DATAMONGO-799 - Release version 1.4.0.M1.

Updated project metadata and bumped versions.

README.md

@@ -6,7 +6,7 @@ The Spring Data MongoDB project aims to provide a familiar and consistent Spring
 
 ## Getting Help
 
-For a comprehensive treatmet of all the Spring Data MongoDB features, please refer to:
+For a comprehensive treatment of all the Spring Data MongoDB features, please refer to:
 
 * the [User Guide](http://static.springsource.org/spring-data/data-mongodb/docs/current/reference/html/) 
 * the [JavaDocs](http://static.springsource.org/spring-data/data-mongodb/docs/current/api/) have extensive comments in them as well.
@@ -26,7 +26,7 @@ Add the Maven dependency:
 <dependency>
   <groupId>org.springframework.data</groupId>
   <artifactId>spring-data-mongodb</artifactId>
-  <version>1.2.1.RELEASE</version>
+  <version>1.3.2.RELEASE</version>
 </dependency>
 ```
 
@@ -36,7 +36,7 @@ If you'd rather like the latest snapshots of the upcoming major version, use our
 <dependency>
   <groupId>org.springframework.data</groupId>
   <artifactId>spring-data-mongodb</artifactId>
-  <version>1.2.1.RELEASE</version>
+  <version>1.4.0.BUILD-SNAPSHOT</version>
 </dependency>
 
 <repository>
@@ -57,7 +57,7 @@ MongoTemplate is the central support class for Mongo database operations. It pro
 
 ### Spring Data repositories
 
-To simplify the creation of data repositories Sprin Data MongoDB provides a generic repository programming model. It will automatically create a repository proxy for you that adds implementations of finder methods you specify on an interface.  
+To simplify the creation of data repositories Spring Data MongoDB provides a generic repository programming model. It will automatically create a repository proxy for you that adds implementations of finder methods you specify on an interface.  
 
 For example, given a `Person` class with first and last name properties, a `PersonRepository` interface that can query for `Person` by last name and when the first name matches a like expression is shown below:
 
@@ -70,7 +70,7 @@ public interface PersonRepository extends CrudRepository<Person, Long> {
 }
 ```
 
-The queries issued on execution will be derived from the method name. Exending `CrudRepository` causes CRUD methods being pulled into the interface so that you can easily save and find single entities and collections of them.
+The queries issued on execution will be derived from the method name. Extending `CrudRepository` causes CRUD methods being pulled into the interface so that you can easily save and find single entities and collections of them.
 
 You can have Spring automatically create a proxy for the interface by using the following JavaConfig:
 

etc/formatting.xml

@@ -73,7 +73,7 @@
 <setting id="org.eclipse.jdt.core.formatter.insert_space_before_opening_brace_in_enum_declaration" value="insert"/>
 <setting id="org.eclipse.jdt.core.formatter.insert_space_before_opening_angle_bracket_in_type_parameters" value="do not insert"/>
 <setting id="org.eclipse.jdt.core.formatter.comment.clear_blank_lines_in_block_comment" value="false"/>
-<setting id="org.eclipse.jdt.core.formatter.insert_new_line_in_empty_type_declaration" value="insert"/>
+<setting id="org.eclipse.jdt.core.formatter.insert_new_line_in_empty_type_declaration" value="do not insert"/>
 <setting id="org.eclipse.jdt.core.formatter.lineSplit" value="120"/>
 <setting id="org.eclipse.jdt.core.formatter.insert_space_before_opening_paren_in_if" value="insert"/>
 <setting id="org.eclipse.jdt.core.formatter.insert_space_between_brackets_in_array_type_reference" value="do not insert"/>
@@ -102,7 +102,7 @@
 <setting id="org.eclipse.jdt.core.formatter.alignment_for_parameters_in_constructor_declaration" value="16"/>
 <setting id="org.eclipse.jdt.core.formatter.insert_space_after_colon_in_labeled_statement" value="insert"/>
 <setting id="org.eclipse.jdt.core.formatter.brace_position_for_annotation_type_declaration" value="end_of_line"/>
-<setting id="org.eclipse.jdt.core.formatter.insert_new_line_in_empty_method_body" value="insert"/>
+<setting id="org.eclipse.jdt.core.formatter.insert_new_line_in_empty_method_body" value="do not insert"/>
 <setting id="org.eclipse.jdt.core.formatter.alignment_for_method_declaration" value="0"/>
 <setting id="org.eclipse.jdt.core.formatter.insert_space_before_closing_paren_in_method_invocation" value="do not insert"/>
 <setting id="org.eclipse.jdt.core.formatter.insert_space_before_closing_paren_in_try" value="do not insert"/>
@@ -124,7 +124,7 @@
 <setting id="org.eclipse.jdt.core.formatter.insert_space_before_parenthesized_expression_in_throw" value="insert"/>
 <setting id="org.eclipse.jdt.core.formatter.insert_space_before_comma_in_type_arguments" value="do not insert"/>
 <setting id="org.eclipse.jdt.core.compiler.problem.enumIdentifier" value="error"/>
-<setting id="org.eclipse.jdt.core.formatter.indent_switchstatements_compare_to_switch" value="false"/>
+<setting id="org.eclipse.jdt.core.formatter.indent_switchstatements_compare_to_switch" value="true"/>
 <setting id="org.eclipse.jdt.core.formatter.insert_space_before_ellipsis" value="do not insert"/>
 <setting id="org.eclipse.jdt.core.formatter.brace_position_for_block" value="end_of_line"/>
 <setting id="org.eclipse.jdt.core.formatter.insert_space_before_comma_in_for_inits" value="do not insert"/>
@@ -135,9 +135,9 @@
 <setting id="org.eclipse.jdt.core.formatter.insert_space_after_comma_in_for_increments" value="insert"/>
 <setting id="org.eclipse.jdt.core.formatter.format_line_comment_starting_on_first_column" value="true"/>
 <setting id="org.eclipse.jdt.core.formatter.insert_space_before_closing_bracket_in_array_reference" value="do not insert"/>
-<setting id="org.eclipse.jdt.core.formatter.insert_new_line_after_annotation_on_field" value="insert"/>
-<setting id="org.eclipse.jdt.core.formatter.brace_position_for_enum_constant" value="end_of_line"/>
+<setting id="org.eclipse.jdt.core.formatter.insert_new_line_after_annotation_on_field" value="do not insert"/>
 <setting id="org.eclipse.jdt.core.formatter.comment.indent_root_tags" value="true"/>
+<setting id="org.eclipse.jdt.core.formatter.brace_position_for_enum_constant" value="end_of_line"/>
 <setting id="org.eclipse.jdt.core.formatter.insert_space_before_comma_in_enum_declarations" value="do not insert"/>
 <setting id="org.eclipse.jdt.core.formatter.alignment_for_union_type_in_multicatch" value="16"/>
 <setting id="org.eclipse.jdt.core.formatter.insert_space_after_comma_in_explicitconstructorcall_arguments" value="insert"/>
@@ -150,12 +150,12 @@
 <setting id="org.eclipse.jdt.core.formatter.insert_new_line_after_opening_brace_in_array_initializer" value="do not insert"/>
 <setting id="org.eclipse.jdt.core.formatter.insert_space_after_closing_brace_in_block" value="insert"/>
 <setting id="org.eclipse.jdt.core.formatter.insert_space_before_opening_bracket_in_array_reference" value="do not insert"/>
-<setting id="org.eclipse.jdt.core.formatter.insert_new_line_in_empty_enum_constant" value="insert"/>
+<setting id="org.eclipse.jdt.core.formatter.insert_new_line_in_empty_enum_constant" value="do not insert"/>
 <setting id="org.eclipse.jdt.core.formatter.insert_space_after_opening_angle_bracket_in_type_arguments" value="do not insert"/>
 <setting id="org.eclipse.jdt.core.formatter.insert_space_before_opening_paren_in_constructor_declaration" value="do not insert"/>
 <setting id="org.eclipse.jdt.core.formatter.insert_space_before_comma_in_constructor_declaration_throws" value="do not insert"/>
 <setting id="org.eclipse.jdt.core.formatter.insert_space_after_opening_paren_in_if" value="do not insert"/>
-<setting id="org.eclipse.jdt.core.formatter.comment.clear_blank_lines_in_javadoc_comment" value="false"/>
+<setting id="org.eclipse.jdt.core.formatter.comment.clear_blank_lines_in_javadoc_comment" value="true"/>
 <setting id="org.eclipse.jdt.core.formatter.alignment_for_throws_clause_in_constructor_declaration" value="16"/>
 <setting id="org.eclipse.jdt.core.formatter.insert_space_after_assignment_operator" value="insert"/>
 <setting id="org.eclipse.jdt.core.formatter.insert_space_before_assignment_operator" value="insert"/>
@@ -182,11 +182,11 @@
 <setting id="org.eclipse.jdt.core.formatter.insert_space_before_closing_angle_bracket_in_parameterized_type_reference" value="do not insert"/>
 <setting id="org.eclipse.jdt.core.formatter.insert_space_before_opening_brace_in_anonymous_type_declaration" value="insert"/>
 <setting id="org.eclipse.jdt.core.formatter.keep_empty_array_initializer_on_one_line" value="false"/>
-<setting id="org.eclipse.jdt.core.formatter.insert_new_line_in_empty_enum_declaration" value="insert"/>
+<setting id="org.eclipse.jdt.core.formatter.insert_new_line_in_empty_enum_declaration" value="do not insert"/>
 <setting id="org.eclipse.jdt.core.formatter.keep_imple_if_on_one_line" value="false"/>
 <setting id="org.eclipse.jdt.core.formatter.insert_space_before_comma_in_constructor_declaration_parameters" value="do not insert"/>
 <setting id="org.eclipse.jdt.core.formatter.insert_space_after_closing_angle_bracket_in_type_parameters" value="insert"/>
-<setting id="org.eclipse.jdt.core.formatter.insert_new_line_at_end_of_file_if_missing" value="do not insert"/>
+<setting id="org.eclipse.jdt.core.formatter.insert_new_line_at_end_of_file_if_missing" value="insert"/>
 <setting id="org.eclipse.jdt.core.formatter.insert_space_after_colon_in_for" value="insert"/>
 <setting id="org.eclipse.jdt.core.formatter.insert_space_before_colon_in_labeled_statement" value="do not insert"/>
 <setting id="org.eclipse.jdt.core.formatter.insert_space_before_comma_in_parameterized_type_reference" value="do not insert"/>
@@ -237,7 +237,7 @@
 <setting id="org.eclipse.jdt.core.formatter.alignment_for_throws_clause_in_method_declaration" value="16"/>
 <setting id="org.eclipse.jdt.core.formatter.insert_space_before_closing_angle_bracket_in_type_parameters" value="do not insert"/>
 <setting id="org.eclipse.jdt.core.formatter.insert_space_before_opening_bracket_in_array_allocation_expression" value="do not insert"/>
-<setting id="org.eclipse.jdt.core.formatter.insert_new_line_in_empty_anonymous_type_declaration" value="insert"/>
+<setting id="org.eclipse.jdt.core.formatter.insert_new_line_in_empty_anonymous_type_declaration" value="do not insert"/>
 <setting id="org.eclipse.jdt.core.formatter.insert_space_after_colon_in_conditional" value="insert"/>
 <setting id="org.eclipse.jdt.core.formatter.insert_space_after_opening_angle_bracket_in_parameterized_type_reference" value="do not insert"/>
 <setting id="org.eclipse.jdt.core.formatter.insert_space_before_closing_paren_in_for" value="do not insert"/>
@@ -251,12 +251,12 @@
 <setting id="org.eclipse.jdt.core.compiler.codegen.targetPlatform" value="1.7"/>
 <setting id="org.eclipse.jdt.core.formatter.alignment_for_resources_in_try" value="80"/>
 <setting id="org.eclipse.jdt.core.formatter.use_tabs_only_for_leading_indentations" value="false"/>
-<setting id="org.eclipse.jdt.core.formatter.alignment_for_arguments_in_annotation" value="0"/>
+<setting id="org.eclipse.jdt.core.formatter.alignment_for_arguments_in_annotation" value="16"/>
 <setting id="org.eclipse.jdt.core.formatter.comment.format_header" value="false"/>
 <setting id="org.eclipse.jdt.core.formatter.comment.format_block_comments" value="false"/>
 <setting id="org.eclipse.jdt.core.formatter.insert_space_before_closing_paren_in_enum_constant" value="do not insert"/>
 <setting id="org.eclipse.jdt.core.formatter.alignment_for_enum_constants" value="0"/>
-<setting id="org.eclipse.jdt.core.formatter.insert_new_line_in_empty_block" value="insert"/>
+<setting id="org.eclipse.jdt.core.formatter.insert_new_line_in_empty_block" value="do not insert"/>
 <setting id="org.eclipse.jdt.core.formatter.indent_body_declarations_compare_to_annotation_declaration_header" value="true"/>
 <setting id="org.eclipse.jdt.core.formatter.insert_space_before_closing_paren_in_parenthesized_expression" value="do not insert"/>
 <setting id="org.eclipse.jdt.core.formatter.insert_space_before_opening_paren_in_parenthesized_expression" value="do not insert"/>

pom.xml

@@ -5,7 +5,7 @@
 	
 	<groupId>org.springframework.data</groupId>
 	<artifactId>spring-data-mongodb-parent</artifactId>
-	<version>1.3.0.M1</version>
+	<version>1.4.0.M1</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>1.1.0.RELEASE</version>
+		<version>1.3.0.M1</version>
 		<relativePath>../spring-data-build/parent/pom.xml</relativePath>
 	</parent>
 	
@@ -29,19 +29,19 @@
 	<properties>
 		<project.type>multi</project.type>
 		<dist.id>spring-data-mongodb</dist.id>
-		<springdata.commons>1.6.0.M1</springdata.commons>
-		<mongo>2.10.1</mongo>
+		<springdata.commons>1.7.0.M1</springdata.commons>
+		<mongo>2.11.3</mongo>
 	</properties>
 	
 	<developers>
 		<developer>
 			<id>ogierke</id>
 			<name>Oliver Gierke</name>
-			<email>ogierke at vmware.com</email>
-			<organization>SpringSource</organization>
-			<organizationUrl>http://www.springsource.com</organizationUrl>
+			<email>ogierke at gopivotal.com</email>
+			<organization>Pivotal</organization>
+			<organizationUrl>http://www.gopivotal.com</organizationUrl>
 			<roles>
-				<role>Project Lean</role>
+				<role>Project Lead</role>
 			</roles>
 			<timezone>+1</timezone>
 		</developer>
@@ -49,8 +49,8 @@
 			<id>trisberg</id>
 			<name>Thomas Risberg</name>
 			<email>trisberg at vmware.com</email>
-			<organization>SpringSource</organization>
-			<organizationUrl>http://www.springsource.com</organizationUrl>
+			<organization>Pivotal</organization>
+			<organizationUrl>http://www.gopivotal.com</organizationUrl>
 			<roles>
 				<role>Developer</role>
 			</roles>
@@ -59,9 +59,9 @@
 		<developer>
 			<id>mpollack</id>
 			<name>Mark Pollack</name>
-			<email>mpollack at vmware.com</email>
-			<organization>SpringSource</organization>
-			<organizationUrl>http://www.springsource.com</organizationUrl>
+			<email>mpollack at gopivotal.com</email>
+			<organization>Pivotal</organization>
+			<organizationUrl>http://www.gopivotal.com</organizationUrl>
 			<roles>
 				<role>Developer</role>
 			</roles>
@@ -70,14 +70,25 @@
 		<developer>
 			<id>jbrisbin</id>
 			<name>Jon Brisbin</name>
-			<email>jbrisbin at vmware.com</email>
-			<organization>SpringSource</organization>
-			<organizationUrl>http://www.springsource.com</organizationUrl>
+			<email>jbrisbin at gopivotal.com</email>
+			<organization>Pivotal</organization>
+			<organizationUrl>http://www.gopivotal.com</organizationUrl>
 			<roles>
 				<role>Developer</role>
 			</roles>
 			<timezone>-6</timezone>
 		</developer>
+		<developer>
+			<id>tdarimont</id>
+			<name>Thomas Darimont</name>
+			<email>tdarimont at gopivotal.com</email>
+			<organization>Pivotal</organization>
+			<organizationUrl>http://www.gopivotal.com</organizationUrl>
+			<roles>
+				<role>Developer</role>
+			</roles>
+			<timezone>+1</timezone>
+		</developer>
 	</developers>
 
 	<dependencies>
@@ -91,7 +102,7 @@
 	
 	<repositories>
 		<repository>
-			<id>spring-lib-milestone</id>
+			<id>spring-libs-milestone</id>
 			<url>http://repo.springsource.org/libs-milestone-local</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>1.3.0.M1</version>
+		<version>1.4.0.M1</version>
 		<relativePath>../pom.xml</relativePath>
 	</parent>
 	
@@ -52,7 +52,7 @@
 		<dependency>
 			<groupId>org.springframework.data</groupId>
 			<artifactId>spring-data-mongodb</artifactId>
-			<version>1.3.0.M1</version>
+			<version>1.4.0.M1</version>
 		</dependency>
 
 		<dependency>

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

@@ -0,0 +1,5 @@
+/**
+ * Infrastructure for Spring Data's MongoDB cross store support.
+ */
+package org.springframework.data.mongodb.crossstore;
+

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

@@ -12,7 +12,7 @@ Import-Template:
  org.aspectj.*;version="${aspectj:[1.0.0, 2.0.0)}",
  org.bson.*;version="0",
  org.slf4j.*;version="${slf4j:[=.=.=,+1.0.0)}",
- org.springframework.*;version="${spring30:[=.=.=.=,+1.0.0)}",
+ org.springframework.*;version="${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>1.3.0.M1</version>
+		<version>1.4.0.M1</version>
 		<relativePath>../pom.xml</relativePath>
 	</parent>
 	

spring-data-mongodb-log4j/README.md

@@ -32,7 +32,7 @@ An example log entry might look like:
     {
       "_id" : ObjectId("4d89341a8ef397e06940d5cd"),
       "applicationId" : "my.application",
-      "name" : "org.springframework.data.mongodb.log4j.AppenderTest",
+      "name" : "org.springframework.data.mongodb.log4j.MongoLog4jAppenderIntegrationTests",
       "level" : "DEBUG",
       "timestamp" : ISODate("2011-03-23T16:53:46.778Z"),
       "properties" : {

spring-data-mongodb-log4j/pom.xml

@@ -5,7 +5,7 @@
 	<parent>
 		<groupId>org.springframework.data</groupId>
 		<artifactId>spring-data-mongodb-parent</artifactId>
-		<version>1.3.0.M1</version>
+		<version>1.4.0.M1</version>
 		<relativePath>../pom.xml</relativePath>
 	</parent>
 

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

@@ -0,0 +1,5 @@
+/**
+ * Infrastructure for to use MongoDB as a logging sink.
+ */
+package org.springframework.data.mongodb.log4j;
+

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

@@ -1,11 +1,11 @@
 /*
- * Copyright (c) 2011 by the original author(s).
+ * Copyright 2011-2013 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.
  * You may obtain a copy of the License at
  *
- *     http://www.apache.org/licenses/LICENSE-2.0
+ *      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,
@@ -13,63 +13,65 @@
  * 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.net.UnknownHostException;
 import java.util.Calendar;
 
-import com.mongodb.DB;
-import com.mongodb.DBCursor;
-import com.mongodb.Mongo;
 import org.apache.log4j.Logger;
 import org.apache.log4j.MDC;
 import org.junit.Before;
 import org.junit.Test;
 
-/**
- * @author Jon Brisbin <jbrisbin@vmware.com>
- */
-public class AppenderTest {
+import com.mongodb.DB;
+import com.mongodb.DBCursor;
+import com.mongodb.Mongo;
 
-	private static final String NAME = AppenderTest.class.getName();
-	private Logger log = Logger.getLogger(NAME);
-	private Mongo mongo;
-	private DB db;
-	private String collection;
+/**
+ * Integration tests for {@link MongoLog4jAppender}.
+ * 
+ * @author Jon Brisbin
+ * @author Oliver Gierke
+ */
+public class MongoLog4jAppenderIntegrationTests {
+
+	static final String NAME = MongoLog4jAppenderIntegrationTests.class.getName();
+
+	Logger log = Logger.getLogger(NAME);
+	Mongo mongo;
+	DB db;
+	String collection;
 
 	@Before
-	public void setup() {
-		try {
-			mongo = new Mongo("localhost", 27017);
-			db = mongo.getDB("logs");
-			Calendar now = Calendar.getInstance();
-			collection = String.valueOf(now.get(Calendar.YEAR)) + String.format("%1$02d", now.get(Calendar.MONTH) + 1);
-			db.getCollection(collection).drop();
-		} catch (UnknownHostException e) {
-			throw new RuntimeException(e.getMessage(), e);
-		}
+	public void setUp() throws Exception {
+
+		mongo = new Mongo("localhost", 27017);
+		db = mongo.getDB("logs");
+
+		Calendar now = Calendar.getInstance();
+		collection = String.valueOf(now.get(Calendar.YEAR)) + String.format("%1$02d", now.get(Calendar.MONTH) + 1);
+		db.getCollection(collection).drop();
 	}
 
