {
+			return project("lte", compareValue);
+		}
+
+		/**
+		 * Generates a {@code $ne} expression (not equal) that compares the value of the field to a given value or field.
+		 *
+		 * @param compareValue compare value or a {@link Field} object.
+		 * @return never {@literal null}.
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder ne(Object compareValue) {
+			return project("ne", compareValue);
+		}
+
 		/**
 		 * Generates a {@code $slice} expression that returns a subset of the array held by the given field. <br />
 		 * If {@literal n} is positive, $slice returns up to the first n elements in the array. <br />
@@ -639,13 +780,459 @@ public class ProjectionOperation implements FieldsExposingAggregationOperation {
 			return project("slice", offset, count);
 		}
 
-		/* 
+		/**
+		 * Generates a {@code $filter} expression that returns a subset of the array held by the given field.
+		 *
+		 * @param as The variable name for the element in the input array. Must not be {@literal null}.
+		 * @param condition The {@link AggregationExpression} that determines whether to include the element in the
+		 *          resulting array. Must not be {@literal null}.
+		 * @return never {@literal null}.
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder filter(String as, AggregationExpression condition) {
+			return this.operation.and(ArrayOperators.Filter.filter(name).as(as).by(condition));
+		}
+
+		// SET OPERATORS
+
+		/**
+		 * Generates a {@code $setEquals} expression that compares the previously mentioned field to one or more arrays and
+		 * returns {@literal true} if they have the same distinct elements and {@literal false} otherwise.
+		 *
+		 * @param arrays must not be {@literal null}.
+		 * @return never {@literal null}.
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder equalsArrays(String... arrays) {
+
+			Assert.notEmpty(arrays, "Arrays must not be null or empty!");
+			return project("setEquals", Fields.fields(arrays));
+		}
+
+		/**
+		 * Generates a {@code $setIntersection} expression that takes array of the previously mentioned field and one or
+		 * more arrays and returns an array that contains the elements that appear in every of those.
+		 *
+		 * @param arrays must not be {@literal null}.
+		 * @return never {@literal null}.
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder intersectsArrays(String... arrays) {
+
+			Assert.notEmpty(arrays, "Arrays must not be null or empty!");
+			return project("setIntersection", Fields.fields(arrays));
+		}
+
+		/**
+		 * Generates a {@code $setUnion} expression that takes array of the previously mentioned field and one or more
+		 * arrays and returns an array that contains the elements that appear in any of those.
+		 *
+		 * @param arrays must not be {@literal null}.
+		 * @return never {@literal null}.
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder unionArrays(String... arrays) {
+
+			Assert.notEmpty(arrays, "Arrays must not be null or empty!");
+			return project("setUnion", Fields.fields(arrays));
+		}
+
+		/**
+		 * Generates a {@code $setDifference} expression that takes array of the previously mentioned field and returns an
+		 * array containing the elements that do not exist in the given {@literal array}.
+		 *
+		 * @param array must not be {@literal null}.
+		 * @return never {@literal null}.
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder differenceToArray(String array) {
+
+			Assert.hasText(array, "Array must not be null or empty!");
+			return project("setDifference", Fields.fields(array));
+		}
+
+		/**
+		 * Generates a {@code $setIsSubset} expression that takes array of the previously mentioned field and returns
+		 * {@literal true} if it is a subset of the given {@literal array}.
+		 *
+		 * @param array must not be {@literal null}.
+		 * @return never {@literal null}.
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder subsetOfArray(String array) {
+
+			Assert.hasText(array, "Array must not be null or empty!");
+			return project("setIsSubset", Fields.fields(array));
+		}
+
+		/**
+		 * Generates an {@code $anyElementTrue} expression that Takes array of the previously mentioned field and returns
+		 * {@literal true} if any of the elements are {@literal true} and {@literal false} otherwise.
+		 *
+		 * @return never {@literal null}.
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder anyElementInArrayTrue() {
+			return project("anyElementTrue");
+		}
+
+		/**
+		 * Generates an {@code $allElementsTrue} expression that takes array of the previously mentioned field and returns
+		 * {@literal true} if no elements is {@literal false}.
+		 *
+		 * @return never {@literal null}.
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder allElementsInArrayTrue() {
+			return project("allElementsTrue");
+		}
+
+		/**
+		 * Generates a {@code $abs} expression that takes the number of the previously mentioned field and returns the
+		 * absolute value of it.
+		 *
+		 * @return never {@literal null}.
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder absoluteValue() {
+			return this.operation.and(ArithmeticOperators.Abs.absoluteValueOf(name));
+		}
+
+		/**
+		 * Generates a {@code $ceil} expression that takes the number of the previously mentioned field and returns the
+		 * smallest integer greater than or equal to the specified number.
+		 *
+		 * @return never {@literal null}.
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder ceil() {
+			return this.operation.and(ArithmeticOperators.Ceil.ceilValueOf(name));
+		}
+
+		/**
+		 * Generates a {@code $exp} expression that takes the number of the previously mentioned field and raises Euler’s