 	@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));
 
+		assertThat(msgs.count(), is(4));
 	}
 
 	@Test
 	public void testProperties() {
+
 		MDC.put("property", "one");
 		log.debug("DEBUG message");
 	}
-
 }

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

@@ -10,11 +10,4 @@ log4j.appender.stdout.collectionPattern = %X{year}%X{month}
 log4j.appender.stdout.applicationId = my.application
 log4j.appender.stdout.warnOrHigherWriteConcern = FSYNC_SAFE
 
-log4j.category.org.apache.activemq=ERROR
-log4j.category.org.springframework.batch=DEBUG
-log4j.category.org.springframework.data.document.mongodb=DEBUG
-log4j.category.org.springframework.transaction=INFO
-
-log4j.category.org.hibernate.SQL=DEBUG
-# for debugging datasource initialization
-# log4j.category.test.jdbc=DEBUG
+log4j.category.org.springframework.data.mongodb=DEBUG

spring-data-mongodb/Spring Data MongoDB.sonargraph

@@ -1,153 +1,176 @@
 <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
-<context version="7.1.7.187">
-    <scope name="spring-data-mongodb" type="Project">
-        <element name="Filter" type="TypeFilterReferenceOverridden">
-            <element name="org.springframework.data.mongodb.**" type="IncludeTypePattern"/>
+<context version="7.1.9.205">
+    <scope type="Project" name="spring-data-mongodb">
+        <element type="TypeFilterReferenceOverridden" name="Filter">
+            <element type="IncludeTypePattern" name="org.springframework.data.mongodb.**"/>
         </element>
         <architecture>
-            <element name="Config" type="Layer">
-                <element name="Assignment" type="TypeFilter">
-                    <element name="**.config.**" type="WeakTypePattern"/>
+            <element type="Layer" name="Config">
+                <element type="TypeFilter" name="Assignment">
+                    <element type="WeakTypePattern" name="**.config.**"/>
                 </element>
-                <dependency type="AllowedDependency" toName="Project|spring-data-mongodb::Layer|Core"/>
-                <dependency type="AllowedDependency" toName="Project|spring-data-mongodb::Layer|GridFS"/>
-                <dependency type="AllowedDependency" toName="Project|spring-data-mongodb::Layer|Monitoring"/>
-                <dependency type="AllowedDependency" toName="Project|spring-data-mongodb::Layer|Repositories"/>
+                <dependency toName="Project|spring-data-mongodb::Layer|Core" type="AllowedDependency"/>
+                <dependency toName="Project|spring-data-mongodb::Layer|GridFS" type="AllowedDependency"/>
+                <dependency toName="Project|spring-data-mongodb::Layer|Monitoring" type="AllowedDependency"/>
+                <dependency toName="Project|spring-data-mongodb::Layer|Repositories" type="AllowedDependency"/>
             </element>
-            <element name="Repositories" type="Layer">
-                <element name="Assignment" type="TypeFilter">
-                    <element name="**.repository.**" type="IncludeTypePattern"/>
+            <element type="Layer" name="Repositories">
+                <element type="TypeFilter" name="Assignment">
+                    <element type="IncludeTypePattern" name="**.repository.**"/>
                 </element>
-                <element name="API" type="Subsystem">
-                    <element name="Assignment" type="TypeFilter">
-                        <element name="**.repository.*" type="IncludeTypePattern"/>
+                <element type="Subsystem" name="API">
+                    <element type="TypeFilter" name="Assignment">
+                        <element type="IncludeTypePattern" name="**.repository.*"/>
                     </element>
                 </element>
-                <element name="Query" type="Subsystem">
-                    <element name="Assignment" type="TypeFilter">
-                        <element name="**.query.**" type="IncludeTypePattern"/>
+                <element type="Subsystem" name="Query">
+                    <element type="TypeFilter" name="Assignment">
+                        <element type="IncludeTypePattern" name="**.query.**"/>
                     </element>
-                    <dependency type="AllowedDependency" toName="Project|spring-data-mongodb::Layer|Repositories::Subsystem|API"/>
+                    <dependency toName="Project|spring-data-mongodb::Layer|Repositories::Subsystem|API" type="AllowedDependency"/>
                 </element>
-                <element name="Implementation" type="Subsystem">
-                    <element name="Assignment" type="TypeFilter">
-                        <element name="**.support.**" type="IncludeTypePattern"/>
+                <element type="Subsystem" name="Implementation">
+                    <element type="TypeFilter" name="Assignment">
+                        <element type="IncludeTypePattern" name="**.support.**"/>
                     </element>
-                    <dependency type="AllowedDependency" toName="Project|spring-data-mongodb::Layer|Repositories::Subsystem|API"/>
-                    <dependency type="AllowedDependency" toName="Project|spring-data-mongodb::Layer|Repositories::Subsystem|Query"/>
+                    <dependency toName="Project|spring-data-mongodb::Layer|Repositories::Subsystem|API" type="AllowedDependency"/>
+                    <dependency toName="Project|spring-data-mongodb::Layer|Repositories::Subsystem|Query" type="AllowedDependency"/>
                 </element>
-                <element name="Config" type="Subsystem">
-                    <element name="Assignment" type="TypeFilter">
-                        <element name="**.config.**" type="IncludeTypePattern"/>
+                <element type="Subsystem" name="Config">
+                    <element type="TypeFilter" name="Assignment">
+                        <element type="IncludeTypePattern" name="**.config.**"/>
                     </element>
-                    <dependency type="AllowedDependency" toName="Project|spring-data-mongodb::Layer|Repositories::Subsystem|Implementation"/>
+                    <dependency toName="Project|spring-data-mongodb::Layer|Repositories::Subsystem|Implementation" type="AllowedDependency"/>
                 </element>
-                <dependency type="AllowedDependency" toName="Project|spring-data-mongodb::Layer|Core"/>
+                <dependency toName="Project|spring-data-mongodb::Layer|Core" type="AllowedDependency"/>
             </element>
-            <element name="Monitoring" type="Layer">
-                <element name="Assignment" type="TypeFilter">
-                    <element name="**.monitor.**" type="IncludeTypePattern"/>
+            <element type="Layer" name="Monitoring">
+                <element type="TypeFilter" name="Assignment">
+                    <element type="IncludeTypePattern" name="**.monitor.**"/>
                 </element>
-                <dependency type="AllowedDependency" toName="Project|spring-data-mongodb::Layer|Core"/>
+                <dependency toName="Project|spring-data-mongodb::Layer|Core" type="AllowedDependency"/>
             </element>
-            <element name="GridFS" type="Layer">
-                <element name="Assignment" type="TypeFilter">
-                    <element name="**.gridfs.**" type="IncludeTypePattern"/>
+            <element type="Layer" name="GridFS">
+                <element type="TypeFilter" name="Assignment">
+                    <element type="IncludeTypePattern" name="**.gridfs.**"/>
                 </element>
-                <dependency type="AllowedDependency" toName="Project|spring-data-mongodb::Layer|Core"/>
+                <dependency toName="Project|spring-data-mongodb::Layer|Core" type="AllowedDependency"/>
             </element>
-            <element name="Core" type="Layer">
-                <element name="Assignment" type="TypeFilter">
-                    <element name="**.core.**" type="IncludeTypePattern"/>
+            <element type="Layer" name="Core">
+                <element type="TypeFilter" name="Assignment">
+                    <element type="IncludeTypePattern" name="**.core.**"/>
                 </element>
-                <element name="Mapping" type="Subsystem">
-                    <element name="Assignment" type="TypeFilter">
-                        <element name="**.mapping.**" type="IncludeTypePattern"/>
+                <element type="Subsystem" name="Mapping">
+                    <element type="TypeFilter" name="Assignment">
+                        <element type="IncludeTypePattern" name="**.mapping.**"/>
                     </element>
                 </element>
-                <element name="Geospatial" type="Subsystem">
-                    <element name="Assignment" type="TypeFilter">
-                        <element name="**.geo.**" type="IncludeTypePattern"/>
+                <element type="Subsystem" name="Geospatial">
+                    <element type="TypeFilter" name="Assignment">
+                        <element type="IncludeTypePattern" name="**.geo.**"/>
                     </element>
-                    <dependency type="AllowedDependency" toName="Project|spring-data-mongodb::Layer|Core::Subsystem|Mapping"/>
+                    <dependency toName="Project|spring-data-mongodb::Layer|Core::Subsystem|Mapping" type="AllowedDependency"/>
                 </element>
-                <element name="Query" type="Subsystem">
-                    <element name="Assignment" type="TypeFilter">
-                        <element name="**.query.**" type="IncludeTypePattern"/>
+                <element type="Subsystem" name="Query">
+                    <element type="TypeFilter" name="Assignment">
+                        <element type="IncludeTypePattern" name="**.query.**"/>
                     </element>
-                    <dependency type="AllowedDependency" toName="Project|spring-data-mongodb::Layer|Core::Subsystem|Geospatial"/>
+                    <dependency toName="Project|spring-data-mongodb::Layer|Core::Subsystem|Geospatial" type="AllowedDependency"/>
                 </element>
-                <element name="Index" type="Subsystem">
-                    <element name="Assignment" type="TypeFilter">
-                        <element name="**.index.**" type="IncludeTypePattern"/>
+                <element type="Subsystem" name="Conversion">
+                    <element type="TypeFilter" name="Assignment">
+                        <element type="IncludeTypePattern" name="**.convert.**"/>
                     </element>
-                    <dependency type="AllowedDependency" toName="Project|spring-data-mongodb::Layer|Core::Subsystem|Mapping"/>
-                    <dependency type="AllowedDependency" toName="Project|spring-data-mongodb::Layer|Core::Subsystem|Query"/>
+                    <dependency toName="Project|spring-data-mongodb::Layer|Core::Subsystem|Mapping" type="AllowedDependency"/>
+                    <dependency toName="Project|spring-data-mongodb::Layer|Core::Subsystem|Query" type="AllowedDependency"/>
                 </element>
-                <element name="Core" type="Subsystem">
-                    <element name="Assignment" type="TypeFilter">
-                        <element name="**.core.**" type="WeakTypePattern"/>
+                <element type="Subsystem" name="SpEL">
+                    <element type="TypeFilter" name="Assignment">
+                        <element type="IncludeTypePattern" name="**.spel.**"/>
                     </element>
-                    <dependency type="AllowedDependency" toName="Project|spring-data-mongodb::Layer|Core::Subsystem|Geospatial"/>
-                    <dependency type="AllowedDependency" toName="Project|spring-data-mongodb::Layer|Core::Subsystem|Index"/>
-                    <dependency type="AllowedDependency" toName="Project|spring-data-mongodb::Layer|Core::Subsystem|Mapping"/>
-                    <dependency type="AllowedDependency" toName="Project|spring-data-mongodb::Layer|Core::Subsystem|Query"/>
+                </element>
+                <element type="Subsystem" name="Aggregation">
+                    <element type="TypeFilter" name="Assignment">
+                        <element type="IncludeTypePattern" name="**.aggregation.**"/>
+                    </element>
+                    <dependency toName="Project|spring-data-mongodb::Layer|Core::Subsystem|Conversion" type="AllowedDependency"/>
+                    <dependency toName="Project|spring-data-mongodb::Layer|Core::Subsystem|Mapping" type="AllowedDependency"/>
+                    <dependency toName="Project|spring-data-mongodb::Layer|Core::Subsystem|Query" type="AllowedDependency"/>
+                    <dependency toName="Project|spring-data-mongodb::Layer|Core::Subsystem|SpEL" type="AllowedDependency"/>
+                </element>
+                <element type="Subsystem" name="Index">
+                    <element type="TypeFilter" name="Assignment">
+                        <element type="IncludeTypePattern" name="**.index.**"/>
+                    </element>
+                    <dependency toName="Project|spring-data-mongodb::Layer|Core::Subsystem|Mapping" type="AllowedDependency"/>
+                    <dependency toName="Project|spring-data-mongodb::Layer|Core::Subsystem|Query" type="AllowedDependency"/>
+                </element>
+                <element type="Subsystem" name="Core">
+                    <element type="TypeFilter" name="Assignment">
+                        <element type="WeakTypePattern" name="**.core.**"/>
+                    </element>
+                    <dependency toName="Project|spring-data-mongodb::Layer|Core::Subsystem|Aggregation" type="AllowedDependency"/>
+                    <dependency toName="Project|spring-data-mongodb::Layer|Core::Subsystem|Conversion" type="AllowedDependency"/>
+                    <dependency toName="Project|spring-data-mongodb::Layer|Core::Subsystem|Geospatial" type="AllowedDependency"/>
+                    <dependency toName="Project|spring-data-mongodb::Layer|Core::Subsystem|Index" type="AllowedDependency"/>
+                    <dependency toName="Project|spring-data-mongodb::Layer|Core::Subsystem|Mapping" type="AllowedDependency"/>
+                    <dependency toName="Project|spring-data-mongodb::Layer|Core::Subsystem|Query" type="AllowedDependency"/>
                 </element>
             </element>
-            <element name="API" type="Subsystem">
-                <element name="Assignment" type="TypeFilter">
-                    <element name="org.springframework.data.mongodb.*" type="IncludeTypePattern"/>
+            <element type="Subsystem" name="API">
+                <element type="TypeFilter" name="Assignment">
+                    <element type="IncludeTypePattern" name="org.springframework.data.mongodb.*"/>
                 </element>
                 <stereotype name="Public"/>
             </element>
         </architecture>
         <workspace>
-            <element name="src/main/java" type="JavaRootDirectory">
+            <element type="JavaRootDirectory" name="src/main/java">
                 <reference name="Project|spring-data-mongodb::BuildUnit|spring-data-mongodb"/>
             </element>
-            <element name="target/classes" type="JavaRootDirectory">
+            <element type="JavaRootDirectory" name="target/classes">
                 <reference name="Project|spring-data-mongodb::BuildUnit|spring-data-mongodb"/>
             </element>
         </workspace>
         <physical>
-            <element name="spring-data-mongodb" type="BuildUnit"/>
+            <element type="BuildUnit" name="spring-data-mongodb"/>
         </physical>
     </scope>
-    <scope name="External" type="External">
-        <element name="Filter" type="TypeFilter">
-            <element name="**" type="IncludeTypePattern"/>
-            <element name="java.**" type="ExcludeTypePattern"/>
-            <element name="javax.**" type="ExcludeTypePattern"/>
+    <scope type="External" name="External">
+        <element type="TypeFilter" name="Filter">
+            <element type="IncludeTypePattern" name="**"/>
+            <element type="ExcludeTypePattern" name="java.**"/>
+            <element type="ExcludeTypePattern" name="javax.**"/>
         </element>
         <architecture>
-            <element name="Spring" type="Subsystem">
-                <element name="Assignment" type="TypeFilter">
-                    <element name="org.springframework.**" type="IncludeTypePattern"/>
-                    <element name="org.springframework.data.**" type="ExcludeTypePattern"/>
+            <element type="Subsystem" name="Spring">
+                <element type="TypeFilter" name="Assignment">
+                    <element type="IncludeTypePattern" name="org.springframework.**"/>
+                    <element type="ExcludeTypePattern" name="org.springframework.data.**"/>
                 </element>
             </element>
-            <element name="Spring Data Core" type="Subsystem">
-                <element name="Assignment" type="TypeFilter">
-                    <element name="org.springframework.data.**" type="IncludeTypePattern"/>
+            <element type="Subsystem" name="Spring Data Core">
+                <element type="TypeFilter" name="Assignment">
+                    <element type="IncludeTypePattern" name="org.springframework.data.**"/>
                 </element>
             </element>
-            <element name="Mongo Java Driver" type="Subsystem">
-                <element name="Assignment" type="TypeFilter">
-                    <element name="com.mongodb.**" type="IncludeTypePattern"/>
-                    <element name="org.bson.**" type="IncludeTypePattern"/>
+            <element type="Subsystem" name="Mongo Java Driver">
+                <element type="TypeFilter" name="Assignment">
+                    <element type="IncludeTypePattern" name="com.mongodb.**"/>
+                    <element type="IncludeTypePattern" name="org.bson.**"/>
                 </element>
             </element>
-            <element name="Querydsl" type="Subsystem">
-                <element name="Assignment" type="TypeFilter">
-                    <element name="com.mysema.query.**" type="IncludeTypePattern"/>
+            <element type="Subsystem" name="Querydsl">
+                <element type="TypeFilter" name="Assignment">
+                    <element type="IncludeTypePattern" name="com.mysema.query.**"/>
                 </element>
             </element>
         </architecture>
     </scope>
-    <scope name="Global" type="Global">
-        <element name="Configuration" type="Configuration"/>
-        <element name="Filter" type="TypeFilter">
-            <element name="**" type="IncludeTypePattern"/>
+    <scope type="Global" name="Global">
+        <element type="Configuration" name="Configuration"/>
+        <element type="TypeFilter" name="Filter">
+            <element type="IncludeTypePattern" name="**"/>
         </element>
     </scope>
 </context>

spring-data-mongodb/pom.xml

@@ -11,12 +11,13 @@
 	<parent>
 		<groupId>org.springframework.data</groupId>
 		<artifactId>spring-data-mongodb-parent</artifactId>
-		<version>1.3.0.M1</version>
+		<version>1.4.0.M1</version>
 		<relativePath>../pom.xml</relativePath>
 	</parent>
 
 	<properties>
 		<validation>1.0.0.GA</validation>
+		<objenesis>1.3</objenesis>
 	</properties>
 
 	<dependencies>
@@ -55,7 +56,7 @@
 		</dependency>
 
 		<!--  Spring Data -->
-			<dependency>
+		<dependency>
 			<groupId>${project.groupId}</groupId>
 			<artifactId>spring-data-commons</artifactId>
 			<version>${springdata.commons}</version>
@@ -119,6 +120,13 @@
 			<version>${validation}</version>
 			<optional>true</optional>
 		</dependency>
+		
+		<dependency>
+			<groupId>org.objenesis</groupId>
+			<artifactId>objenesis</artifactId>
+			<version>${objenesis}</version>
+			<optional>true</optional>
+		</dependency>
 
 		<dependency>
 			<groupId>org.hibernate</groupId>

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

@@ -0,0 +1,34 @@
+/*
+ * 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.
+ * 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.UncategorizedDataAccessException;
+
+/**
+ * @author Oliver Gierke
+ */
+public class LazyLoadingException extends UncategorizedDataAccessException {
+
+	private static final long serialVersionUID = -7089224903873220037L;
+
+	/**
+	 * @param msg
+	 * @param cause
+	 */
+	public LazyLoadingException(String msg, Throwable cause) {
+		super(msg, cause);
+	}
+}

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

@@ -1,6 +1,23 @@
+/*
+ * Copyright 2011-2013 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.
+ * 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.DB;
 
@@ -8,6 +25,7 @@ import com.mongodb.DB;
  * Interface for factories creating {@link DB} instances.
  * 
  * @author Mark Pollack
+ * @author Thomas Darimont
  */
 public interface MongoDbFactory {
 
@@ -27,4 +45,11 @@ public interface MongoDbFactory {
 	 * @throws DataAccessException
 	 */
 	DB getDb(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

@@ -31,6 +31,8 @@ import org.springframework.data.mapping.context.MappingContextIsNewStrategyFacto
 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.CamelCaseAbbreviatingFieldNamingStrategy;
 import org.springframework.data.mongodb.core.mapping.Document;
@@ -47,6 +49,7 @@ import com.mongodb.Mongo;
  * 
  * @author Mark Pollack
  * @author Oliver Gierke
+ * @author Thomas Darimont
  */
 @Configuration
 public abstract class AbstractMongoConfiguration {
@@ -58,6 +61,16 @@ public abstract class AbstractMongoConfiguration {
 	 */
 	protected abstract String getDatabaseName();
 
+	/**
+	 * Return the name of the authentication database to use. Defaults to {@literal null} and will turn into the value
+	 * returned by {@link #getDatabaseName()} later on effectively.
+	 * 
+	 * @return
+	 */
+	protected String getAuthenticationDatabaseName() {
+		return null;
+	}
+
 	/**
 	 * Return the {@link Mongo} instance to connect to. Annotate with {@link Bean} in case you want to expose a
 	 * {@link Mongo} instance to the {@link org.springframework.context.ApplicationContext}.
@@ -89,14 +102,7 @@ public abstract class AbstractMongoConfiguration {
 	 */
 	@Bean
 	public SimpleMongoDbFactory mongoDbFactory() throws Exception {
-
-		UserCredentials credentials = getUserCredentials();
-
-		if (credentials == null) {
-			return new SimpleMongoDbFactory(mongo(), getDatabaseName());
-		} else {
-			return new SimpleMongoDbFactory(mongo(), getDatabaseName(), credentials);
-		}
+		return new SimpleMongoDbFactory(mongo(), getDatabaseName(), getUserCredentials(), getAuthenticationDatabaseName());
 	}
 
 	/**
@@ -178,8 +184,11 @@ public abstract class AbstractMongoConfiguration {
 	 */
 	@Bean
 	public MappingMongoConverter mappingMongoConverter() throws Exception {
-		MappingMongoConverter converter = new MappingMongoConverter(mongoDbFactory(), mongoMappingContext());
+
+		DbRefResolver dbRefResolver = new DefaultDbRefResolver(mongoDbFactory());
+		MappingMongoConverter converter = new MappingMongoConverter(dbRefResolver, mongoMappingContext());
 		converter.setCustomConversions(customConversions());
+
 		return converter;
 	}
 

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

@@ -0,0 +1,70 @@
+/*
+ * 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.
+ * 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.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Inherited;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+import org.springframework.context.annotation.Import;
+import org.springframework.data.auditing.DateTimeProvider;
+import org.springframework.data.domain.AuditorAware;
+
+/**
+ * Annotation to enable auditing in MongoDB via annotation configuration.
+ * 
+ * @author Thomas Darimont
+ * @author Oliver Gierke
+ */
+@Inherited
+@Documented
+@Target(ElementType.TYPE)
+@Retention(RetentionPolicy.RUNTIME)
+@Import(MongoAuditingRegistrar.class)
+public @interface EnableMongoAuditing {
+
+	/**
+	 * Configures the {@link AuditorAware} bean to be used to lookup the current principal.
+	 * 
+	 * @return
+	 */
+	String auditorAwareRef() default "";
+
+	/**
+	 * Configures whether the creation and modification dates are set. Defaults to {@literal true}.
+	 * 
+	 * @return
+	 */
+	boolean setDates() default true;
+
+	/**
+	 * Configures whether the entity shall be marked as modified on creation. Defaults to {@literal true}.
+	 * 
+	 * @return
+	 */
+	boolean modifyOnCreate() default true;
+
+	/**
+	 * Configures a {@link DateTimeProvider} bean name that allows customizing the {@link org.joda.time.DateTime} to be
+	 * used for setting creation and modification dates.
+	 * 
+	 * @return
+	 */
+	String dateTimeProviderRef() default "";
+}

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

@@ -70,6 +70,7 @@ import org.w3c.dom.Element;
  * @author Jon Brisbin
  * @author Oliver Gierke
  * @author Maciej Walkowiak
+ * @author Thomas Darimont
  */
 public class MappingMongoConverterParser implements BeanDefinitionParser {
 
@@ -105,6 +106,11 @@ public class MappingMongoConverterParser implements BeanDefinitionParser {
 		converterBuilder.addConstructorArgReference(dbFactoryRef);
 		converterBuilder.addConstructorArgReference(ctxRef);
 
+		String typeMapperRef = element.getAttribute("type-mapper-ref");
+		if (StringUtils.hasText(typeMapperRef)) {
+			converterBuilder.addPropertyReference("typeMapper", typeMapperRef);
+		}
+
 		if (conversionsDefinition != null) {
 			converterBuilder.addPropertyValue("customConversions", conversionsDefinition);
 		}

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

@@ -0,0 +1,105 @@
+/*
+ * 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.
+ * 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.lang.annotation.Annotation;
+
+import org.springframework.beans.factory.config.BeanDefinition;
+import org.springframework.beans.factory.support.BeanDefinitionBuilder;
+import org.springframework.beans.factory.support.BeanDefinitionRegistry;
+import org.springframework.context.annotation.ImportBeanDefinitionRegistrar;
+import org.springframework.core.type.AnnotationMetadata;
+import org.springframework.data.auditing.IsNewAwareAuditingHandler;
+import org.springframework.data.auditing.config.AnnotationAuditingConfiguration;
+import org.springframework.data.auditing.config.AuditingBeanDefinitionRegistrarSupport;
+import org.springframework.data.mapping.context.MappingContextIsNewStrategyFactory;
+import org.springframework.data.mongodb.core.mapping.event.AuditingEventListener;
+import org.springframework.data.support.IsNewStrategyFactory;
+import org.springframework.util.Assert;
+
+/**
+ * {@link ImportBeanDefinitionRegistrar} to enable {@link EnableMongoAuditing} annotation.
+ * 
+ * @author Thomas Darimont
+ * @author Oliver Gierke
+ */
+class MongoAuditingRegistrar extends AuditingBeanDefinitionRegistrarSupport {
+
+	/* 
+	 * (non-Javadoc)
+	 * @see org.springframework.data.auditing.config.AuditingBeanDefinitionRegistrarSupport#getAnnotation()
+	 */
+	@Override
+	protected Class<? extends Annotation> getAnnotation() {
+		return EnableMongoAuditing.class;
+	}
+
+	/* 
+	 * (non-Javadoc)
+	 * @see org.springframework.data.auditing.config.AuditingBeanDefinitionRegistrarSupport#registerBeanDefinitions(org.springframework.core.type.AnnotationMetadata, org.springframework.beans.factory.support.BeanDefinitionRegistry)
+	 */
+	@Override
+	public void registerBeanDefinitions(AnnotationMetadata annotationMetadata, BeanDefinitionRegistry registry) {
+
+		Assert.notNull(annotationMetadata, "AnnotationMetadata must not be null!");
+		Assert.notNull(registry, "BeanDefinitionRegistry must not be null!");
+
+		registerIsNewStrategyFactoryIfNecessary(registry);
+		super.registerBeanDefinitions(annotationMetadata, registry);
+	}
+
+	/* 
+	 * (non-Javadoc)
+	 * @see org.springframework.data.auditing.config.AuditingBeanDefinitionRegistrarSupport#getAuditHandlerBeanDefinitionBuilder(org.springframework.data.auditing.config.AnnotationAuditingConfiguration)
+	 */
+	@Override
+	protected BeanDefinitionBuilder getAuditHandlerBeanDefinitionBuilder(AnnotationAuditingConfiguration configuration) {
+
+		Assert.notNull(configuration, "AnnotationAuditingConfiguration must not be null!");
+
+		return configureDefaultAuditHandlerAttributes(configuration,
+				BeanDefinitionBuilder.rootBeanDefinition(IsNewAwareAuditingHandler.class)).addConstructorArgReference(
+				BeanNames.IS_NEW_STRATEGY_FACTORY);
+	}
+
+	/* 
+	 * (non-Javadoc)
+	 * @see org.springframework.data.auditing.config.AuditingBeanDefinitionRegistrarSupport#registerAuditListener(org.springframework.beans.factory.config.BeanDefinition, org.springframework.beans.factory.support.BeanDefinitionRegistry)
+	 */
+	@Override
+	protected void registerAuditListenerBeanDefinition(BeanDefinition auditingHandlerDefinition,
+			BeanDefinitionRegistry registry) {
+
+		Assert.notNull(auditingHandlerDefinition, "BeanDefinition must not be null!");
+		Assert.notNull(registry, "BeanDefinitionRegistry must not be null!");
+
+		registerInfrastructureBeanWithId(BeanDefinitionBuilder.rootBeanDefinition(AuditingEventListener.class)
+				.addConstructorArgValue(auditingHandlerDefinition).getRawBeanDefinition(),
+				AuditingEventListener.class.getName(), registry);
+	}
+
+	/**
+	 * @param registry, the {@link BeanDefinitionRegistry} to use to register an {@link IsNewStrategyFactory} to.
+	 */
+	private void registerIsNewStrategyFactoryIfNecessary(BeanDefinitionRegistry registry) {
+
+		if (!registry.containsBeanDefinition(BeanNames.IS_NEW_STRATEGY_FACTORY)) {
+			registry.registerBeanDefinition(BeanNames.IS_NEW_STRATEGY_FACTORY,
+					BeanDefinitionBuilder.rootBeanDefinition(MappingContextIsNewStrategyFactory.class)
+							.addConstructorArgReference(BeanNames.MAPPING_CONTEXT).getBeanDefinition());
+		}
+	}
+}

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2011-2012 by the original author(s).
+ * Copyright 2011-2013 by the original author(s).
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -41,6 +41,7 @@ import com.mongodb.MongoURI;
  * 
  * @author Jon Brisbin
  * @author Oliver Gierke
+ * @author Thomas Darimont
  */
 public class MongoDbFactoryParser extends AbstractBeanDefinitionParser {
 
@@ -70,6 +71,7 @@ public class MongoDbFactoryParser extends AbstractBeanDefinitionParser {
 		String uri = element.getAttribute("uri");
 		String mongoRef = element.getAttribute("mongo-ref");
 		String dbname = element.getAttribute("dbname");
+
 		BeanDefinition userCredentials = getUserCredentialsBeanDefinition(element, parserContext);
 
 		// Common setup
@@ -92,12 +94,9 @@ public class MongoDbFactoryParser extends AbstractBeanDefinitionParser {
 			dbFactoryBuilder.addConstructorArgValue(registerMongoBeanDefinition(element, parserContext));
 		}
 
-		dbname = StringUtils.hasText(dbname) ? dbname : "db";
-		dbFactoryBuilder.addConstructorArgValue(dbname);
-
-		if (userCredentials != null) {
-			dbFactoryBuilder.addConstructorArgValue(userCredentials);
-		}
+		dbFactoryBuilder.addConstructorArgValue(StringUtils.hasText(dbname) ? dbname : "db");
+		dbFactoryBuilder.addConstructorArgValue(userCredentials);
+		dbFactoryBuilder.addConstructorArgValue(element.getAttribute("authentication-dbname"));
 
 		BeanDefinitionBuilder writeConcernPropertyEditorBuilder = getWriteConcernPropertyEditorBuilder();
 

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2011-2012 the original author or authors.
+ * Copyright 2011-2013 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.
@@ -33,6 +33,7 @@ import org.w3c.dom.Element;
  * 
  * @author Mark Pollack
  * @author Oliver Gierke
+ * @author Thomas Darimont
  */
 abstract class MongoParsingUtils {
 
@@ -79,6 +80,8 @@ abstract class MongoParsingUtils {
 		setPropertyValue(optionsDefBuilder, optionsElement, "write-timeout", "writeTimeout");
 		setPropertyValue(optionsDefBuilder, optionsElement, "write-fsync", "writeFsync");
 		setPropertyValue(optionsDefBuilder, optionsElement, "slave-ok", "slaveOk");
+		setPropertyValue(optionsDefBuilder, optionsElement, "ssl", "ssl");
+		setPropertyReference(optionsDefBuilder, optionsElement, "ssl-socket-factory-ref", "sslSocketFactory");
 
 		mongoBuilder.addPropertyValue("mongoOptions", optionsDefBuilder.getBeanDefinition());
 		return true;

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2011 the original author or authors.
+ * Copyright 2011-2013 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.
@@ -31,6 +31,7 @@ import com.mongodb.ServerAddress;
  * 
  * @author Mark Pollack
  * @author Oliver Gierke
+ * @author Thomas Darimont
  */
 public class ServerAddressPropertyEditor extends PropertyEditorSupport {
 
@@ -43,6 +44,11 @@ public class ServerAddressPropertyEditor extends PropertyEditorSupport {
 	@Override
 	public void setAsText(String replicaSetString) {
 
+		if (!StringUtils.hasText(replicaSetString)) {
+			setValue(null);
+			return;
+		}
+
 		String[] replicaSetStringArray = StringUtils.commaDelimitedListToStringArray(replicaSetString);
 		Set<ServerAddress> serverAddresses = new HashSet<ServerAddress>(replicaSetStringArray.length);
 

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2011 the original author or authors.
+ * Copyright 2011-2013 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.
@@ -15,6 +15,8 @@
  */
 package org.springframework.data.mongodb.core;
 
+import static org.springframework.data.domain.Sort.Direction.*;
+
 import java.util.ArrayList;
 import java.util.List;
 
@@ -22,7 +24,6 @@ import org.springframework.dao.DataAccessException;
 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.data.mongodb.core.query.Order;
 import org.springframework.util.Assert;
 
 import com.mongodb.DBCollection;
@@ -34,9 +35,13 @@ import com.mongodb.MongoException;
  * 
  * @author Mark Pollack
  * @author Oliver Gierke
+ * @author Komi Innocent
  */
 public class DefaultIndexOperations implements IndexOperations {
 
+	private static final Double ONE = Double.valueOf(1);
+	private static final Double MINUS_ONE = Double.valueOf(-1);
+
 	private final MongoOperations mongoOperations;
 	private final String collectionName;
 
@@ -135,12 +140,17 @@ public class DefaultIndexOperations implements IndexOperations {
 
 						Object value = keyDbObject.get(key);
 
-						if (Integer.valueOf(1).equals(value)) {
-							indexFields.add(IndexField.create(key, Order.ASCENDING));
-						} else if (Integer.valueOf(-1).equals(value)) {
-							indexFields.add(IndexField.create(key, Order.DESCENDING));
-						} else if ("2d".equals(value)) {
+						if ("2d".equals(value)) {
 							indexFields.add(IndexField.geo(key));
+						} 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));
+							}
 						}
 					}
 

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2011-2012 the original author or authors.
+ * Copyright 2011-2013 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.
@@ -27,6 +27,7 @@ import com.mongodb.Mongo;
  * Mongo server administration exposed via JMX annotations
  * 
  * @author Mark Pollack
+ * @author Thomas Darimont
  */
 @ManagedResource(description = "Mongo Admin Operations")
 public class MongoAdmin implements MongoAdminOperations {
@@ -34,6 +35,7 @@ public class MongoAdmin implements MongoAdminOperations {
 	private final Mongo mongo;
 	private String username;
 	private String password;
+	private String authenticationDatabaseName;
 
 	public MongoAdmin(Mongo mongo) {
 		Assert.notNull(mongo);
@@ -82,7 +84,16 @@ 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;
+	}
+
 	DB getDB(String databaseName) {
-		return MongoDbUtils.getDB(mongo, databaseName, new UserCredentials(username, password));
+		return MongoDbUtils.getDB(mongo, databaseName, new UserCredentials(username, password), authenticationDatabaseName);
 	}
 }

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2011 the original author or authors.
+ * Copyright 2010-2013 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.
@@ -26,14 +26,14 @@ import com.mongodb.DB;
 import com.mongodb.Mongo;
 
 /**
- * Helper class featuring helper methods for internal MongoDb classes.
- * <p/>
- * <p>
- * Mainly intended for internal use within the framework.
+ * Helper class featuring helper methods for internal MongoDb classes. Mainly intended for internal use within the
+ * framework.
  * 
  * @author Thomas Risberg
  * @author Graeme Rocher
  * @author Oliver Gierke
+ * @author Randy Watler
+ * @author Thomas Darimont
  * @since 1.0
  */
 public abstract class MongoDbUtils {
@@ -55,7 +55,7 @@ public abstract class MongoDbUtils {
 	 * @return the {@link DB} connection
 	 */
 	public static DB getDB(Mongo mongo, String databaseName) {
-		return doGetDB(mongo, databaseName, UserCredentials.NO_CREDENTIALS, true);
+		return doGetDB(mongo, databaseName, UserCredentials.NO_CREDENTIALS, true, databaseName);
 	}
 
 	/**
@@ -67,15 +67,22 @@ public abstract class MongoDbUtils {
 	 * @return the {@link DB} connection
 	 */
 	public static DB getDB(Mongo mongo, String databaseName, UserCredentials credentials) {
+		return getDB(mongo, databaseName, credentials, databaseName);
+	}
+
+	public static DB getDB(Mongo mongo, String databaseName, UserCredentials credentials,
+			String authenticationDatabaseName) {
 
 		Assert.notNull(mongo, "No Mongo instance specified!");
 		Assert.hasText(databaseName, "Database name must be given!");
 		Assert.notNull(credentials, "Credentials must not be null, use UserCredentials.NO_CREDENTIALS!");
+		Assert.hasText(authenticationDatabaseName, "Authentication database name must not be null or empty!");
 
-		return doGetDB(mongo, databaseName, credentials, true);
+		return doGetDB(mongo, databaseName, credentials, true, authenticationDatabaseName);
 	}
 
-	private static DB doGetDB(Mongo mongo, String databaseName, UserCredentials credentials, boolean allowCreate) {
+	private static DB doGetDB(Mongo mongo, String databaseName, UserCredentials credentials, boolean allowCreate,
+			String authenticationDatabaseName) {
 
 		DbHolder dbHolder = (DbHolder) TransactionSynchronizationManager.getResource(mongo);
 
@@ -104,14 +111,16 @@ public abstract class MongoDbUtils {
 		DB db = mongo.getDB(databaseName);
 		boolean credentialsGiven = credentials.hasUsername() && credentials.hasPassword();
 
-		synchronized (db) {
+		DB authDb = databaseName.equals(authenticationDatabaseName) ? db : mongo.getDB(authenticationDatabaseName);
 
-			if (credentialsGiven && !db.isAuthenticated()) {
+		synchronized (authDb) {
+
+			if (credentialsGiven && !authDb.isAuthenticated()) {
 
 				String username = credentials.getUsername();
 				String password = credentials.hasPassword() ? credentials.getPassword() : null;
 
-				if (!db.authenticate(username, password == null ? null : password.toCharArray())) {
+				if (!authDb.authenticate(username, password == null ? null : password.toCharArray())) {
 					throw new CannotGetMongoDbConnectionException("Failed to authenticate to database [" + databaseName + "], "
 							+ credentials.toString(), databaseName, credentials);
 				}
@@ -131,8 +140,11 @@ public abstract class MongoDbUtils {
 				holderToUse.addDB(databaseName, db);
 			}
 
-			TransactionSynchronizationManager.registerSynchronization(new MongoSynchronization(holderToUse, mongo));
-			holderToUse.setSynchronizedWithTransaction(true);
+			// synchronize holder only if not yet synchronized
+			if (!holderToUse.isSynchronizedWithTransaction()) {
+				TransactionSynchronizationManager.registerSynchronization(new MongoSynchronization(holderToUse, mongo));
+				holderToUse.setSynchronizedWithTransaction(true);
+			}
 
 			if (holderToUse != dbHolder) {
 				TransactionSynchronizationManager.bindResource(mongo, holderToUse);

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

@@ -15,7 +15,9 @@
  */
 package org.springframework.data.mongodb.core;
 
-import java.util.Arrays;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
 import java.util.List;
 
 import org.springframework.beans.factory.DisposableBean;
@@ -24,6 +26,7 @@ import org.springframework.beans.factory.InitializingBean;
 import org.springframework.dao.DataAccessException;
 import org.springframework.dao.support.PersistenceExceptionTranslator;
 import org.springframework.data.mongodb.CannotGetMongoDbConnectionException;
+import org.springframework.util.StringUtils;
 
 import com.mongodb.Mongo;
 import com.mongodb.MongoOptions;
@@ -36,6 +39,7 @@ import com.mongodb.WriteConcern;
  * @author Thomas Risberg
  * @author Graeme Rocher
  * @author Oliver Gierke
+ * @author Thomas Darimont
  * @since 1.0
  */
 public class MongoFactoryBean implements FactoryBean<Mongo>, InitializingBean, DisposableBean,
@@ -57,11 +61,38 @@ public class MongoFactoryBean implements FactoryBean<Mongo>, InitializingBean, D
 	}
 
 	public void setReplicaSetSeeds(ServerAddress[] replicaSetSeeds) {
-		this.replicaSetSeeds = Arrays.asList(replicaSetSeeds);
+		this.replicaSetSeeds = filterNonNullElementsAsList(replicaSetSeeds);
 	}
 
+	/**
+	 * @deprecated use {@link #setReplicaSetSeeds(ServerAddress[])} instead
+	 * 
+	 * @param replicaPair
+	 */
+	@Deprecated
 	public void setReplicaPair(ServerAddress[] replicaPair) {
-		this.replicaPair = Arrays.asList(replicaPair);
+		this.replicaPair = filterNonNullElementsAsList(replicaPair);
+	}
+
+	/**
+	 * @param elements the elements to filter <T>
+	 * @return a new unmodifiable {@link List#} from the given elements without nulls
+	 */
+	private <T> List<T> filterNonNullElementsAsList(T[] elements) {
+
+		if (elements == null) {
+			return Collections.emptyList();
+		}
+
+		List<T> candidateElements = new ArrayList<T>();
+
+		for (T element : elements) {
+			if (element != null) {
+				candidateElements.add(element);
+			}
+		}
+
+		return Collections.unmodifiableList(candidateElements);
 	}
 
 	public void setHost(String host) {
@@ -127,15 +158,15 @@ public class MongoFactoryBean implements FactoryBean<Mongo>, InitializingBean, D
 			mongoOptions = new MongoOptions();
 		}
 
-		if (replicaPair != null) {
+		if (!isNullOrEmpty(replicaPair)) {
 			if (replicaPair.size() < 2) {
 				throw new CannotGetMongoDbConnectionException("A replica pair must have two server entries");
 			}
 			mongo = new Mongo(replicaPair.get(0), replicaPair.get(1), mongoOptions);
-		} else if (replicaSetSeeds != null) {
+		} else if (!isNullOrEmpty(replicaSetSeeds)) {
 			mongo = new Mongo(replicaSetSeeds, mongoOptions);
 		} else {
-			String mongoHost = host != null ? host : defaultOptions.getHost();
+			String mongoHost = StringUtils.hasText(host) ? host : defaultOptions.getHost();
 			mongo = port != null ? new Mongo(new ServerAddress(mongoHost, port), mongoOptions) : new Mongo(mongoHost,
 					mongoOptions);
 		}
@@ -147,6 +178,10 @@ public class MongoFactoryBean implements FactoryBean<Mongo>, InitializingBean, D
 		this.mongo = mongo;
 	}
 