+		 * number (i.e. e ) on it.
+		 *
+		 * @return never {@literal null}.
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder exp() {
+			return this.operation.and(ArithmeticOperators.Exp.expValueOf(name));
+		}
+
+		/**
+		 * Generates a {@code $floor} expression that takes the number of the previously mentioned field and returns the
+		 * largest integer less than or equal to it.
+		 *
+		 * @return never {@literal null}.
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder floor() {
+			return this.operation.and(ArithmeticOperators.Floor.floorValueOf(name));
+		}
+
+		/**
+		 * Generates a {@code $ln} expression that takes the number of the previously mentioned field and calculates the
+		 * natural logarithm ln (i.e loge) of it.
+		 *
+		 * @return never {@literal null}.
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder ln() {
+			return this.operation.and(ArithmeticOperators.Ln.lnValueOf(name));
+		}
+
+		/**
+		 * Generates a {@code $log} expression that takes the number of the previously mentioned field and calculates the
+		 * log of the associated number in the specified base.
+		 *
+		 * @param baseFieldRef must not be {@literal null}.
+		 * @return never {@literal null}.
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder log(String baseFieldRef) {
+			return this.operation.and(ArithmeticOperators.Log.valueOf(name).log(baseFieldRef));
+		}
+
+		/**
+		 * Generates a {@code $log} expression that takes the number of the previously mentioned field and calculates the
+		 * log of the associated number in the specified base.
+		 *
+		 * @param base must not be {@literal null}.
+		 * @return never {@literal null}.
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder log(Number base) {
+			return this.operation.and(ArithmeticOperators.Log.valueOf(name).log(base));
+		}
+
+		/**
+		 * Generates a {@code $log} expression that takes the number of the previously mentioned field and calculates the
+		 * log of the associated number in the specified base.
+		 *
+		 * @param base must not be {@literal null}.
+		 * @return never {@literal null}.
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder log(AggregationExpression base) {
+			return this.operation.and(ArithmeticOperators.Log.valueOf(name).log(base));
+		}
+
+		/**
+		 * Generates a {@code $log10} expression that takes the number of the previously mentioned field and calculates the
+		 * log base 10.
+		 *
+		 * @return never {@literal null}.
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder log10() {
+			return this.operation.and(ArithmeticOperators.Log10.log10ValueOf(name));
+		}
+
+		/**
+		 * Generates a {@code $pow} expression that takes the number of the previously mentioned field and raises it by the
+		 * specified exponent.
+		 *
+		 * @param exponentFieldRef must not be {@literal null}.
+		 * @return never {@literal null}.
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder pow(String exponentFieldRef) {
+			return this.operation.and(ArithmeticOperators.Pow.valueOf(name).pow(exponentFieldRef));
+		}
+
+		/**
+		 * Generates a {@code $pow} expression that takes the number of the previously mentioned field and raises it by the
+		 * specified exponent.
+		 *
+		 * @param exponent must not be {@literal null}.
+		 * @return never {@literal null}.
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder pow(Number exponent) {
+			return this.operation.and(ArithmeticOperators.Pow.valueOf(name).pow(exponent));
+		}
+
+		/**
+		 * Generates a {@code $pow} expression that Takes the number of the previously mentioned field and raises it by the
+		 * specified exponent.
+		 *
+		 * @param exponentExpression must not be {@literal null}.
+		 * @return never {@literal null}.
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder pow(AggregationExpression exponentExpression) {
+			return this.operation.and(ArithmeticOperators.Pow.valueOf(name).pow(exponentExpression));
+		}
+
+		/**
+		 * Generates a {@code $sqrt} expression that takes the number of the previously mentioned field and calculates the
+		 * square root.
+		 *
+		 * @return never {@literal null}.
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder sqrt() {
+			return this.operation.and(ArithmeticOperators.Sqrt.sqrtOf(name));
+		}
+
+		/**
+		 * Takes the number of the previously mentioned field and truncates it to its integer value.
+		 *
+		 * @return never {@literal null}.
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder trunc() {
+			return this.operation.and(ArithmeticOperators.Trunc.truncValueOf(name));
+		}
+
+		/**
+		 * Generates a {@code $concat} expression that takes the string representation of the previously mentioned field and
+		 * concats given values to it.
+		 *
+		 * @return never {@literal null}.
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder concat(Object... values) {
+			return project("concat", values);
+		}
+
+		/**
+		 * Generates a {@code $substr} expression that Takes the string representation of the previously mentioned field and
+		 * returns a substring starting at a specified index position.
+		 *
+		 * @param start
+		 * @return
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder substring(int start) {
+			return substring(start, -1);
+		}
+
+		/**
+		 * Generates a {@code $substr} expression that takes the string representation of the previously mentioned field and
+		 * returns a substring starting at a specified index position including the specified number of characters.
+		 *
+		 * @param start
+		 * @param nrOfChars
+		 * @return
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder substring(int start, int nrOfChars) {