+	private boolean isNullOrEmpty(Collection<?> elements) {
+		return elements == null || elements.isEmpty();
+	}
+
 	/* 
 	 * (non-Javadoc)
 	 * @see org.springframework.beans.factory.DisposableBean#destroy()

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

@@ -19,6 +19,9 @@ import java.util.Collection;
 import java.util.List;
 import java.util.Set;
 
+import org.springframework.data.mongodb.core.aggregation.Aggregation;
+import org.springframework.data.mongodb.core.aggregation.AggregationResults;
+import org.springframework.data.mongodb.core.aggregation.TypedAggregation;
 import org.springframework.data.mongodb.core.convert.MongoConverter;
 import org.springframework.data.mongodb.core.geo.GeoResult;
 import org.springframework.data.mongodb.core.geo.GeoResults;
@@ -45,6 +48,8 @@ import com.mongodb.WriteResult;
  * @author Thomas Risberg
  * @author Mark Pollack
  * @author Oliver Gierke
+ * @author Tobias Trelle
+ * @author Chuong Ngo
  */
 public interface MongoOperations {
 
@@ -247,7 +252,7 @@ public interface MongoOperations {
 	 * Query for a list 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 SimpleMongoConverter will be used.
+	 * configured otherwise, an instance of 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.
@@ -261,7 +266,7 @@ public interface MongoOperations {
 	 * Query for a list 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 SimpleMongoConverter will be used.
+	 * configured otherwise, an instance of 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.
@@ -301,6 +306,57 @@ public interface MongoOperations {
 	 */
 	<T> GroupByResults<T> group(Criteria criteria, String inputCollectionName, GroupBy groupBy, Class<T> entityClass);
 
+	/**
+	 * Execute an aggregation operation. The raw results will be mapped to the given entity class. The name of the
+	 * inputCollection is derived from the inputType of the aggregation.
+	 * 
+	 * @param aggregation The {@link TypedAggregation} specification holding the aggregation operations, must not be
+	 *          {@literal null}.
+	 * @param collectionName The name of the input collection to use for the aggreation.
+	 * @param outputType The parameterized type of the returned list, must not be {@literal null}.
+	 * @return The results of the aggregation operation.
+	 * @since 1.3
+	 */
+	<O> AggregationResults<O> aggregate(TypedAggregation<?> aggregation, String collectionName, Class<O> outputType);
+
+	/**
+	 * Execute an aggregation operation. The raw results will be mapped to the given entity class. The name of the
+	 * inputCollection is derived from the inputType of the aggregation.
+	 * 
+	 * @param aggregation The {@link TypedAggregation} specification holding the aggregation operations, must not be
+	 *          {@literal null}.
+	 * @param outputType The parameterized type of the returned list, must not be {@literal null}.
+	 * @return The results of the aggregation operation.
+	 * @since 1.3
+	 */
+	<O> AggregationResults<O> aggregate(TypedAggregation<?> aggregation, Class<O> outputType);
+
+	/**
+	 * Execute an aggregation operation. The raw results will be mapped to the given entity class.
+	 * 
+	 * @param aggregation The {@link Aggregation} specification holding the aggregation operations, must not be
+	 *          {@literal null}.
+	 * @param inputType the inputType where the aggregation operation will read from, must not be {@literal null} or
+	 *          empty.
+	 * @param outputType The parameterized type of the returned list, must not be {@literal null}.
+	 * @return The results of the aggregation operation.
+	 * @since 1.3
+	 */
+	<O> AggregationResults<O> aggregate(Aggregation aggregation, Class<?> inputType, Class<O> outputType);
+
+	/**
+	 * Execute an aggregation operation. The raw results will be mapped to the given entity class.
+	 * 
+	 * @param aggregation The {@link Aggregation} specification holding the aggregation operations, must not be
+	 *          {@literal null}.
+	 * @param collectionName the collection where the aggregation operation will read from, must not be {@literal null} or
+	 *          empty.
+	 * @param outputType The parameterized type of the returned list, must not be {@literal null}.
+	 * @return The results of the aggregation operation.
+	 * @since 1.3
+	 */
+	<O> AggregationResults<O> aggregate(Aggregation aggregation, String collectionName, Class<O> outputType);
+
 	/**
 	 * Execute a map-reduce operation. The map-reduce operation will be formed with an output type of INLINE
 	 * 
@@ -382,7 +438,7 @@ public interface MongoOperations {
 	 * specified type.
 	 * <p/>
 	 * The object is converted from the MongoDB native representation using an instance of {@see MongoConverter}. Unless
-	 * configured otherwise, an instance of SimpleMongoConverter will be used.
+	 * configured otherwise, an instance of 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}.
@@ -399,7 +455,7 @@ public interface MongoOperations {
 	 * type.
 	 * <p/>
 	 * The object is converted from the MongoDB native representation using an instance of {@see MongoConverter}. Unless
-	 * configured otherwise, an instance of SimpleMongoConverter will be used.
+	 * configured otherwise, an instance of 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}.
@@ -422,7 +478,7 @@ public interface MongoOperations {
 	 * Map the results of an ad-hoc query on the collection for the entity class to a List 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 SimpleMongoConverter will be used.
+	 * configured otherwise, an instance of 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}.
@@ -438,7 +494,7 @@ public interface MongoOperations {
 	 * Map the results of an ad-hoc query on the specified collection to a List 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 SimpleMongoConverter will be used.
+	 * configured otherwise, an instance of 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}.
@@ -504,7 +560,7 @@ public interface MongoOperations {
 	 * 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 SimpleMongoConverter will be used.
+	 * configured otherwise, an instance of 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}.
@@ -557,7 +613,7 @@ public interface MongoOperations {
 	 * 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 SimpleMongoConverter will be used.
+	 * configured otherwise, an instance of 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.
 	 * 
@@ -595,7 +651,7 @@ public interface MongoOperations {
 	 * 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 SimpleMongoConverter will be used.
+	 * configured otherwise, an instance of 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
@@ -612,7 +668,7 @@ public interface MongoOperations {
 	 * 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 SimpleMongoConverter will be used.
+	 * configured otherwise, an instance of 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
@@ -648,6 +704,18 @@ public interface MongoOperations {
 	 */
 	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
+	 * 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.
+	 */
+	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
 	 * the provided update document.
@@ -672,6 +740,19 @@ public interface MongoOperations {
 	 */
 	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
+	 * 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.
+	 */
+	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
 	 * with the provided updated document.
@@ -696,6 +777,19 @@ public interface MongoOperations {
 	 */
 	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
+	 * 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.
+	 */
+	WriteResult updateMulti(final Query query, final Update update, Class<?> entityClass, String collectionName);
+
 	/**
 	 * Remove the given object from the collection by id.
 	 * 

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2011 the original author or authors.
+ * Copyright 2010-2013 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.
@@ -15,129 +15,91 @@
  */
 package org.springframework.data.mongodb.core;
 
-import com.mongodb.MongoOptions;
+import javax.net.ssl.SSLSocketFactory;
 
 import org.springframework.beans.factory.FactoryBean;
 import org.springframework.beans.factory.InitializingBean;
 
+import com.mongodb.MongoOptions;
+
 /**
- * A factory bean for construction of a MongoOptions instance
+ * A factory bean for construction of a {@link MongoOptions} instance.
  * 
  * @author Graeme Rocher
- * @Author Mark Pollack
+ * @author Mark Pollack
+ * @author Mike Saavedra
+ * @author Thomas Darimont
  */
 public class MongoOptionsFactoryBean implements FactoryBean<MongoOptions>, InitializingBean {
 
-	private static final MongoOptions MONGO_OPTIONS = new MongoOptions();
-	/**
-	 * number of connections allowed per host will block if run out
-	 */
+	@SuppressWarnings("deprecation")//
+	private final MongoOptions MONGO_OPTIONS = new MongoOptions();
+
 	private int connectionsPerHost = MONGO_OPTIONS.connectionsPerHost;
 
-	/**
-	 * multiplier for connectionsPerHost for # of threads that can block if connectionsPerHost is 10, and
-	 * threadsAllowedToBlockForConnectionMultiplier is 5, then 50 threads can block more than that and an exception will
-	 * be throw
-	 */
 	private int threadsAllowedToBlockForConnectionMultiplier = MONGO_OPTIONS.threadsAllowedToBlockForConnectionMultiplier;
-
-	/**
-	 * max wait time of a blocking thread for a connection
-	 */
 	private int maxWaitTime = MONGO_OPTIONS.maxWaitTime;
-
-	/**
-	 * connect timeout in milliseconds. 0 is default and infinite
-	 */
 	private int connectTimeout = MONGO_OPTIONS.connectTimeout;
-
-	/**
-	 * socket timeout. 0 is default and infinite
-	 */
 	private int socketTimeout = MONGO_OPTIONS.socketTimeout;
-
-	/**
-	 * This controls whether or not to have socket keep alive turned on (SO_KEEPALIVE).
-	 * 
-	 * defaults to false
-	 */
-	public boolean socketKeepAlive = MONGO_OPTIONS.socketKeepAlive;
-
-	/**
-	 * this controls whether or not on a connect, the system retries automatically
-	 */
+	private boolean socketKeepAlive = MONGO_OPTIONS.socketKeepAlive;
 	private boolean autoConnectRetry = MONGO_OPTIONS.autoConnectRetry;
-
 	private long maxAutoConnectRetryTime = MONGO_OPTIONS.maxAutoConnectRetryTime;
-
-	/**
-	 * This specifies the number of servers to wait for on the write operation, and exception raising behavior.
-	 * 
-	 * Defaults to 0.
-	 */
 	private int writeNumber;
-
-	/**
-	 * This controls timeout for write operations in milliseconds.
-	 * 
-	 * Defaults to 0 (indefinite). Greater than zero is number of milliseconds to wait.
-	 */
 	private int writeTimeout;
-
-	/**
-	 * This controls whether or not to fsync.
-	 * 
-	 * Defaults to false.
-	 */
 	private boolean writeFsync;
+	@SuppressWarnings("deprecation") private boolean slaveOk = MONGO_OPTIONS.slaveOk;
+	private boolean ssl;
+	private SSLSocketFactory sslSocketFactory;
 
 	/**
-	 * Specifies if the driver is allowed to read from secondaries or slaves.
+	 * Configures the maximum number of connections allowed per host until we will block.
 	 * 
-	 * Defaults to false
-	 */
-	@SuppressWarnings("deprecation")
-	private boolean slaveOk = MONGO_OPTIONS.slaveOk;
-
-	/**
-	 * number of connections allowed per host will block if run out
+	 * @param connectionsPerHost
 	 */
 	public void setConnectionsPerHost(int connectionsPerHost) {
 		this.connectionsPerHost = connectionsPerHost;
 	}
 
 	/**
-	 * multiplier for connectionsPerHost for # of threads that can block if connectionsPerHost is 10, and
-	 * threadsAllowedToBlockForConnectionMultiplier is 5, then 50 threads can block more than that and an exception will
-	 * be throw
+	 * A multiplier for connectionsPerHost for # of threads that can block a connection. If connectionsPerHost is 10, and
+	 * threadsAllowedToBlockForConnectionMultiplier is 5, then 50 threads can block. If more threads try to block an
+	 * exception will be thrown.
+	 * 
+	 * @param threadsAllowedToBlockForConnectionMultiplier
 	 */
 	public void setThreadsAllowedToBlockForConnectionMultiplier(int threadsAllowedToBlockForConnectionMultiplier) {
 		this.threadsAllowedToBlockForConnectionMultiplier = threadsAllowedToBlockForConnectionMultiplier;
 	}
 
 	/**
-	 * max wait time of a blocking thread for a connection
+	 * Max wait time of a blocking thread for a connection.
+	 * 
+	 * @param maxWaitTime
 	 */
 	public void setMaxWaitTime(int maxWaitTime) {
 		this.maxWaitTime = maxWaitTime;
 	}
 
 	/**
-	 * connect timeout in milliseconds. 0 is default and infinite
+	 * Configures the connect timeout in milliseconds. Defaults to 0 (infinite time).
+	 * 
+	 * @param connectTimeout
 	 */
 	public void setConnectTimeout(int connectTimeout) {
 		this.connectTimeout = connectTimeout;
 	}
 
 	/**
-	 * socket timeout. 0 is default and infinite
+	 * Configures the socket timeout. Defaults to 0 (infinite time).
+	 * 
+	 * @param socketTimeout
 	 */
 	public void setSocketTimeout(int socketTimeout) {
 		this.socketTimeout = socketTimeout;
 	}
 
 	/**
-	 * This controls whether or not to have socket keep alive
+	 * Configures whether or not to have socket keep alive turned on (SO_KEEPALIVE). Defaults to {@literal false}.
 	 * 
 	 * @param socketKeepAlive
 	 */
@@ -152,7 +114,7 @@ public class MongoOptionsFactoryBean implements FactoryBean<MongoOptions>, Initi
 	 * <li>-1 = don't even report network errors</li>
 	 * <li>0 = default, don't call getLastError by default</li>
 	 * <li>1 = basic, call getLastError, but don't wait for slaves</li>
-	 * <li>2+= wait for slaves</li>
+	 * <li>2 += wait for slaves</li>
 	 * </ul>
 	 * 
 	 * @param writeNumber the number of servers to wait for on the write operation, and exception raising behavior.
@@ -162,33 +124,33 @@ public class MongoOptionsFactoryBean implements FactoryBean<MongoOptions>, Initi
 	}
 
 	/**
-	 * This controls timeout for write operations in milliseconds. The 'wtimeout' option to the getlasterror command.
+	 * Configures the timeout for write operations in milliseconds. This defaults to {@literal 0} (indefinite).
 	 * 
-	 * @param writeTimeout Defaults to 0 (indefinite). Greater than zero is number of milliseconds to wait.
+	 * @param writeTimeout
 	 */
 	public void setWriteTimeout(int writeTimeout) {
 		this.writeTimeout = writeTimeout;
 	}
 
 	/**
-	 * This controls whether or not to fsync. The 'fsync' option to the getlasterror command. Defaults to false.
+	 * Configures whether or not to fsync. The 'fsync' option to the getlasterror command. Defaults to {@literal false}.
 	 * 
-	 * @param writeFsync to fsync on write (true), otherwise false.
+	 * @param writeFsync to fsync on <code>write (true)<code>, otherwise {@literal false}.
 	 */
 	public void setWriteFsync(boolean writeFsync) {
 		this.writeFsync = writeFsync;
 	}
 
 	/**
-	 * this controls whether or not on a connect, the system retries automatically
+	 * Configures whether or not the system retries automatically on a failed connect. This defaults to {@literal false}.
 	 */
 	public void setAutoConnectRetry(boolean autoConnectRetry) {
 		this.autoConnectRetry = autoConnectRetry;
 	}
 
 	/**
-	 * The maximum amount of time in millisecons to spend retrying to open connection to the same server. Default is 0,
-	 * which means to use the default 15s if autoConnectRetry is on.
+	 * Configures the maximum amount of time in millisecons to spend retrying to open connection to the same server. This
+	 * defaults to {@literal 0}, which means to use the default {@literal 15s} if {@link #autoConnectRetry} is on.
 	 * 
 	 * @param maxAutoConnectRetryTime the maxAutoConnectRetryTime to set
 	 */
@@ -197,7 +159,7 @@ public class MongoOptionsFactoryBean implements FactoryBean<MongoOptions>, Initi
 	}
 
 	/**
-	 * Specifies if the driver is allowed to read from secondaries or slaves. Defaults to false.
+	 * Specifies if the driver is allowed to read from secondaries or slaves. Defaults to {@literal false}.
 	 * 
 	 * @param slaveOk true if the driver should read from secondaries or slaves.
 	 */
@@ -205,8 +167,39 @@ public class MongoOptionsFactoryBean implements FactoryBean<MongoOptions>, Initi
 		this.slaveOk = slaveOk;
 	}
 
+	/**
+	 * Specifies if the driver should use an SSL connection to Mongo. This defaults to {@literal false}. By default
+	 * {@link SSLSocketFactory#getDefault()} will be used. See {@link #setSslSocketFactory(SSLSocketFactory)} if you want
+	 * to configure a custom factory.
+	 * 
+	 * @param ssl true if the driver should use an SSL connection.
+	 * @see #setSslSocketFactory(SSLSocketFactory)
+	 */
+	public void setSsl(boolean ssl) {
+		this.ssl = ssl;
+	}
+
+	/**
+	 * Specifies the {@link SSLSocketFactory} to use for creating SSL connections to Mongo. Defaults to
+	 * {@link SSLSocketFactory#getDefault()}. Implicitly activates {@link #setSsl(boolean)} if a non-{@literal null} value
+	 * is given.
+	 * 
+	 * @param sslSocketFactory the sslSocketFactory to use.
+	 * @see #setSsl(boolean)
+	 */
+	public void setSslSocketFactory(SSLSocketFactory sslSocketFactory) {
+
+		setSsl(sslSocketFactory != null);
+		this.sslSocketFactory = sslSocketFactory;
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.beans.factory.InitializingBean#afterPropertiesSet()
+	 */
 	@SuppressWarnings("deprecation")
 	public void afterPropertiesSet() {
+
 		MONGO_OPTIONS.connectionsPerHost = connectionsPerHost;
 		MONGO_OPTIONS.threadsAllowedToBlockForConnectionMultiplier = threadsAllowedToBlockForConnectionMultiplier;
 		MONGO_OPTIONS.maxWaitTime = maxWaitTime;
@@ -219,18 +212,32 @@ public class MongoOptionsFactoryBean implements FactoryBean<MongoOptions>, Initi
 		MONGO_OPTIONS.w = writeNumber;
 		MONGO_OPTIONS.wtimeout = writeTimeout;
 		MONGO_OPTIONS.fsync = writeFsync;
+		if (ssl) {
+			MONGO_OPTIONS.setSocketFactory(sslSocketFactory != null ? sslSocketFactory : SSLSocketFactory.getDefault());
+		}
 	}
 
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.beans.factory.FactoryBean#getObject()
+	 */
 	public MongoOptions getObject() {
 		return MONGO_OPTIONS;
 	}
 
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.beans.factory.FactoryBean#getObjectType()
+	 */
 	public Class<?> getObjectType() {
 		return MongoOptions.class;
 	}
 
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.beans.factory.FactoryBean#isSingleton()
+	 */
 	public boolean isSingleton() {
 		return true;
 	}
-
 }

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

@@ -46,6 +46,7 @@ import org.springframework.core.io.ResourceLoader;
 import org.springframework.dao.DataAccessException;
 import org.springframework.dao.InvalidDataAccessApiUsageException;
 import org.springframework.dao.OptimisticLockingFailureException;
+import org.springframework.dao.support.PersistenceExceptionTranslator;
 import org.springframework.data.authentication.UserCredentials;
 import org.springframework.data.convert.EntityReader;
 import org.springframework.data.mapping.PersistentEntity;
@@ -53,10 +54,19 @@ import org.springframework.data.mapping.context.MappingContext;
 import org.springframework.data.mapping.model.BeanWrapper;
 import org.springframework.data.mapping.model.MappingException;
 import org.springframework.data.mongodb.MongoDbFactory;
+import org.springframework.data.mongodb.core.aggregation.Aggregation;
+import org.springframework.data.mongodb.core.aggregation.AggregationOperationContext;
+import org.springframework.data.mongodb.core.aggregation.AggregationResults;
+import org.springframework.data.mongodb.core.aggregation.Fields;
+import org.springframework.data.mongodb.core.aggregation.TypeBasedAggregationOperationContext;
+import org.springframework.data.mongodb.core.aggregation.TypedAggregation;
+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.convert.MongoConverter;
 import org.springframework.data.mongodb.core.convert.MongoWriter;
 import org.springframework.data.mongodb.core.convert.QueryMapper;
+import org.springframework.data.mongodb.core.convert.UpdateMapper;
 import org.springframework.data.mongodb.core.geo.Distance;
 import org.springframework.data.mongodb.core.geo.GeoResult;
 import org.springframework.data.mongodb.core.geo.GeoResults;
@@ -113,6 +123,10 @@ import com.mongodb.util.JSONParseException;
  * @author Oliver Gierke
  * @author Amol Nayak
  * @author Patryk Wasik
+ * @author Tobias Trelle
+ * @author Sebastian Herold
+ * @author Thomas Darimont
+ * @author Chuong Ngo
  */
 public class MongoTemplate implements MongoOperations, ApplicationContextAware {
 
@@ -134,8 +148,9 @@ public class MongoTemplate implements MongoOperations, ApplicationContextAware {
 	private final MongoConverter mongoConverter;
 	private final MappingContext<? extends MongoPersistentEntity<?>, MongoPersistentProperty> mappingContext;
 	private final MongoDbFactory mongoDbFactory;
-	private final MongoExceptionTranslator exceptionTranslator = new MongoExceptionTranslator();
-	private final QueryMapper mapper;
+	private final PersistenceExceptionTranslator exceptionTranslator;
+	private final QueryMapper queryMapper;
+	private final UpdateMapper updateMapper;
 
 	private WriteConcern writeConcern;
 	private WriteConcernResolver writeConcernResolver = DefaultWriteConcernResolver.INSTANCE;
@@ -187,8 +202,10 @@ public class MongoTemplate implements MongoOperations, ApplicationContextAware {
 		Assert.notNull(mongoDbFactory);
 
 		this.mongoDbFactory = mongoDbFactory;
+		this.exceptionTranslator = mongoDbFactory.getExceptionTranslator();
 		this.mongoConverter = mongoConverter == null ? getDefaultMongoConverter(mongoDbFactory) : mongoConverter;
-		this.mapper = new QueryMapper(this.mongoConverter);
+		this.queryMapper = new QueryMapper(this.mongoConverter);
+		this.updateMapper = new UpdateMapper(this.mongoConverter);
 
 		// We always have a mapping context in the converter, whether it's a simple one or not
 		mappingContext = this.mongoConverter.getMappingContext();
@@ -495,7 +512,7 @@ public class MongoTemplate implements MongoOperations, ApplicationContextAware {
 			throw new InvalidDataAccessApiUsageException("Query passed in to exist can't be null");
 		}
 
-		DBObject mappedQuery = mapper.getMappedObject(query.getQueryObject(), getPersistentEntity(entityClass));
+		DBObject mappedQuery = queryMapper.getMappedObject(query.getQueryObject(), getPersistentEntity(entityClass));
 		return execute(collectionName, new FindCallback(mappedQuery)).hasNext();
 	}
 
@@ -553,8 +570,26 @@ public class MongoTemplate implements MongoOperations, ApplicationContextAware {
 				mongoConverter, entityClass), near.getMetric());
 		List<GeoResult<T>> result = new ArrayList<GeoResult<T>>(results.size());
 
+		int index = 0;
+		int elementsToSkip = near.getSkip() != null ? near.getSkip() : 0;
+
 		for (Object element : results) {
-			result.add(callback.doWith((DBObject) element));
+
+			/*
+			 * As MongoDB currently (2.4.4) doesn't support the skipping of elements in near queries
+			 * we skip the elements ourselves to avoid at least the document 2 object mapping overhead.
+			 * 
+			 * @see https://jira.mongodb.org/browse/SERVER-3925
+			 */
+			if (index >= elementsToSkip) {
+				result.add(callback.doWith((DBObject) element));
+			}
+			index++;
+		}
+
+		if (elementsToSkip > 0) {
+			// as we skipped some elements we have to calculate the averageDistance ourselves:
+			return new GeoResults<T>(result, near.getMetric());
 		}
 
 		DBObject stats = (DBObject) commandResult.get("stats");
@@ -604,7 +639,7 @@ public class MongoTemplate implements MongoOperations, ApplicationContextAware {
 	private long count(Query query, Class<?> entityClass, String collectionName) {
 
 		Assert.hasText(collectionName);
-		final DBObject dbObject = query == null ? null : mapper.getMappedObject(query.getQueryObject(),
+		final DBObject dbObject = query == null ? null : queryMapper.getMappedObject(query.getQueryObject(),
 				entityClass == null ? null : mappingContext.getPersistentEntity(entityClass));
 
 		return execute(collectionName, new CollectionCallback<Long>() {
@@ -669,10 +704,9 @@ public class MongoTemplate implements MongoOperations, ApplicationContextAware {
 
 		initializeVersionProperty(objectToSave);
 
-		BasicDBObject dbDoc = new BasicDBObject();
-
 		maybeEmitEvent(new BeforeConvertEvent<T>(objectToSave));
-		writer.write(objectToSave, dbDoc);
+
+		DBObject dbDoc = toDbObject(objectToSave, writer);
 
 		maybeEmitEvent(new BeforeSaveEvent<T>(objectToSave, dbDoc));
 		Object id = insertDBObject(collectionName, dbDoc, objectToSave.getClass());
@@ -681,6 +715,26 @@ public class MongoTemplate implements MongoOperations, ApplicationContextAware {
 		maybeEmitEvent(new AfterSaveEvent<T>(objectToSave, dbDoc));
 	}
 
+	/**
+	 * @param objectToSave
+	 * @param writer
+	 * @return
+	 */
+	private <T> DBObject toDbObject(T objectToSave, MongoWriter<T> writer) {
+
+		if (!(objectToSave instanceof String)) {
+			DBObject dbDoc = new BasicDBObject();
+			writer.write(objectToSave, dbDoc);
+			return dbDoc;
+		} else {
+			try {
+				return (DBObject) JSON.parse((String) objectToSave);
+			} catch (JSONParseException e) {
+				throw new MappingException("Could not parse given String to save into a JSON document!", e);
+			}
+		}
+	}
+
 	private void initializeVersionProperty(Object entity) {
 
 		MongoPersistentEntity<?> mongoPersistentEntity = getPersistentEntity(entity.getClass());
@@ -820,19 +874,9 @@ public class MongoTemplate implements MongoOperations, ApplicationContextAware {
 
 		assertUpdateableIdIfNotSet(objectToSave);
 
-		DBObject dbDoc = new BasicDBObject();
-
 		maybeEmitEvent(new BeforeConvertEvent<T>(objectToSave));
 
-		if (!(objectToSave instanceof String)) {
-			writer.write(objectToSave, dbDoc);
-		} else {
-			try {
-				dbDoc = (DBObject) JSON.parse((String) objectToSave);
-			} catch (JSONParseException e) {
-				throw new MappingException("Could not parse given String to save into a JSON document!", e);
-			}
-		}
+		DBObject dbDoc = toDbObject(objectToSave, writer);
 
 		maybeEmitEvent(new BeforeSaveEvent<T>(objectToSave, dbDoc));
 		Object id = saveDBObject(collectionName, dbDoc, objectToSave.getClass());
@@ -916,6 +960,10 @@ public class MongoTemplate implements MongoOperations, ApplicationContextAware {
 		return doUpdate(collectionName, query, update, null, true, false);
 	}
 
+	public WriteResult upsert(Query query, Update update, Class<?> entityClass, String collectionName) {
+		return doUpdate(collectionName, query, update, entityClass, true, false);
+	}
+
 	public WriteResult updateFirst(Query query, Update update, Class<?> entityClass) {
 		return doUpdate(determineCollectionName(entityClass), query, update, entityClass, false, false);
 	}
@@ -924,6 +972,10 @@ public class MongoTemplate implements MongoOperations, ApplicationContextAware {
 		return doUpdate(collectionName, query, update, null, false, false);
 	}
 
+	public WriteResult updateFirst(Query query, Update update, Class<?> entityClass, String collectionName) {
+		return doUpdate(collectionName, query, update, entityClass, false, false);
+	}
+
 	public WriteResult updateMulti(Query query, Update update, Class<?> entityClass) {
 		return doUpdate(determineCollectionName(entityClass), query, update, entityClass, false, true);
 	}
@@ -932,6 +984,10 @@ public class MongoTemplate implements MongoOperations, ApplicationContextAware {
 		return doUpdate(collectionName, query, update, null, false, true);
 	}
 
+	public WriteResult updateMulti(final Query query, final Update update, Class<?> entityClass, String collectionName) {
+		return doUpdate(collectionName, query, update, entityClass, false, true);
+	}
+
 	protected WriteResult doUpdate(final String collectionName, final Query query, final Update update,
 			final Class<?> entityClass, final boolean upsert, final boolean multi) {
 
@@ -940,10 +996,10 @@ public class MongoTemplate implements MongoOperations, ApplicationContextAware {
 
 				MongoPersistentEntity<?> entity = entityClass == null ? null : getPersistentEntity(entityClass);
 
-				DBObject queryObj = query == null ? new BasicDBObject()
-						: mapper.getMappedObject(query.getQueryObject(), entity);
-				DBObject updateObj = update == null ? new BasicDBObject() : mapper.getMappedObject(update.getUpdateObject(),
+				DBObject queryObj = query == null ? new BasicDBObject() : queryMapper.getMappedObject(query.getQueryObject(),
 						entity);
+				DBObject updateObj = update == null ? new BasicDBObject() : updateMapper.getMappedObject(
+						update.getUpdateObject(), entity);
 
 				if (LOGGER.isDebugEnabled()) {
 					LOGGER.debug("Calling update using query: " + queryObj + " and update: " + updateObj + " in collection: "
@@ -1061,7 +1117,7 @@ public class MongoTemplate implements MongoOperations, ApplicationContextAware {
 
 				maybeEmitEvent(new BeforeDeleteEvent<T>(queryObject, entityClass));
 
-				DBObject dboq = mapper.getMappedObject(queryObject, entity);
+				DBObject dboq = queryMapper.getMappedObject(queryObject, entity);
 
 				MongoAction mongoAction = new MongoAction(writeConcern, MongoActionOperation.REMOVE, collectionName,
 						entityClass, null, queryObject);
@@ -1156,7 +1212,7 @@ public class MongoTemplate implements MongoOperations, ApplicationContextAware {
 		if (criteria == null) {
 			dbo.put("cond", null);
 		} else {
-			dbo.put("cond", mapper.getMappedObject(criteria.getCriteriaObject(), null));
+			dbo.put("cond", queryMapper.getMappedObject(criteria.getCriteriaObject(), null));
 		}
 		// If initial document was a JavaScript string, potentially loaded by Spring's Resource abstraction, load it and
 		// convert to DBObject
@@ -1205,6 +1261,64 @@ public class MongoTemplate implements MongoOperations, ApplicationContextAware {
 
 	}
 
+	@Override
+	public <O> AggregationResults<O> aggregate(TypedAggregation<?> aggregation, Class<O> outputType) {
+		return aggregate(aggregation, determineCollectionName(aggregation.getInputType()), outputType);
+	}
+
+	@Override
+	public <O> AggregationResults<O> aggregate(TypedAggregation<?> aggregation, String inputCollectionName,
+			Class<O> outputType) {
+
+		Assert.notNull(aggregation, "Aggregation pipeline must not be null!");
+
+		AggregationOperationContext context = new TypeBasedAggregationOperationContext(aggregation.getInputType(),
+				mappingContext, queryMapper);
+		return aggregate(aggregation, inputCollectionName, outputType, context);
+	}
+
+	@Override
+	public <O> AggregationResults<O> aggregate(Aggregation aggregation, Class<?> inputType, Class<O> outputType) {
+
+		return aggregate(aggregation, determineCollectionName(inputType), outputType,
+				new TypeBasedAggregationOperationContext(inputType, mappingContext, queryMapper));
+	}
+
+	@Override
+	public <O> AggregationResults<O> aggregate(Aggregation aggregation, String collectionName, Class<O> outputType) {
+		return aggregate(aggregation, collectionName, outputType, null);
+	}
+
+	protected <O> AggregationResults<O> aggregate(Aggregation aggregation, String collectionName, Class<O> outputType,
+			AggregationOperationContext context) {
+
+		Assert.hasText(collectionName, "Collection name must not be null or empty!");
+		Assert.notNull(aggregation, "Aggregation pipeline must not be null!");
+		Assert.notNull(outputType, "Output type must not be null!");
+
+		AggregationOperationContext rootContext = context == null ? Aggregation.DEFAULT_CONTEXT : context;
+		DBObject command = aggregation.toDbObject(collectionName, rootContext);
+
+		if (LOGGER.isDebugEnabled()) {
+			LOGGER.debug("Executing aggregation: {}", serializeToJsonSafely(command));
+		}
+
+		CommandResult commandResult = executeCommand(command);
+		handleCommandError(commandResult, command);
+
+		// map results
+		@SuppressWarnings("unchecked")
+		Iterable<DBObject> resultSet = (Iterable<DBObject>) commandResult.get("result");
+		List<O> mappedResults = new ArrayList<O>();
+		DbObjectCallback<O> callback = new UnwrapAndReadDbObjectCallback<O>(mongoConverter, outputType);
+
+		for (DBObject dbObject : resultSet) {
+			mappedResults.add(callback.doWith(dbObject));
+		}
+
+		return new AggregationResults<O>(mappedResults, commandResult);
+	}
+
 	protected String replaceWithResourceIfNecessary(String function) {
 
 		String func = function;
@@ -1313,57 +1427,28 @@ public class MongoTemplate implements MongoOperations, ApplicationContextAware {
 	}
 
 	/**
-	 * Map the results of an ad-hoc query on the default MongoDB collection to an object using the template's converter
-	 * <p/>
-	 * The query document is specified as a standard DBObject and so is the fields specification.
+	 * Map the results of an ad-hoc query on the default MongoDB collection to an object using the template's converter.
+	 * The query document is specified as a standard {@link DBObject} and so is the fields specification.
 	 * 
-	 * @param collectionName name of the collection to retrieve the objects from
-	 * @param query the query document that specifies the criteria used to find a record
-	 * @param fields the document that specifies the fields to be returned
+	 * @param collectionName name of the collection to retrieve the objects from.
+	 * @param query the query document that specifies the criteria used to find a record.
+	 * @param fields the document that specifies the fields to be returned.
 	 * @param entityClass the parameterized type of the returned list.
-	 * @return the List of converted objects.
+	 * @return the {@link List} of converted objects.
 	 */
 	protected <T> T doFindOne(String collectionName, DBObject query, DBObject fields, Class<T> entityClass) {
-		EntityReader<? super T, DBObject> readerToUse = this.mongoConverter;
-		MongoPersistentEntity<?> entity = mappingContext.getPersistentEntity(entityClass);
-		DBObject mappedQuery = mapper.getMappedObject(query, entity);
-
-		return executeFindOneInternal(new FindOneCallback(mappedQuery, fields), new ReadDbObjectCallback<T>(readerToUse,
-				entityClass), collectionName);
-	}
-
-	/**
-	 * Map the results of an ad-hoc query on the default MongoDB collection to a List of the specified type. The object is
-	 * converted from the MongoDB native representation using an instance of {@see MongoConverter}. Unless configured
-	 * otherwise, an instance of SimpleMongoConverter will be used. The query document is specified as a standard DBObject
-	 * and so is the fields specification. Can be overridden by subclasses.
-	 * 
-	 * @param collectionName name of the collection to retrieve the objects from
-	 * @param query the query document that specifies the criteria used to find a record
-	 * @param fields the document that specifies the fields to be returned
-	 * @param entityClass the parameterized type of the returned list.
-	 * @param preparer allows for customization of the DBCursor used when iterating over the result set, (apply limits,
-	 *          skips and so on).
-	 * @return the List of converted objects.
-	 */
-	protected <T> List<T> doFind(String collectionName, DBObject query, DBObject fields, Class<T> entityClass,
-			CursorPreparer preparer) {
-		return doFind(collectionName, query, fields, entityClass, preparer, new ReadDbObjectCallback<T>(mongoConverter,
-				entityClass));
-	}
-
-	protected <S, T> List<T> doFind(String collectionName, DBObject query, DBObject fields, Class<S> entityClass,
-			CursorPreparer preparer, DbObjectCallback<T> objectCallback) {
 
 		MongoPersistentEntity<?> entity = mappingContext.getPersistentEntity(entityClass);
+		DBObject mappedQuery = queryMapper.getMappedObject(query, entity);
+		DBObject mappedFields = fields == null ? null : queryMapper.getMappedObject(fields, entity);
 
 		if (LOGGER.isDebugEnabled()) {
-			LOGGER.debug(String.format("find using query: %s fields: %s for class: %s in collection: %s",
-					serializeToJsonSafely(query), fields, entityClass, collectionName));
+			LOGGER.debug(String.format("findOne using query: %s fields: %s for class: %s in collection: %s",
+					serializeToJsonSafely(query), mappedFields, entityClass, collectionName));
 		}
 
-		return executeFindMultiInternal(new FindCallback(mapper.getMappedObject(query, entity), fields), preparer,
-				objectCallback, collectionName);
+		return executeFindOneInternal(new FindOneCallback(mappedQuery, mappedFields), new ReadDbObjectCallback<T>(
+				this.mongoConverter, entityClass), collectionName);
 	}
 
 	/**
@@ -1377,14 +1462,43 @@ public class MongoTemplate implements MongoOperations, ApplicationContextAware {
 	 * @return the List of converted objects.
 	 */
 	protected <T> List<T> doFind(String collectionName, DBObject query, DBObject fields, Class<T> entityClass) {
-		if (LOGGER.isDebugEnabled()) {
-			LOGGER.debug("find using query: " + query + " fields: " + fields + " for class: " + entityClass
-					+ " in collection: " + collectionName);
-		}
-		EntityReader<? super T, DBObject> readerToUse = this.mongoConverter;
+		return doFind(collectionName, query, fields, entityClass, null, new ReadDbObjectCallback<T>(this.mongoConverter,
+				entityClass));
+	}
+
+	/**
+	 * Map the results of an ad-hoc query on the default MongoDB collection to a List of the specified type. The object is
+	 * converted from the MongoDB native representation using an instance of {@see MongoConverter}. The query document is
+	 * specified as a standard DBObject and so is the fields specification.
+	 * 
+	 * @param collectionName name of the collection to retrieve the objects from.
+	 * @param query the query document that specifies the criteria used to find a record.
+	 * @param fields the document that specifies the fields to be returned.
+	 * @param entityClass the parameterized type of the returned list.
+	 * @param preparer allows for customization of the {@link DBCursor} used when iterating over the result set, (apply
+	 *          limits, skips and so on).
+	 * @return the {@link List} of converted objects.
+	 */
+	protected <T> List<T> doFind(String collectionName, DBObject query, DBObject fields, Class<T> entityClass,
+			CursorPreparer preparer) {
+		return doFind(collectionName, query, fields, entityClass, preparer, new ReadDbObjectCallback<T>(mongoConverter,
+				entityClass));
+	}
+
+	protected <S, T> List<T> doFind(String collectionName, DBObject query, DBObject fields, Class<S> entityClass,
+			CursorPreparer preparer, DbObjectCallback<T> objectCallback) {
+
 		MongoPersistentEntity<?> entity = mappingContext.getPersistentEntity(entityClass);
-		return executeFindMultiInternal(new FindCallback(mapper.getMappedObject(query, entity), fields), null,
-				new ReadDbObjectCallback<T>(readerToUse, entityClass), collectionName);
+		DBObject mappedFields = fields == null ? null : queryMapper.getMappedObject(fields, entity);
+		DBObject mappedQuery = queryMapper.getMappedObject(query, entity);
+
+		if (LOGGER.isDebugEnabled()) {
+			LOGGER.debug(String.format("find using query: %s fields: %s for class: %s in collection: %s",
+					serializeToJsonSafely(query), mappedFields, entityClass, collectionName));
+		}
+
+		return executeFindMultiInternal(new FindCallback(mappedQuery, mappedFields), preparer, objectCallback,
+				collectionName);
 	}
 
 	protected DBObject convertToDbObject(CollectionOptions collectionOptions) {
@@ -1422,7 +1536,7 @@ public class MongoTemplate implements MongoOperations, ApplicationContextAware {
 					+ entityClass + " in collection: " + collectionName);
 		}
 		MongoPersistentEntity<?> entity = mappingContext.getPersistentEntity(entityClass);
-		return executeFindOneInternal(new FindAndRemoveCallback(mapper.getMappedObject(query, entity), fields, sort),
+		return executeFindOneInternal(new FindAndRemoveCallback(queryMapper.getMappedObject(query, entity), fields, sort),
 				new ReadDbObjectCallback<T>(readerToUse, entityClass), collectionName);
 	}
 
@@ -1437,19 +1551,15 @@ public class MongoTemplate implements MongoOperations, ApplicationContextAware {
 
 		MongoPersistentEntity<?> entity = mappingContext.getPersistentEntity(entityClass);
 
-		DBObject updateObj = update.getUpdateObject();
-		for (String key : updateObj.keySet()) {
-			updateObj.put(key, mongoConverter.convertToMongoType(updateObj.get(key)));
-		}
-
-		DBObject mappedQuery = mapper.getMappedObject(query, entity);
+		DBObject mappedUpdate = queryMapper.getMappedObject(update.getUpdateObject(), entity);
+		DBObject mappedQuery = queryMapper.getMappedObject(query, entity);
 
 		if (LOGGER.isDebugEnabled()) {
 			LOGGER.debug("findAndModify using query: " + mappedQuery + " fields: " + fields + " sort: " + sort
-					+ " for class: " + entityClass + " and update: " + updateObj + " in collection: " + collectionName);
+					+ " for class: " + entityClass + " and update: " + mappedUpdate + " in collection: " + collectionName);
 		}
 
-		return executeFindOneInternal(new FindAndModifyCallback(mappedQuery, fields, sort, updateObj, options),
+		return executeFindOneInternal(new FindAndModifyCallback(mappedQuery, fields, sort, mappedUpdate, options),
 				new ReadDbObjectCallback<T>(readerToUse, entityClass), collectionName);
 	}
 
@@ -1717,7 +1827,9 @@ public class MongoTemplate implements MongoOperations, ApplicationContextAware {
 	}
 
 	private static final MongoConverter getDefaultMongoConverter(MongoDbFactory factory) {
-		MappingMongoConverter converter = new MappingMongoConverter(factory, new MongoMappingContext());
+
+		DbRefResolver dbRefResolver = new DefaultDbRefResolver(factory);
+		MappingMongoConverter converter = new MappingMongoConverter(dbRefResolver, new MongoMappingContext());
 		converter.afterPropertiesSet();
 		return converter;
 	}
@@ -1874,6 +1986,35 @@ public class MongoTemplate implements MongoOperations, ApplicationContextAware {
 		}
 	}
 