+			return project("substr", start, nrOfChars);
+		}
+
+		/**
+		 * Generates a {@code $toLower} expression that takes the string representation of the previously mentioned field
+		 * and lowers it.
+		 *
+		 * @return
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder toLower() {
+			return this.operation.and(StringOperators.ToLower.lowerValueOf(name));
+		}
+
+		/**
+		 * Generates a {@code $toUpper} expression that takes the string representation of the previously mentioned field
+		 * and uppers it.
+		 *
+		 * @return
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder toUpper() {
+			return this.operation.and(StringOperators.ToUpper.upperValueOf(name));
+		}
+
+		/**
+		 * Generates a {@code $strcasecmp} expression that takes the string representation of the previously mentioned field
+		 * and performs case-insensitive comparison to the given {@literal value}.
+		 *
+		 * @param value must not be {@literal null}.
+		 * @return
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder strCaseCmp(String value) {
+			return project("strcasecmp", value);
+		}
+
+		/**
+		 * Generates a {@code $strcasecmp} expression that takes the string representation of the previously mentioned field
+		 * and performs case-insensitive comparison to the referenced {@literal fieldRef}.
+		 *
+		 * @param fieldRef must not be {@literal null}.
+		 * @return
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder strCaseCmpValueOf(String fieldRef) {
+			return project("strcasecmp", fieldRef);
+		}
+
+		/**
+		 * Generates a {@code $strcasecmp} expression that takes the string representation of the previously mentioned field
+		 * and performs case-insensitive comparison to the result of the given {@link AggregationExpression}.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder strCaseCmp(AggregationExpression expression) {
+			return project("strcasecmp", expression);
+		}
+
+		/**
+		 * Generates a {@code $arrayElemAt} expression that takes the string representation of the previously mentioned
+		 * field and returns the element at the specified array {@literal position}.
+		 *
+		 * @param position
+		 * @return
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder arrayElementAt(int position) {
+			return project("arrayElemAt", position);
+		}
+
+		/**
+		 * Generates a {@code $concatArrays} expression that takes the string representation of the previously mentioned
+		 * field and concats it with the arrays from the referenced {@literal fields}.
+		 *
+		 * @param fields must not be {@literal null}.
+		 * @return
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder concatArrays(String... fields) {
+			return project("concatArrays", Fields.fields(fields));
+		}
+
+		/**
+		 * Generates a {@code $isArray} expression that takes the string representation of the previously mentioned field
+		 * and checks if its an array.
+		 *
+		 * @return
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder isArray() {
+			return this.operation.and(ArrayOperators.IsArray.isArray(name));
+		}
+
+		/**
+		 * Generates a {@code $literal} expression that Takes the value previously and uses it as literal.
+		 *
+		 * @return
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder asLiteral() {
+			return this.operation.and(LiteralOperators.Literal.asLiteral(name));
+		}
+
+		/**
+		 * Generates a {@code $dateToString} expression that takes the date representation of the previously mentioned field
+		 * and applies given {@literal format} to it.
+		 *
+		 * @param format must not be {@literal null}.
+		 * @return
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder dateAsFormattedString(String format) {
+			return this.operation.and(DateOperators.DateToString.dateOf(name).toString(format));
+		}
+
+		/**
+		 * Generates a {@code $let} expression that binds variables for use in the specified expression, and returns the
+		 * result of the expression.
+		 *
+		 * @param valueExpression The {@link AggregationExpression} bound to {@literal variableName}.
+		 * @param variableName The variable name to be used in the {@literal in} {@link AggregationExpression}.
+		 * @param in The {@link AggregationExpression} to evaluate.
+		 * @return never {@literal null}.
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder let(AggregationExpression valueExpression, String variableName,
+				AggregationExpression in) {
+			return this.operation.and(VariableOperators.Let
+					.define(ExpressionVariable.newVariable(variableName).forExpression(valueExpression)).andApply(in));
+		}
+
+		/**
+		 * Generates a {@code $let} expression that binds variables for use in the specified expression, and returns the
+		 * result of the expression.
+		 *
+		 * @param variables The bound {@link ExpressionVariable}s.
+		 * @param in The {@link AggregationExpression} to evaluate.
+		 * @return never {@literal null}.
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder let(Collection<ExpressionVariable> variables, AggregationExpression in) {
+			return this.operation.and(VariableOperators.Let.define(variables).andApply(in));
+		}
+
+		/*
 		 * (non-Javadoc)
-		 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperation#toDocument(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
+		 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperation#toDBObject(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
 		 */
 		@Override
-		public Document toDocument(AggregationOperationContext context) {
-			return this.operation.toDocument(context);
+		public DBObject toDBObject(AggregationOperationContext context) {
+			return this.operation.toDBObject(context);
 		}
 