+	class UnwrapAndReadDbObjectCallback<T> extends ReadDbObjectCallback<T> {
+
+		public UnwrapAndReadDbObjectCallback(EntityReader<? super T, DBObject> reader, Class<T> type) {
+			super(reader, type);
+		}
+
+		@Override
+		public T doWith(DBObject object) {
+
+			Object idField = object.get(Fields.UNDERSCORE_ID);
+
+			if (!(idField instanceof DBObject)) {
+				return super.doWith(object);
+			}
+
+			DBObject toMap = new BasicDBObject();
+			DBObject nested = (DBObject) idField;
+			toMap.putAll(nested);
+
+			for (String key : object.keySet()) {
+				if (!Fields.UNDERSCORE_ID.equals(key)) {
+					toMap.put(key, object.get(key));
+				}
+			}
+
+			return super.doWith(toMap);
+		}
+	}
+
 	private enum DefaultWriteConcernResolver implements WriteConcernResolver {
 
 		INSTANCE;

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2011-2012 the original author or authors.
+ * Copyright 2011-2013 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.
@@ -19,9 +19,11 @@ 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.authentication.UserCredentials;
 import org.springframework.data.mongodb.MongoDbFactory;
 import org.springframework.util.Assert;
+import org.springframework.util.StringUtils;
 
 import com.mongodb.DB;
 import com.mongodb.Mongo;
@@ -34,6 +36,7 @@ import com.mongodb.WriteConcern;
  * 
  * @author Mark Pollack
  * @author Oliver Gierke
+ * @author Thomas Darimont
  */
 public class SimpleMongoDbFactory implements DisposableBean, MongoDbFactory {
 
@@ -41,6 +44,9 @@ public class SimpleMongoDbFactory implements DisposableBean, MongoDbFactory {
 	private final String databaseName;
 	private final boolean mongoInstanceCreated;
 	private final UserCredentials credentials;
+	private final PersistenceExceptionTranslator exceptionTranslator;
+	private final String authenticationDatabaseName;
+
 	private WriteConcern writeConcern;
 
 	/**
@@ -50,7 +56,7 @@ public class SimpleMongoDbFactory implements DisposableBean, MongoDbFactory {
 	 * @param databaseName database name, not be {@literal null} or empty.
 	 */
 	public SimpleMongoDbFactory(Mongo mongo, String databaseName) {
-		this(mongo, databaseName, UserCredentials.NO_CREDENTIALS, false);
+		this(mongo, databaseName, null);
 	}
 
 	/**
@@ -61,7 +67,20 @@ public class SimpleMongoDbFactory implements DisposableBean, MongoDbFactory {
 	 * @param credentials username and password.
 	 */
 	public SimpleMongoDbFactory(Mongo mongo, String databaseName, UserCredentials credentials) {
-		this(mongo, databaseName, credentials, false);
+		this(mongo, databaseName, credentials, false, null);
+	}
+
+	/**
+	 * Create an instance of SimpleMongoDbFactory given the Mongo instance, database name, and username/password
+	 * 
+	 * @param mongo Mongo instance, must not be {@literal null}.
+	 * @param databaseName Database name, must not be {@literal null} or empty.
+	 * @param credentials username and password.
+	 * @param authenticationDatabaseName the database name to use for authentication
+	 */
+	public SimpleMongoDbFactory(Mongo mongo, String databaseName, UserCredentials credentials,
+			String authenticationDatabaseName) {
+		this(mongo, databaseName, credentials, false, authenticationDatabaseName);
 	}
 
 	/**
@@ -72,12 +91,14 @@ public class SimpleMongoDbFactory implements DisposableBean, MongoDbFactory {
 	 * @throws UnknownHostException
 	 * @see MongoURI
 	 */
+	@SuppressWarnings("deprecation")
 	public SimpleMongoDbFactory(MongoURI uri) throws MongoException, UnknownHostException {
-		this(new Mongo(uri), uri.getDatabase(), new UserCredentials(uri.getUsername(), parseChars(uri.getPassword())), true);
+		this(new Mongo(uri), uri.getDatabase(), new UserCredentials(uri.getUsername(), parseChars(uri.getPassword())),
+				true, uri.getDatabase());
 	}
 
 	private SimpleMongoDbFactory(Mongo mongo, String databaseName, UserCredentials credentials,
-			boolean mongoInstanceCreated) {
+			boolean mongoInstanceCreated, String authenticationDatabaseName) {
 
 		Assert.notNull(mongo, "Mongo must not be null");
 		Assert.hasText(databaseName, "Database name must not be empty");
@@ -88,6 +109,12 @@ public class SimpleMongoDbFactory implements DisposableBean, MongoDbFactory {
 		this.databaseName = databaseName;
 		this.mongoInstanceCreated = mongoInstanceCreated;
 		this.credentials = credentials == null ? UserCredentials.NO_CREDENTIALS : credentials;
+		this.exceptionTranslator = new MongoExceptionTranslator();
+		this.authenticationDatabaseName = StringUtils.hasText(authenticationDatabaseName) ? authenticationDatabaseName
+				: databaseName;
+
+		Assert.isTrue(this.authenticationDatabaseName.matches("[\\w-]+"),
+				"Authentication database name must only contain letters, numbers, underscores and dashes!");
 	}
 
 	/**
@@ -115,7 +142,7 @@ public class SimpleMongoDbFactory implements DisposableBean, MongoDbFactory {
 
 		Assert.hasText(dbName, "Database name must not be empty.");
 
-		DB db = MongoDbUtils.getDB(mongo, dbName, credentials);
+		DB db = MongoDbUtils.getDB(mongo, dbName, credentials, authenticationDatabaseName);
 
 		if (writeConcern != null) {
 			db.setWriteConcern(writeConcern);
@@ -138,4 +165,13 @@ public class SimpleMongoDbFactory implements DisposableBean, MongoDbFactory {
 	private static String parseChars(char[] chars) {
 		return chars == null ? null : String.valueOf(chars);
 	}
+
+	/* 
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.MongoDbFactory#getExceptionTranslator()
+	 */
+	@Override
+	public PersistenceExceptionTranslator getExceptionTranslator() {
+		return this.exceptionTranslator;
+	}
 }

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

@@ -0,0 +1,305 @@
+/*
+ * 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.
+ * 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 static org.springframework.data.mongodb.core.aggregation.Fields.*;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+import org.springframework.data.domain.Sort;
+import org.springframework.data.domain.Sort.Direction;
+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.query.Criteria;
+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.
+ * 
+ * @author Tobias Trelle
+ * @author Thomas Darimont
+ * @author Oliver Gierke
+ * @since 1.3
+ */
+public class Aggregation {
+
+	public static final AggregationOperationContext DEFAULT_CONTEXT = new NoOpAggregationOperationContext();
+
+	private final List<AggregationOperation> operations;
+
+	/**
+	 * Creates a new {@link Aggregation} from the given {@link AggregationOperation}s.
+	 * 
+	 * @param operations must not be {@literal null} or empty.
+	 */
+	public static Aggregation newAggregation(List<? extends AggregationOperation> operations) {
+		return newAggregation(operations.toArray(new AggregationOperation[operations.size()]));
+	}
+
+	/**
+	 * Creates a new {@link Aggregation} from the given {@link AggregationOperation}s.
+	 * 
+	 * @param operations must not be {@literal null} or empty.
+	 */
+	public static Aggregation newAggregation(AggregationOperation... operations) {
+		return new Aggregation(operations);
+	}
+
+	/**
+	 * Creates a new {@link TypedAggregation} for the given type and {@link AggregationOperation}s.
+	 * 
+	 * @param type must not be {@literal null}.
+	 * @param operations must not be {@literal null} or empty.
+	 */
+	public static <T> TypedAggregation<T> newAggregation(Class<T> type, List<? extends AggregationOperation> operations) {
+		return newAggregation(type, operations.toArray(new AggregationOperation[operations.size()]));
+	}
+
+	/**
+	 * Creates a new {@link TypedAggregation} for the given type and {@link AggregationOperation}s.
+	 * 
+	 * @param type must not be {@literal null}.
+	 * @param operations must not be {@literal null} or empty.
+	 */
+	public static <T> TypedAggregation<T> newAggregation(Class<T> type, AggregationOperation... operations) {
+		return new TypedAggregation<T>(type, operations);
+	}
+
+	/**
+	 * Creates a new {@link Aggregation} from the given {@link AggregationOperation}s.
+	 * 
+	 * @param aggregationOperations must not be {@literal null} or empty.
+	 */
+	protected Aggregation(AggregationOperation... aggregationOperations) {
+
+		Assert.notNull(aggregationOperations, "AggregationOperations must not be null!");
+		Assert.isTrue(aggregationOperations.length > 0, "At least one AggregationOperation has to be provided");
+
+		this.operations = Arrays.asList(aggregationOperations);
+	}
+
+	/**
+	 * A pointer to the previous {@link AggregationOperation}.
+	 * 
+	 * @return
+	 */
+	public static String previousOperation() {
+		return "_id";
+	}
+
+	/**
+	 * Creates a new {@link ProjectionOperation} including the given fields.
+	 * 
+	 * @param fields must not be {@literal null}.
+	 * @return
+	 */
+	public static ProjectionOperation project(String... fields) {
+		return project(fields(fields));
+	}
+
+	/**
+	 * Creates a new {@link ProjectionOperation} includeing the given {@link Fields}.
+	 * 
+	 * @param fields must not be {@literal null}.
+	 * @return
+	 */
+	public static ProjectionOperation project(Fields fields) {
+		return new ProjectionOperation(fields);
+	}
+
+	/**
+	 * Factory method to create a new {@link UnwindOperation} for the field with the given name.
+	 * 
+	 * @param fieldName must not be {@literal null} or empty.
+	 * @return
+	 */
+	public static UnwindOperation unwind(String field) {
+		return new UnwindOperation(field(field));
+	}
+
+	/**
+	 * Creates a new {@link GroupOperation} for the given fields.
+	 * 
+	 * @param fields must not be {@literal null}.
+	 * @return
+	 */
+	public static GroupOperation group(String... fields) {
+		return group(fields(fields));
+	}
+
+	/**
+	 * Creates a new {@link GroupOperation} for the given {@link Fields}.
+	 * 
+	 * @param fields must not be {@literal null}.
+	 * @return
+	 */
+	public static GroupOperation group(Fields fields) {
+		return new GroupOperation(fields);
+	}
+
+	/**
+	 * Factory method to create a new {@link SortOperation} for the given {@link Sort}.
+	 * 
+	 * @param sort must not be {@literal null}.
+	 * @return
+	 */
+	public static SortOperation sort(Sort sort) {
+		return new SortOperation(sort);
+	}
+
+	/**
+	 * Factory method to create a new {@link SortOperation} for the given sort {@link Direction} and {@code fields}.
+	 * 
+	 * @param direction must not be {@literal null}.
+	 * @param fields must not be {@literal null}.
+	 * @return
+	 */
+	public static SortOperation sort(Direction direction, String... fields) {
+		return new SortOperation(new Sort(direction, fields));
+	}
+
+	/**
+	 * Creates a new {@link SkipOperation} skipping the given number of elements.
+	 * 
+	 * @param elementsToSkip must not be less than zero.
+	 * @return
+	 */
+	public static SkipOperation skip(int elementsToSkip) {
+		return new SkipOperation(elementsToSkip);
+	}
+
+	/**
+	 * Creates a new {@link LimitOperation} limiting the result to the given number of elements.
+	 * 
+	 * @param maxElements must not be less than zero.
+	 * @return
+	 */
+	public static LimitOperation limit(long maxElements) {
+		return new LimitOperation(maxElements);
+	}
+
+	/**
+	 * Creates a new {@link MatchOperation} using the given {@link Criteria}.
+	 * 
+	 * @param criteria must not be {@literal null}.
+	 * @return
+	 */
+	public static MatchOperation match(Criteria criteria) {
+		return new MatchOperation(criteria);
+	}
+
+	/**
+	 * Creates a new {@link Fields} instance for the given field names.
+	 * 
+	 * @see Fields#fields(String...)
+	 * @param fields must not be {@literal null}.
+	 * @return
+	 */
+	public static Fields fields(String... fields) {
+		return Fields.fields(fields);
+	}
+
+	/**
+	 * Creates a new {@link Fields} instance from the given field name and target reference.
+	 * 
+	 * @param name must not be {@literal null} or empty.
+	 * @param target must not be {@literal null} or empty.
+	 * @return
+	 */
+	public static Fields bind(String name, String target) {
+		return Fields.from(field(name, target));
+	}
+
+	/**
+	 * Converts this {@link Aggregation} specification to a {@link DBObject}.
+	 * 
+	 * @param inputCollectionName the name of the input collection
+	 * @return the {@code DBObject} representing this aggregation
+	 */
+	public DBObject toDbObject(String inputCollectionName, AggregationOperationContext rootContext) {
+
+		AggregationOperationContext context = rootContext;
+		List<DBObject> operationDocuments = new ArrayList<DBObject>(operations.size());
+
+		for (AggregationOperation operation : operations) {
+
+			operationDocuments.add(operation.toDBObject(context));
+
+			if (operation instanceof FieldsExposingAggregationOperation) {
+				FieldsExposingAggregationOperation exposedFieldsOperation = (FieldsExposingAggregationOperation) operation;
+				context = new ExposedFieldsAggregationOperationContext(exposedFieldsOperation.getFields());
+			}
+		}
+
+		DBObject command = new BasicDBObject("aggregate", inputCollectionName);
+		command.put("pipeline", operationDocuments);
+
+		return command;
+	}
+
+	/* 
+	 * (non-Javadoc)
+	 * @see java.lang.Object#toString()
+	 */
+	@Override
+	public String toString() {
+		return SerializationUtils
+				.serializeToJsonSafely(toDbObject("__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.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 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));
+		}
+	}
+}

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

@@ -0,0 +1,82 @@
+/*
+ * 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.
+ * 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.AggregationExpressionTransformer.AggregationExpressionTransformationContext;
+import org.springframework.data.mongodb.core.aggregation.ExposedFields.FieldReference;
+import org.springframework.data.mongodb.core.spel.ExpressionNode;
+import org.springframework.data.mongodb.core.spel.ExpressionTransformationContextSupport;
+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
+ */
+interface AggregationExpressionTransformer extends
+		ExpressionTransformer<AggregationExpressionTransformationContext<ExpressionNode>> {
+
+	/**
+	 * A special {@link ExpressionTransformationContextSupport} to be aware of the {@link AggregationOperationContext}.
+	 * 
+	 * @author Oliver Gierke
+	 * @author Thomas Darimont
+	 */
+	public static class AggregationExpressionTransformationContext<T extends ExpressionNode> extends
+			ExpressionTransformationContextSupport<T> {
+
+		private final AggregationOperationContext aggregationContext;
+
+		/**
+		 * Creates an {@link AggregationExpressionTransformationContext}.
+		 * 
+		 * @param currentNode must not be {@literal null}.
+		 * @param parentNode
+		 * @param previousOperationObject
+		 * @param aggregationContext must not be {@literal null}.
+		 */
+		public AggregationExpressionTransformationContext(T currentNode, ExpressionNode parentNode,
+				DBObject previousOperationObject, AggregationOperationContext context) {
+
+			super(currentNode, parentNode, previousOperationObject);
+
+			Assert.notNull(context, "AggregationOperationContext must not be null!");
+			this.aggregationContext = context;
+		}
+
+		/**
+		 * Returns the underlying {@link AggregationOperationContext}.
+		 * 
+		 * @return
+		 */
+		public AggregationOperationContext getAggregationContext() {
+			return aggregationContext;
+		}
+
+		/**
+		 * Returns the {@link FieldReference} for the current {@link ExpressionNode}.
+		 * 
+		 * @return
+		 */
+		public FieldReference getFieldReference() {
+			return aggregationContext.getReference(getCurrentNode().getName());
+		}
+	}
+}

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

@@ -0,0 +1,37 @@
+/*
+ * 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.
+ * 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 com.mongodb.DBObject;
+
+/**
+ * Represents one single operation in an aggregation pipeline.
+ * 
+ * @author Sebastian Herold
+ * @author Thomas Darimont
+ * @author Oliver Gierke
+ * @since 1.3
+ */
+public interface AggregationOperation {
+
+	/**
+	 * Turns the {@link AggregationOperation} into a {@link DBObject} by using the given
+	 * {@link AggregationOperationContext}.
+	 * 
+	 * @return the DBObject
+	 */
+	DBObject toDBObject(AggregationOperationContext context);
+}

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

@@ -0,0 +1,55 @@
+/*
+ * 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.
+ * 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 com.mongodb.DBObject;
+
+/**
+ * The context for an {@link AggregationOperation}.
+ * 
+ * @author Oliver Gierke
+ * @since 1.3
+ */
+public interface AggregationOperationContext {
+
+	/**
+	 * Returns the mapped {@link DBObject}, potentially converting the source considering mapping metadata etc.
+	 * 
+	 * @param dbObject will never be {@literal null}.
+	 * @return must not be {@literal null}.
+	 */
+	DBObject getMappedObject(DBObject dbObject);
+
+	/**
+	 * Returns a {@link FieldReference} for the given field or {@literal null} if the context does not expose the given
+	 * field.
+	 * 
+	 * @param field must not be {@literal null}.
+	 * @return
+	 */
+	FieldReference getReference(Field field);
+
+	/**
+	 * Returns the {@link FieldReference} for the field with the given name or {@literal null} if the context does not
+	 * expose a field with the given name.
+	 * 
+	 * @param name must not be {@literal null} or empty.
+	 * @return
+	 */
+	FieldReference getReference(String name);
+}

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

@@ -0,0 +1,98 @@
+/*
+ * 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.
+ * 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.Iterator;
+import java.util.List;
+
+import org.springframework.util.Assert;
+
+import com.mongodb.DBObject;
+
+/**
+ * Collects the results of executing an aggregation operation.
+ * 
+ * @author Tobias Trelle
+ * @author Oliver Gierke
+ * @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 DBObject rawResults;
+	private final String serverUsed;
+
+	/**
+	 * Creates a new {@link AggregationResults} instance from the given mapped and raw results.
+	 * 
+	 * @param mappedResults must not be {@literal null}.
+	 * @param rawResults must not be {@literal null}.
+	 */
+	public AggregationResults(List<T> mappedResults, DBObject rawResults) {
+
+		Assert.notNull(mappedResults);
+		Assert.notNull(rawResults);
+
+		this.mappedResults = Collections.unmodifiableList(mappedResults);
+		this.rawResults = rawResults;
+		this.serverUsed = parseServerUsed();
+	}
+
+	/**
+	 * Returns the aggregation results.
+	 * 
+	 * @return
+	 */
+	public List<T> getMappedResults() {
+		return mappedResults;
+	}
+
+	/**
+	 * Returns the unique mapped result. Assumes no result or exactly one.
+	 * 
+	 * @return
+	 * @throws IllegalArgumentException in case more than one result is available.
+	 */
+	public T getUniqueMappedResult() {
+		Assert.isTrue(mappedResults.size() < 2, "Expected unique result or null, but got more than one!");
+		return mappedResults.size() == 1 ? mappedResults.get(0) : null;
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see java.lang.Iterable#iterator()
+	 */
+	public Iterator<T> iterator() {
+		return mappedResults.iterator();
+	}
+
+	/**
+	 * Returns the server that has been used to perform the aggregation.
+	 * 
+	 * @return
+	 */
+	public String getServerUsed() {
+		return serverUsed;
+	}
+
+	private String parseServerUsed() {
+
+		Object object = rawResults.get("serverUsed");
+		return object instanceof String ? (String) object : null;
+	}
+}

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

@@ -0,0 +1,402 @@
+/*
+ * 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.
+ * 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.Iterator;
+import java.util.List;
+
+import org.springframework.data.mongodb.core.aggregation.ExposedFields.ExposedField;
+import org.springframework.util.Assert;
+import org.springframework.util.CompositeIterator;
+
+/**
+ * Value object to capture the fields exposed by an {@link AggregationOperation}.
+ * 
+ * @author Oliver Gierke
+ * @author Thomas Darimont
+ * @since 1.3
+ */
+public class ExposedFields implements Iterable<ExposedField> {
+
+	private static final List<ExposedField> NO_FIELDS = Collections.emptyList();
+	private static final ExposedFields EMPTY = new ExposedFields(NO_FIELDS, NO_FIELDS);
+
+	private final List<ExposedField> originalFields;
+	private final List<ExposedField> syntheticFields;
+
+	/**
+	 * Creates a new {@link ExposedFields} instance from the given {@link ExposedField}s.
+	 * 
+	 * @param fields must not be {@literal null}.
+	 * @return
+	 */
+	public static ExposedFields from(ExposedField... fields) {
+		return from(Arrays.asList(fields));
+	}
+
+	/**
+	 * Creates a new {@link ExposedFields} instance from the given {@link ExposedField}s.
+	 * 
+	 * @param fields must not be {@literal null}.
+	 * @return
+	 */
+	private static ExposedFields from(List<ExposedField> fields) {
+
+		ExposedFields result = EMPTY;
+
+		for (ExposedField field : fields) {
+			result = result.and(field);
+		}
+
+		return result;
+	}
+
+	/**
+	 * Creates synthetic {@link ExposedFields} from the given {@link Fields}.
+	 * 
+	 * @param fields must not be {@literal null}.
+	 * @return
+	 */
+	public static ExposedFields synthetic(Fields fields) {
+		return createFields(fields, true);
+	}
+
+	/**
+	 * Creates non-synthetic {@link ExposedFields} from the given {@link Fields}.
+	 * 
+	 * @param fields must not be {@literal null}.
+	 * @return
+	 */
+	public static ExposedFields nonSynthetic(Fields fields) {
+		return createFields(fields, false);
+	}
+
+	/**
+	 * Creates a new {@link ExposedFields} instance for the given fields in either sythetic or non-synthetic way.
+	 * 
+	 * @param fields must not be {@literal null}.
+	 * @param synthetic
+	 * @return
+	 */
+	private static ExposedFields createFields(Fields fields, boolean synthetic) {
+
+		Assert.notNull(fields, "Fields must not be null!");
+		List<ExposedField> result = new ArrayList<ExposedField>();
+
+		for (Field field : fields) {
+			result.add(new ExposedField(field, synthetic));
+		}
+
+		return ExposedFields.from(result);
+	}
+
+	/**
+	 * Creates a new {@link ExposedFields} with the given orignals and synthetics.
+	 * 
+	 * @param originals must not be {@literal null}.
+	 * @param synthetic must not be {@literal null}.
+	 */
+	private ExposedFields(List<ExposedField> originals, List<ExposedField> synthetic) {
+
+		this.originalFields = originals;
+		this.syntheticFields = synthetic;
+	}
+
+	/**
+	 * Creates a new {@link ExposedFields} adding the given {@link ExposedField}.
+	 * 
+	 * @param field must not be {@literal null}.
+	 * @return
+	 */
+	public ExposedFields and(ExposedField field) {
+
+		Assert.notNull(field, "Exposed field must not be null!");
+
+		ArrayList<ExposedField> result = new ArrayList<ExposedField>();
+		result.addAll(field.synthetic ? syntheticFields : originalFields);
+		result.add(field);
+
+		return new ExposedFields(field.synthetic ? originalFields : result, field.synthetic ? result : syntheticFields);
+	}
+
+	/**
+	 * Returns the field with the given name or {@literal null} if no field with the given name is available.
+	 * 
+	 * @param name
+	 * @return
+	 */
+	public ExposedField getField(String name) {
+
+		for (ExposedField field : this) {
+			if (field.canBeReferredToBy(name)) {
+				return field;
+			}
+		}
+
+		return null;
+	}
+
+	/**
+	 * Returns whether the {@link ExposedFields} exposes no non-synthetic fields at all.
+	 * 
+	 * @return
+	 */
+	boolean exposesNoNonSyntheticFields() {
+		return originalFields.isEmpty();
+	}
+
+	/**
+	 * Returns whether the {@link ExposedFields} exposes a single non-synthetic field only.
+	 * 
+	 * @return
+	 */
+	boolean exposesSingleNonSyntheticFieldOnly() {
+		return originalFields.size() == 1;
+	}
+
+	/**
+	 * Returns whether the {@link ExposedFields} exposes no fields at all.
+	 * 
+	 * @return
+	 */
+	boolean exposesNoFields() {
+		return exposedFieldsCount() == 0;
+	}
+
+	/**
+	 * Returns whether the {@link ExposedFields} exposes a single field only.
+	 * 
+	 * @return
+	 */
+	boolean exposesSingleFieldOnly() {
+		return exposedFieldsCount() == 1;
+	}
+
+	/**
+	 * @return
+	 */
+	private int exposedFieldsCount() {
+		return originalFields.size() + syntheticFields.size();
+	}
+
+	/* 
+	 * (non-Javadoc)
+	 * @see java.lang.Iterable#iterator()
+	 */
+	@Override
+	public Iterator<ExposedField> iterator() {
+
+		CompositeIterator<ExposedField> iterator = new CompositeIterator<ExposedField>();
+		iterator.add(syntheticFields.iterator());
+		iterator.add(originalFields.iterator());
+
+		return iterator;
+	}
+
+	/**
+	 * A single exposed field.
+	 * 
+	 * @author Oliver Gierke
+	 */
+	static class ExposedField implements Field {
+
+		private final boolean synthetic;
+		private final Field field;
+
+		/**
+		 * Creates a new {@link ExposedField} with the given key.
+		 * 
+		 * @param key must not be {@literal null} or empty.
+		 * @param synthetic whether the exposed field is synthetic.
+		 */
+		public ExposedField(String key, boolean synthetic) {
+			this(Fields.field(key), synthetic);
+		}
+
+		/**
+		 * Creates a new {@link ExposedField} for the given {@link Field}.
+		 * 
+		 * @param delegate must not be {@literal null}.
+		 * @param synthetic whether the exposed field is synthetic.
+		 */
+		public ExposedField(Field delegate, boolean synthetic) {
+
+			this.field = delegate;
+			this.synthetic = synthetic;
+		}
+
+		/* 
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.Field#getKey()
+		 */
+		@Override
+		public String getName() {
+			return field.getName();
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.Field#getTarget()
+		 */
+		@Override
+		public String getTarget() {
+			return field.getTarget();
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.Field#isAliased()
+		 */
+		@Override
+		public boolean isAliased() {
+			return field.isAliased();
+		}
+
+		/**
+		 * Returns whether the field can be referred to using the given name.
+		 * 
+		 * @param input
+		 * @return
+		 */
+		public boolean canBeReferredToBy(String input) {
+			return getTarget().equals(input);
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see java.lang.Object#toString()
+		 */
+		@Override
+		public String toString() {
+			return String.format("AggregationField: %s, synthetic: %s", field, synthetic);
+		}
+
+		/* 
+		 * (non-Javadoc)
+		 * @see java.lang.Object#equals(java.lang.Object)
+		 */
+		@Override
+		public boolean equals(Object obj) {
+
+			if (this == obj) {
+				return true;
+			}
+
+			if (!(obj instanceof ExposedField)) {
+				return false;
+			}
+
+			ExposedField that = (ExposedField) obj;
+
+			return this.field.equals(that.field) && this.synthetic == that.synthetic;
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see java.lang.Object#hashCode()
+		 */
+		@Override
+		public int hashCode() {
+
+			int result = 17;
+
+			result += 31 * field.hashCode();
+			result += 31 * (synthetic ? 0 : 1);
+
+			return result;
+		}
+	}
+
+	/**
+	 * A reference to an {@link ExposedField}.
+	 * 
+	 * @author Oliver Gierke
+	 */
+	static class FieldReference {
+
+		private final ExposedField field;
+
+		/**
+		 * Creates a new {@link FieldReference} for the given {@link ExposedField}.
+		 * 
+		 * @param field must not be {@literal null}.
+		 */
+		public FieldReference(ExposedField field) {
+
+			Assert.notNull(field, "ExposedField must not be null!");
+			this.field = field;
+		}
+
+		/**
+		 * @return
+		 */
+		public boolean isSynthetic() {
+			return field.synthetic;
+		}
+
+		/**
+		 * Returns the raw, unqualified reference, i.e. the field reference without a {@literal $} prefix.
+		 * 
+		 * @return
+		 */
+		public String getRaw() {
+
+			String target = field.getTarget();
+			return field.synthetic ? target : String.format("%s.%s", Fields.UNDERSCORE_ID, target);
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see java.lang.Object#toString()
+		 */
+		@Override
+		public String toString() {
+			return String.format("$%s", getRaw());
+		}
+
+		/* 
+		 * (non-Javadoc)
+		 * @see java.lang.Object#equals(java.lang.Object)
+		 */
+		@Override
+		public boolean equals(Object obj) {
+
+			if (this == obj) {
+				return true;
+			}
+
+			if (!(obj instanceof FieldReference)) {
+				return false;
+			}
+
+			FieldReference that = (FieldReference) obj;
+
+			return this.field.equals(that.field);
+		}
+
+		/* 
+		 * (non-Javadoc)
+		 * @see java.lang.Object#hashCode()
+		 */
+		@Override
+		public int hashCode() {
+			return field.hashCode();
+		}
+	}
+}

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

@@ -0,0 +1,80 @@
+/*
+ * 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.
+ * 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.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}.
+ * 
+ * @author Thomas Darimont
+ * @author Oliver Gierke
+ * @since 1.4
+ */
+class ExposedFieldsAggregationOperationContext implements AggregationOperationContext {
+
+	private final ExposedFields exposedFields;
+
+	/**
+	 * Creates a new {@link ExposedFieldsAggregationOperationContext} from the given {@link ExposedFields}.
+	 * 
+	 * @param exposedFields must not be {@literal null}.
+	 */
+	public ExposedFieldsAggregationOperationContext(ExposedFields exposedFields) {
+
+		Assert.notNull(exposedFields, "ExposedFields must not be null!");
+		this.exposedFields = exposedFields;
+	}
+
+	/* 
+	 * (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 getReference(field.getTarget());
+	}
+
+	/* 
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperationContext#getReference(java.lang.String)
+	 */
+	@Override
+	public FieldReference getReference(String name) {
+
+		ExposedField field = exposedFields.getField(name);
+
+		if (field != null) {
+			return new FieldReference(field);
+		}
+
+		throw new IllegalArgumentException(String.format("Invalid reference '%s'!", name));
+	}
+}

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

@@ -0,0 +1,46 @@
+/*
+ * 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.
+ * 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;
+
+/**
+ * Abstraction for a field.
+ * 
+ * @author Oliver Gierke
+ * @since 1.3
+ */
+public interface Field {
+
+	/**
+	 * Returns the name of the field.
+	 * 
+	 * @return must not be {@literal null}.
+	 */
+	String getName();
+
+	/**
+	 * Returns the target of the field. In case no explicit target is available {@link #getName()} should be returned.
+	 * 
+	 * @return must not be {@literal null}.
+	 */
+	String getTarget();
+
+	/**
+	 * Returns whether the Field is aliased, which means it has a name set different from the target.
+	 * 
+	 * @return
+	 */
+	boolean isAliased();
+}

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

@@ -0,0 +1,293 @@
+/*
+ * 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.
+ * 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.HashMap;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+
+import org.springframework.util.Assert;
+import org.springframework.util.ObjectUtils;
+import org.springframework.util.StringUtils;
+
+/**
+ * Value object to capture a list of {@link Field} instances.
+ * 
+ * @author Oliver Gierke
+ * @since 1.3
+ */
+public class Fields implements Iterable<Field> {
+
+	private static final String AMBIGUOUS_EXCEPTION = "Found two fields both using '%s' as name: %s and %s! Please "
+			+ "customize your field definitions to get to unique field names!";
+
+	public static String UNDERSCORE_ID = "_id";
+	public static String UNDERSCORE_ID_REF = "$_id";
+
+	private final List<Field> fields;
+
+	/**
+	 * Creates a new {@link Fields} instance from the given {@link Fields}.
+	 * 
+	 * @param fields must not be {@literal null} or empty.
+	 * @return
+	 */
+	public static Fields from(Field... fields) {
+
+		Assert.notNull(fields, "Fields must not be null!");
+		return new Fields(Arrays.asList(fields));
+	}
+
+	/**
+	 * Creates a new {@link Fields} instance for {@link Field}s with the given names.
+	 * 
+	 * @param names must not be {@literal null}.
+	 * @return
+	 */
+	public static Fields fields(String... names) {
+
+		Assert.notNull(names, "Field names must not be null!");
+
+		List<Field> fields = new ArrayList<Field>();
+
+		for (String name : names) {
+			fields.add(field(name));
+		}
+
+		return new Fields(fields);
+	}
+
+	/**
+	 * Creates a {@link Field} with the given name.
+	 * 
+	 * @param name must not be {@literal null} or empty.
+	 * @return
+	 */
+	public static Field field(String name) {
+		return new AggregationField(name);
+	}
+
+	public static Field field(String name, String target) {
+		Assert.hasText(target, "Target must not be null or empty!");
+		return new AggregationField(name, target);
+	}
+
+	/**
+	 * Creates a new {@link Fields} instance using the given {@link Field}s.
+	 * 
+	 * @param fields must not be {@literal null}.
+	 */
+	private Fields(List<Field> fields) {
+
+		Assert.notNull(fields, "Fields must not be null!");
+
+		this.fields = verify(fields);
+	}
+
+	private static final List<Field> verify(List<Field> fields) {
+
+		Map<String, Field> reference = new HashMap<String, Field>();
+
+		for (Field field : fields) {
+
+			String name = field.getName();
+			Field found = reference.get(name);
+
+			if (found != null) {
+				throw new IllegalArgumentException(String.format(AMBIGUOUS_EXCEPTION, name, found, field));
+			}
+
+			reference.put(name, field);
+		}
+
+		return fields;
+	}
+
+	private Fields(Fields existing, Field tail) {
+
+		this.fields = new ArrayList<Field>(existing.fields.size() + 1);
+		this.fields.addAll(existing.fields);
+		this.fields.add(tail);
+	}
+
+	/**
+	 * Creates a new {@link Fields} instance with a new {@link Field} of the given name added.
+	 * 
+	 * @param name must not be {@literal null}.
+	 * @return
+	 */
+	public Fields and(String name) {
+		return and(new AggregationField(name));
+	}
+
+	public Fields and(String name, String target) {
+		return and(new AggregationField(name, target));
+	}
+
+	public Fields and(Field field) {
+		return new Fields(this, field);
+	}
+
+	public Fields and(Fields fields) {
+
+		Fields result = this;
+
+		for (Field field : fields) {
+			result = result.and(field);
+		}
+
+		return result;
+	}
+
+	public Field getField(String name) {
+
+		for (Field field : fields) {
+			if (field.getName().equals(name)) {
+				return field;
+			}
+		}
+
+		return null;
+	}
+
+	/* 
+	 * (non-Javadoc)
+	 * @see java.lang.Iterable#iterator()
+	 */
+	@Override
+	public Iterator<Field> iterator() {
+		return fields.iterator();
+	}
+
+	/**
+	 * Value object to encapsulate a field in an aggregation operation.
+	 * 
+	 * @author Oliver Gierke
+	 */
+	static class AggregationField implements Field {
+
+		private final String name;
+		private final String target;
+
+		/**
+		 * Creates an aggregation fieldwith the given name. As no target is set explicitly, the name will be used as target
+		 * as well.
+		 * 
+		 * @param key
+		 */
+		public AggregationField(String key) {
+			this(key, null);
+		}
+
+		public AggregationField(String name, String target) {
+
+			String nameToSet = cleanUp(name);
+			String targetToSet = cleanUp(target);
+
+			Assert.hasText(nameToSet, "AggregationField name must not be null or empty!");
+
+			if (target == null && name.contains(".")) {
+				this.name = nameToSet.substring(nameToSet.indexOf(".") + 1);
+				this.target = nameToSet;
+			} else {
+				this.name = nameToSet;
+				this.target = targetToSet;
+			}
+		}
+
+		private static final String cleanUp(String source) {
+
+			if (source == null) {
+				return source;
+			}
+
+			int dollarIndex = source.lastIndexOf('$');
+			return dollarIndex == -1 ? source : source.substring(dollarIndex + 1);
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.Field#getKey()
+		 */
+		public String getName() {
+			return name;
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.Field#getAlias()
+		 */
+		public String getTarget() {
+			return StringUtils.hasText(this.target) ? this.target : this.name;
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.Field#isAliased()
+		 */
+		@Override
+		public boolean isAliased() {
+			return !getName().equals(getTarget());
+		}
+
+		/* 
+		 * (non-Javadoc)
+		 * @see java.lang.Object#toString()
+		 */
+		@Override
+		public String toString() {
+			return String.format("AggregationField - name: %s, target: %s", name, target);
+		}
+
+		/* 
+		 * (non-Javadoc)
+		 * @see java.lang.Object#equals(java.lang.Object)
+		 */
+		@Override
+		public boolean equals(Object obj) {
+
+			if (this == obj) {
+				return true;
+			}
+
+			if (!(obj instanceof AggregationField)) {
+				return false;
+			}
+
+			AggregationField that = (AggregationField) obj;
+
+			return this.name.equals(that.name) && ObjectUtils.nullSafeEquals(this.target, that.target);
+		}
+
+		/* 
+		 * (non-Javadoc)
+		 * @see java.lang.Object#hashCode()
+		 */
+		@Override
+		public int hashCode() {
+
+			int result = 17;
+
+			result += 31 * name.hashCode();
+			result += 31 * ObjectUtils.nullSafeHashCode(target);
+
+			return result;
+		}
+	}
+}

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

@@ -0,0 +1,32 @@
+/*
+ * 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.
+ * 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;
+
+/**
+ * {@link AggregationOperation} that exposes new {@link ExposedFields} that can be used for later aggregation pipeline
+ * {@code AggregationOperation}s.
+ * 
+ * @author Thomas Darimont
+ */
+public interface FieldsExposingAggregationOperation extends AggregationOperation {
+
+	/**
+	 * Returns the fields exposed by the {@link AggregationOperation}.
+	 * 
+	 * @return will never be {@literal null}.
+	 */
+	ExposedFields getFields();
+}

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

@@ -0,0 +1,46 @@
+/*
+ * 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.
+ * 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.query.NearQuery;
+import org.springframework.util.Assert;
+
+import com.mongodb.BasicDBObject;
+import com.mongodb.DBObject;
+
+/**
+ * @author Thomas Darimont
+ * @since 1.3
+ */
+public class GeoNearOperation implements AggregationOperation {
+
+	private final NearQuery nearQuery;
+
+	public GeoNearOperation(NearQuery nearQuery) {
+
+		Assert.notNull(nearQuery);
+		this.nearQuery = nearQuery;
+	}
+
+	/* 
+	 * (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("$geoNear", context.getMappedObject(nearQuery.toDBObject()));
+	}
+}