 		/**
@@ -682,11 +1269,11 @@ public class ProjectionOperation implements FieldsExposingAggregationOperation {
 
 			/* 
 			 * (non-Javadoc)
-			 * @see org.springframework.data.mongodb.core.aggregation.ProjectionOperation.Projection#toDocument(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
+			 * @see org.springframework.data.mongodb.core.aggregation.ProjectionOperation.Projection#toDBObject(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
 			 */
 			@Override
-			public Document toDocument(AggregationOperationContext context) {
-				return new Document(name, Fields.UNDERSCORE_ID_REF);
+			public DBObject toDBObject(AggregationOperationContext context) {
+				return new BasicDBObject(name, Fields.UNDERSCORE_ID_REF);
 			}
 		}
 
@@ -695,6 +1282,7 @@ public class ProjectionOperation implements FieldsExposingAggregationOperation {
 		 * 
 		 * @author Oliver Gierke
 		 * @author Thomas Darimont
+		 * @author Mark Paluch
 		 */
 		static class FieldProjection extends Projection {
 
@@ -713,7 +1301,7 @@ public class ProjectionOperation implements FieldsExposingAggregationOperation {
 
 			private FieldProjection(Field field, Object value) {
 
-				super(field);
+				super(new ExposedField(field.getName(), true));
 
 				this.field = field;
 				this.value = value;
@@ -751,11 +1339,11 @@ public class ProjectionOperation implements FieldsExposingAggregationOperation {
 
 			/* 
 			 * (non-Javadoc)
-			 * @see org.springframework.data.mongodb.core.aggregation.ProjectionOperation.Projection#toDocument(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
+			 * @see org.springframework.data.mongodb.core.aggregation.ProjectionOperation.Projection#toDBObject(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
 			 */
 			@Override
-			public Document toDocument(AggregationOperationContext context) {
-				return new Document(field.getName(), renderFieldValue(context));
+			public DBObject toDBObject(AggregationOperationContext context) {
+				return new BasicDBObject(field.getName(), renderFieldValue(context));
 			}
 
 			private Object renderFieldValue(AggregationOperationContext context) {
@@ -807,14 +1395,14 @@ public class ProjectionOperation implements FieldsExposingAggregationOperation {
 
 			/*
 			 * (non-Javadoc)
-			 * @see org.springframework.data.mongodb.core.aggregation.ProjectionOperation.Projection#toDocument(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
+			 * @see org.springframework.data.mongodb.core.aggregation.ProjectionOperation.Projection#toDBObject(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
 			 */
 			@Override
-			public Document toDocument(AggregationOperationContext context) {
+			public DBObject toDBObject(AggregationOperationContext context) {
 
-				Document inner = new Document("$" + operation, getOperationArguments(context));
+				DBObject inner = new BasicDBObject("$" + operation, getOperationArguments(context));
 
-				return new Document(getField().getName(), inner);
+				return new BasicDBObject(getField().getName(), inner);
 			}
 
 			protected List<Object> getOperationArguments(AggregationOperationContext context) {
@@ -823,7 +1411,18 @@ public class ProjectionOperation implements FieldsExposingAggregationOperation {
 				result.add(context.getReference(getField().getName()).toString());
 
 				for (Object element : values) {
-					result.add(element instanceof Field ? context.getReference((Field) element).toString() : element);
+
+					if (element instanceof Field) {
+						result.add(context.getReference((Field) element).toString());
+					} else if (element instanceof Fields) {
+						for (Field field : (Fields) element) {
+							result.add(context.getReference(field).toString());
+						}
+					} else if (element instanceof AggregationExpression) {
+						result.add(((AggregationExpression) element).toDbObject(context));
+					} else {
+						result.add(element);
+					}
 				}
 
 				return result;
@@ -897,18 +1496,18 @@ public class ProjectionOperation implements FieldsExposingAggregationOperation {
 
 			/* 
 			 * (non-Javadoc)
-			 * @see org.springframework.data.mongodb.core.aggregation.ProjectionOperation.Projection#toDocument(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
+			 * @see org.springframework.data.mongodb.core.aggregation.ProjectionOperation.Projection#toDBObject(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
 			 */
 			@Override
-			public Document toDocument(AggregationOperationContext context) {
+			public DBObject toDBObject(AggregationOperationContext context) {
 
-				Document nestedObject = new Document();
+				DBObject nestedObject = new BasicDBObject();
 
 				for (Field field : fields) {
 					nestedObject.put(field.getName(), context.getReference(field.getTarget()).toString());
 				}
 
-				return new Document(name, nestedObject);
+				return new BasicDBObject(name, nestedObject);
 			}
 		}
 
@@ -1033,13 +1632,13 @@ public class ProjectionOperation implements FieldsExposingAggregationOperation {
 		}
 
 		/**
-		 * Renders the current {@link Projection} into a {@link Document} based on the given
+		 * Renders the current {@link Projection} into a {@link DBObject} based on the given
 		 * {@link AggregationOperationContext}.
 		 * 
 		 * @param context will never be {@literal null}.
 		 * @return
 		 */
-		public abstract Document toDocument(AggregationOperationContext context);
+		public abstract DBObject toDBObject(AggregationOperationContext context);
 	}
 
 	/**
@@ -1064,8 +1663,8 @@ public class ProjectionOperation implements FieldsExposingAggregationOperation {
 		}
 
 		@Override
-		public Document toDocument(AggregationOperationContext context) {
-			return new Document(field.getName(), expression.toDocument(context));
+		public DBObject toDBObject(AggregationOperationContext context) {
+			return new BasicDBObject(field.getName(), expression.toDbObject(context));
 		}
 	}
 }