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

@@ -0,0 +1,375 @@
+/*
+ * 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.
+ * 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 java.util.Locale;
+
+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.
+ * 
+ * @see http://docs.mongodb.org/manual/reference/aggregation/group/#stage._S_group
+ * @author Sebastian Herold
+ * @author Thomas Darimont
+ * @author Oliver Gierke
+ * @since 1.3
+ */
+public class GroupOperation implements FieldsExposingAggregationOperation {
+
+	/**
+	 * Holds the non-synthetic fields which are the fields of the group-id structure.
+	 */
+	private final ExposedFields idFields;
+
+	private final List<Operation> operations;
+
+	/**
+	 * Creates a new {@link GroupOperation} including the given {@link Fields}.
+	 * 
+	 * @param fields must not be {@literal null}.
+	 */
+	public GroupOperation(Fields fields) {
+
+		this.idFields = ExposedFields.nonSynthetic(fields);
+		this.operations = new ArrayList<Operation>();
+	}
+
+	/**
+	 * Creates a new {@link GroupOperation} from the given {@link GroupOperation}.
+	 * 
+	 * @param groupOperation must not be {@literal null}.
+	 */
+	protected GroupOperation(GroupOperation groupOperation) {
+		this(groupOperation, Collections.<Operation> emptyList());
+	}
+
+	/**
+	 * Creates a new {@link GroupOperation} from the given {@link GroupOperation} and the given {@link Operation}s.
+	 * 
+	 * @param groupOperation
+	 * @param nextOperations
+	 */
+	private GroupOperation(GroupOperation groupOperation, List<Operation> nextOperations) {
+
+		Assert.notNull(groupOperation, "GroupOperation must not be null!");
+		Assert.notNull(nextOperations, "NextOperations must not be null!");
+
+		this.idFields = groupOperation.idFields;
+		this.operations = new ArrayList<Operation>(nextOperations.size() + 1);
+		this.operations.addAll(groupOperation.operations);
+		this.operations.addAll(nextOperations);
+	}
+
+	/**
+	 * Creates a new {@link GroupOperation} from the current one adding the given {@link Operation}.
+	 * 
+	 * @param operation must not be {@literal null}.
+	 * @return
+	 */
+	protected GroupOperation and(Operation operation) {
+		return new GroupOperation(this, Arrays.asList(operation));
+	}
+
+	/**
+	 * Builder for {@link GroupOperation}s on a field.
+	 * 
+	 * @author Thomas Darimont
+	 */
+	public class GroupOperationBuilder {
+
+		private final GroupOperation groupOperation;
+		private final Operation operation;
+
+		/**
+		 * Creates a new {@link GroupOperationBuilder} from the given {@link GroupOperation} and {@link Operation}.
+		 * 
+		 * @param groupOperation
+		 * @param operation
+		 */
+		private GroupOperationBuilder(GroupOperation groupOperation, Operation operation) {
+
+			Assert.notNull(groupOperation, "GroupOperation must not be null!");
+			Assert.notNull(operation, "Operation must not be null!");
+
+			this.groupOperation = groupOperation;
+			this.operation = operation;
+		}
+
+		/**
+		 * Allows to specify an alias for the new-operation operation.
+		 * 
+		 * @param alias
+		 * @return
+		 */
+		public GroupOperation as(String alias) {
+			return this.groupOperation.and(operation.withAlias(alias));
+		}
+	}
+
+	/**
+	 * Generates an {@link GroupOperationBuilder} for a {@code $sum}-expression.
+	 * <p>
+	 * Count expressions are emulated via {@code $sum: 1}.
+	 * <p>
+	 * 
+	 * @return
+	 */
+	public GroupOperationBuilder count() {
+		return newBuilder(GroupOps.SUM, null, 1);
+	}
+
+	/**
+	 * Generates an {@link GroupOperationBuilder} for a {@code $sum}-expression for the given field-reference.
+	 * 
+	 * @param reference
+	 * @return
+	 */
+	public GroupOperationBuilder sum(String reference) {
+		return sum(reference, null);
+	}
+
+	private GroupOperationBuilder sum(String reference, Object value) {
+		return newBuilder(GroupOps.SUM, reference, value);
+	}
+
+	/**
+	 * Generates an {@link GroupOperationBuilder} for an {@code $add_to_set}-expression for the given field-reference.
+	 * 
+	 * @param reference
+	 * @return
+	 */
+	public GroupOperationBuilder addToSet(String reference) {
+		return addToSet(reference, null);
+	}
+
+	/**
+	 * Generates an {@link GroupOperationBuilder} for an {@code $add_to_set}-expression for the given value.
+	 * 
+	 * @param value
+	 * @return
+	 */
+	public GroupOperationBuilder addToSet(Object value) {
+		return addToSet(null, value);
+	}
+
+	private GroupOperationBuilder addToSet(String reference, Object value) {
+		return newBuilder(GroupOps.ADD_TO_SET, reference, value);
+	}
+
+	/**
+	 * Generates an {@link GroupOperationBuilder} for an {@code $last}-expression for the given field-reference.
+	 * 
+	 * @param reference
+	 * @return
+	 */
+	public GroupOperationBuilder last(String reference) {
+		return newBuilder(GroupOps.LAST, reference, null);
+	}
+
+	/**
+	 * Generates an {@link GroupOperationBuilder} for a {@code $first}-expression for the given field-reference.
+	 * 
+	 * @param reference
+	 * @return
+	 */
+	public GroupOperationBuilder first(String reference) {
+		return newBuilder(GroupOps.FIRST, reference, null);
+	}
+
+	/**
+	 * Generates an {@link GroupOperationBuilder} for an {@code $avg}-expression for the given field-reference.
+	 * 
+	 * @param reference
+	 * @return
+	 */
+	public GroupOperationBuilder avg(String reference) {
+		return newBuilder(GroupOps.AVG, reference, null);
+	}
+
+	/**
+	 * Generates an {@link GroupOperationBuilder} for an {@code $push}-expression for the given field-reference.
+	 * 
+	 * @param reference
+	 * @return
+	 */
+	public GroupOperationBuilder push(String reference) {
+		return push(reference, null);
+	}
+
+	/**
+	 * Generates an {@link GroupOperationBuilder} for an {@code $push}-expression for the given value.
+	 * 
+	 * @param value
+	 * @return
+	 */
+	public GroupOperationBuilder push(Object value) {
+		return push(null, value);
+	}
+
+	private GroupOperationBuilder push(String reference, Object value) {
+		return newBuilder(GroupOps.PUSH, reference, value);
+	}
+
+	/**
+	 * Generates an {@link GroupOperationBuilder} for an {@code $min}-expression that for the given field-reference.
+	 * 
+	 * @param reference
+	 * @return
+	 */
+	public GroupOperationBuilder min(String reference) {
+		return newBuilder(GroupOps.MIN, reference, null);
+	}
+
+	/**
+	 * Generates an {@link GroupOperationBuilder} for an {@code $max}-expression that for the given field-reference.
+	 * 
+	 * @param reference
+	 * @return
+	 */
+	public GroupOperationBuilder max(String reference) {
+		return newBuilder(GroupOps.MAX, reference, null);
+	}
+
+	private GroupOperationBuilder newBuilder(Keyword keyword, String reference, Object value) {
+		return new GroupOperationBuilder(this, new Operation(keyword, null, reference, value));
+	}
+
+	/* 
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperationContext#getFields()
+	 */
+	@Override
+	public ExposedFields getFields() {
+
+		ExposedFields fields = this.idFields.and(new ExposedField(Fields.UNDERSCORE_ID, true));
+
+		for (Operation operation : operations) {
+			fields = fields.and(operation.asField());
+		}
+
+		return fields;
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperation#toDBObject(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
+	 */
+	@Override
+	public com.mongodb.DBObject toDBObject(AggregationOperationContext context) {
+
+		BasicDBObject operationObject = new BasicDBObject();
+
+		if (idFields.exposesNoNonSyntheticFields()) {
+
+			operationObject.put(Fields.UNDERSCORE_ID, null);
+
+		} else if (idFields.exposesSingleNonSyntheticFieldOnly()) {
+
+			FieldReference reference = context.getReference(idFields.iterator().next());
+			operationObject.put(Fields.UNDERSCORE_ID, reference.toString());
+
+		} else {
+
+			BasicDBObject inner = new BasicDBObject();
+
+			for (ExposedField field : idFields) {
+				FieldReference reference = context.getReference(field);
+				inner.put(field.getName(), reference.toString());
+			}
+
+			operationObject.put(Fields.UNDERSCORE_ID, inner);
+		}
+
+		for (Operation operation : operations) {
+			operationObject.putAll(operation.toDBObject(context));
+		}
+
+		return new BasicDBObject("$group", operationObject);
+	}
+
+	interface Keyword {
+
+		String toString();
+	}
+
+	private static enum GroupOps implements Keyword {
+
+		SUM, LAST, FIRST, PUSH, AVG, MIN, MAX, ADD_TO_SET, COUNT;
+
+		@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();
+		}
+	}
+
+	static class Operation implements AggregationOperation {
+
+		private final Keyword op;
+		private final String key;
+		private final String reference;
+		private final Object value;
+
+		public Operation(Keyword op, String key, String reference, Object value) {
+
+			this.op = op;
+			this.key = key;
+			this.reference = reference;
+			this.value = value;
+		}
+
+		public Operation withAlias(String key) {
+			return new Operation(op, key, reference, value);
+		}
+
+		public ExposedField asField() {
+			return new ExposedField(key, true);
+		}
+
+		public DBObject toDBObject(AggregationOperationContext context) {
+			return new BasicDBObject(key, new BasicDBObject(op.toString(), getValue(context)));
+		}
+
+		public Object getValue(AggregationOperationContext context) {
+			return reference == null ? value : context.getReference(reference).toString();
+		}
+
+		@Override
+		public String toString() {
+			return "Operation [op=" + op + ", key=" + key + ", reference=" + reference + ", value=" + value + "]";
+		}
+	}
+}

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

@@ -0,0 +1,52 @@
+/*
+ * 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.
+ * 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.BasicDBObject;
+import com.mongodb.DBObject;
+
+/**
+ * Encapsulates the {@code $limit}-operation
+ * 
+ * @see http://docs.mongodb.org/manual/reference/aggregation/limit/
+ * @author Thomas Darimont
+ * @author Oliver Gierke
+ * @since 1.3
+ */
+class LimitOperation implements AggregationOperation {
+
+	private final long maxElements;
+
+	/**
+	 * @param maxElements Number of documents to consider.
+	 */
+	public LimitOperation(long maxElements) {
+
+		Assert.isTrue(maxElements >= 0, "Maximum number of elements must be greater or equal to zero!");
+		this.maxElements = maxElements;
+	}
+
+	/* 
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperation#toDBObject(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
+	 */
+	@Override
+	public DBObject toDBObject(AggregationOperationContext context) {
+		return new BasicDBObject("$limit", maxElements);
+	}
+}

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

@@ -0,0 +1,56 @@
+/*
+ * 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.
+ * 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.query.Criteria;
+import org.springframework.util.Assert;
+
+import com.mongodb.BasicDBObject;
+import com.mongodb.DBObject;
+
+/**
+ * Encapsulates the {@code $match}-operation
+ * 
+ * @see http://docs.mongodb.org/manual/reference/aggregation/match/
+ * @author Sebastian Herold
+ * @author Thomas Darimont
+ * @author Oliver Gierke
+ * @since 1.3
+ */
+public class MatchOperation implements AggregationOperation {
+
+	private final Criteria criteria;
+
+	/**
+	 * Creates a new {@link MatchOperation} for the given {@link Criteria}.
+	 * 
+	 * @param criteria must not be {@literal null}.
+	 */
+	public MatchOperation(Criteria criteria) {
+
+		Assert.notNull(criteria, "Criteria must not be null!");
+		this.criteria = criteria;
+	}
+
+	/* 
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperation#toDBObject(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
+	 */
+	@Override
+	public DBObject toDBObject(AggregationOperationContext context) {
+		return new BasicDBObject("$match", context.getMappedObject(criteria.getCriteriaObject()));
+	}
+}

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

@@ -0,0 +1,774 @@
+/*
+ * 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.
+ * 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.ExposedFields.ExposedField;
+import org.springframework.data.mongodb.core.aggregation.ExposedFields.FieldReference;
+import org.springframework.data.mongodb.core.aggregation.ProjectionOperation.ProjectionOperationBuilder.FieldProjection;
+import org.springframework.util.Assert;
+
+import com.mongodb.BasicDBList;
+import com.mongodb.BasicDBObject;
+import com.mongodb.DBObject;
+
+/**
+ * Encapsulates the aggregation framework {@code $project}-operation. Projection of field to be used in an
+ * {@link Aggregation}. A projection is similar to a {@link Field} inclusion/exclusion but more powerful. It can
+ * generate new fields, change values of given field etc.
+ * <p>
+ * 
+ * @see http://docs.mongodb.org/manual/reference/aggregation/project/
+ * @author Tobias Trelle
+ * @author Thomas Darimont
+ * @author Oliver Gierke
+ * @since 1.3
+ */
+public class ProjectionOperation implements FieldsExposingAggregationOperation {
+
+	private static final List<Projection> NONE = Collections.emptyList();
+	private static final String EXCLUSION_ERROR = "Exclusion of field %s not allowed. Projections by the mongodb "
+			+ "aggregation framework only support the exclusion of the %s field!";
+
+	private final List<Projection> projections;
+
+	/**
+	 * Creates a new empty {@link ProjectionOperation}.
+	 */
+	public ProjectionOperation() {
+		this(NONE, NONE);
+	}
+
+	/**
+	 * Creates a new {@link ProjectionOperation} including the given {@link Fields}.
+	 * 
+	 * @param fields must not be {@literal null}.
+	 */
+	public ProjectionOperation(Fields fields) {
+		this(NONE, ProjectionOperationBuilder.FieldProjection.from(fields));
+	}
+
+	/**
+	 * Copy constructor to allow building up {@link ProjectionOperation} instances from already existing
+	 * {@link Projection}s.
+	 * 
+	 * @param current must not be {@literal null}.
+	 * @param projections must not be {@literal null}.
+	 */
+	private ProjectionOperation(List<? extends Projection> current, List<? extends Projection> projections) {
+
+		Assert.notNull(current, "Current projections must not be null!");
+		Assert.notNull(projections, "Projections must not be null!");
+
+		this.projections = new ArrayList<ProjectionOperation.Projection>(current.size() + projections.size());
+		this.projections.addAll(current);
+		this.projections.addAll(projections);
+	}
+
+	/**
+	 * Creates a new {@link ProjectionOperation} with the current {@link Projection}s and the given one.
+	 * 
+	 * @param projection must not be {@literal null}.
+	 * @return
+	 */
+	private ProjectionOperation and(Projection projection) {
+		return new ProjectionOperation(this.projections, Arrays.asList(projection));
+	}
+
+	/**
+	 * Creates a new {@link ProjectionOperation} with the current {@link Projection}s replacing the last current one with
+	 * the given one.
+	 * 
+	 * @param projection must not be {@literal null}.
+	 * @return
+	 */
+	private ProjectionOperation andReplaceLastOneWith(Projection projection) {
+
+		List<Projection> projections = this.projections.isEmpty() ? Collections.<Projection> emptyList() : this.projections
+				.subList(0, this.projections.size() - 1);
+		return new ProjectionOperation(projections, Arrays.asList(projection));
+	}
+
+	/**
+	 * Creates a new {@link ProjectionOperationBuilder} to define a projection for the field with the given name.
+	 * 
+	 * @param name must not be {@literal null} or empty.
+	 * @return
+	 */
+	public ProjectionOperationBuilder and(String name) {
+		return new ProjectionOperationBuilder(name, this, null);
+	}
+
+	public ExpressionProjectionOperationBuilder andExpression(String expression, Object... params) {
+		return new ExpressionProjectionOperationBuilder(expression, this, params);
+	}
+
+	/**
+	 * Excludes the given fields from the projection.
+	 * 
+	 * @param fieldNames must not be {@literal null}.
+	 * @return
+	 */
+	public ProjectionOperation andExclude(String... fieldNames) {
+
+		for (String fieldName : fieldNames) {
+			Assert.isTrue(Fields.UNDERSCORE_ID.equals(fieldName),
+					String.format(EXCLUSION_ERROR, fieldName, Fields.UNDERSCORE_ID));
+		}
+
+		List<FieldProjection> excludeProjections = FieldProjection.from(Fields.fields(fieldNames), false);
+		return new ProjectionOperation(this.projections, excludeProjections);
+	}
+
+	/**
+	 * Includes the given fields into the projection.
+	 * 
+	 * @param fieldNames must not be {@literal null}.
+	 * @return
+	 */
+	public ProjectionOperation andInclude(String... fieldNames) {
+
+		List<FieldProjection> projections = FieldProjection.from(Fields.fields(fieldNames), true);
+		return new ProjectionOperation(this.projections, projections);
+	}
+
+	/**
+	 * Includes the given fields into the projection.
+	 * 
+	 * @param fields must not be {@literal null}.
+	 * @return
+	 */
+	public ProjectionOperation andInclude(Fields fields) {
+		return new ProjectionOperation(this.projections, FieldProjection.from(fields, true));
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.FieldsExposingAggregationOperation#getFields()
+	 */
+	@Override
+	public ExposedFields getFields() {
+
+		ExposedFields fields = null;
+
+		for (Projection projection : projections) {
+			ExposedField field = projection.getExposedField();
+			fields = fields == null ? ExposedFields.from(field) : fields.and(field);
+		}
+
+		return fields;
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperation#toDBObject(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
+	 */
+	@Override
+	public DBObject toDBObject(AggregationOperationContext context) {
+
+		BasicDBObject fieldObject = new BasicDBObject();
+
+		for (Projection projection : projections) {
+			fieldObject.putAll(projection.toDBObject(context));
+		}
+
+		return new BasicDBObject("$project", fieldObject);
+	}
+
+	/**
+	 * Base class for {@link ProjectionOperationBuilder}s.
+	 * 
+	 * @author Thomas Darimont
+	 */
+	private static abstract class AbstractProjectionOperationBuilder implements AggregationOperation {
+
+		protected final Object value;
+		protected final ProjectionOperation operation;
+
+		/**
+		 * Creates a new {@link AbstractProjectionOperationBuilder} fot the given value and {@link ProjectionOperation}.
+		 * 
+		 * @param value must not be {@literal null}.
+		 * @param operation must not be {@literal null}.
+		 */
+		public AbstractProjectionOperationBuilder(Object value, ProjectionOperation 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;
+		}
+
+		/* 
+		 * (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 this.operation.toDBObject(context);
+		}
+
+		/**
+		 * Returns the finally to be applied {@link ProjectionOperation} with the given alias.
+		 * 
+		 * @param alias will never be {@literal null} or empty.
+		 * @return
+		 */
+		public abstract ProjectionOperation as(String alias);
+	}
+
+	/**
+	 * @author Thomas Darimont
+	 */
+	public static class ExpressionProjectionOperationBuilder extends AbstractProjectionOperationBuilder {
+
+		private final Object[] params;
+
+		/**
+		 * Creates a new {@link ExpressionProjectionOperationBuilder} for the given value, {@link ProjectionOperation} and
+		 * parameters.
+		 * 
+		 * @param value must not be {@literal null}.
+		 * @param operation must not be {@literal null}.
+		 * @param parameters
+		 */
+		public ExpressionProjectionOperationBuilder(Object value, ProjectionOperation operation, Object[] parameters) {
+
+			super(value, operation);
+			this.params = parameters;
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.ProjectionOperation.AbstractProjectionOperationBuilder#as(java.lang.String)
+		 */
+		@Override
+		public ProjectionOperation as(String alias) {
+
+			Field expressionField = Fields.field(alias, "expr");
+			return this.operation.and(new ExpressionProjection(expressionField, this.value.toString(), params));
+		}
+
+		/**
+		 * A {@link Projection} based on a SpEL expression.
+		 * 
+		 * @author Thomas Darimont
+		 * @author Oliver Gierke
+		 */
+		static class ExpressionProjection extends Projection {
+
+			private static final SpelExpressionTransformer TRANSFORMER = new SpelExpressionTransformer();
+
+			private final String expression;
+			private final Object[] params;
+
+			/**
+			 * Creates a new {@link ExpressionProjection} for the given field, SpEL expression and parameters.
+			 * 
+			 * @param field must not be {@literal null}.
+			 * @param expression must not be {@literal null} or empty.
+			 * @param parameters must not be {@literal null}.
+			 */
+			public ExpressionProjection(Field field, String expression, Object[] parameters) {
+
+				super(field);
+
+				Assert.hasText(expression, "Expression must not be null!");
+				Assert.notNull(parameters, "Parameters must not be null!");
+
+				this.expression = expression;
+				this.params = parameters;
+			}
+
+			/* 
+			 * (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) {
+				return new BasicDBObject(getExposedField().getName(), TRANSFORMER.transform(expression, context, params));
+			}
+		}
+	}
+
+	/**
+	 * Builder for {@link ProjectionOperation}s on a field.
+	 * 
+	 * @author Oliver Gierke
+	 * @author Thomas Darimont
+	 */
+	public static class ProjectionOperationBuilder extends AbstractProjectionOperationBuilder {
+
+		private final String name;
+		private final ProjectionOperation operation;
+		private final OperationProjection previousProjection;
+
+		/**
+		 * Creates a new {@link ProjectionOperationBuilder} for the field with the given name on top of the given
+		 * {@link ProjectionOperation}.
+		 * 
+		 * @param name must not be {@literal null} or empty.
+		 * @param operation must not be {@literal null}.
+		 * @param previousProjection the previous operation projection, may be {@literal null}.
+		 */
+		public ProjectionOperationBuilder(String name, ProjectionOperation operation, OperationProjection previousProjection) {
+			super(name, operation);
+
+			this.name = name;
+			this.operation = operation;
+			this.previousProjection = previousProjection;
+		}
+
+		/**
+		 * Projects the result of the previous operation onto the current field. Will automatically add an exclusion for
+		 * {@code _id} as what would be held in it by default will now go into the field just projected into.
+		 * 
+		 * @return
+		 */
+		public ProjectionOperation previousOperation() {
+
+			return this.operation.andExclude(Fields.UNDERSCORE_ID) //
+					.and(new PreviousOperationProjection(name));
+		}
+
+		/**
+		 * Defines a nested field binding for the current field.
+		 * 
+		 * @param fields must not be {@literal null}.
+		 * @return
+		 */
+		public ProjectionOperation nested(Fields fields) {
+			return this.operation.and(new NestedFieldProjection(name, fields));
+		}
+
+		/**
+		 * Allows to specify an alias for the previous projection operation.
+		 * 
+		 * @param string
+		 * @return
+		 */
+		@Override
+		public ProjectionOperation as(String alias) {
+
+			if (this.previousProjection != null) {
+				return this.operation.andReplaceLastOneWith(this.previousProjection.withAlias(alias));
+			} else {
+				return this.operation.and(new FieldProjection(Fields.field(alias, name), null));
+			}
+		}
+
+		/**
+		 * Generates an {@code $add} expression that adds the given number to the previously mentioned field.
+		 * 
+		 * @param number
+		 * @return
+		 */
+		public ProjectionOperationBuilder plus(Number number) {
+
+			Assert.notNull(number, "Number must not be null!");
+			return project("add", number);
+		}
+
+		/**
+		 * Generates an {@code $add} expression that adds the value of the given field to the previously mentioned field.
+		 * 
+		 * @param fieldReference
+		 * @return
+		 */
+		public ProjectionOperationBuilder plus(String fieldReference) {
+
+			Assert.notNull(fieldReference, "Field reference must not be null!");
+			return project("add", Fields.field(fieldReference));
+		}
+
+		/**
+		 * Generates an {@code $subtract} expression that subtracts the given number to the previously mentioned field.
+		 * 
+		 * @param number
+		 * @return
+		 */
+		public ProjectionOperationBuilder minus(Number number) {
+
+			Assert.notNull(number, "Number must not be null!");
+			return project("subtract", number);
+		}
+
+		/**
+		 * Generates an {@code $subtract} expression that subtracts the value of the given field to the previously mentioned
+		 * field.
+		 * 
+		 * @param fieldReference
+		 * @return
+		 */
+		public ProjectionOperationBuilder minus(String fieldReference) {
+
+			Assert.notNull(fieldReference, "Field reference must not be null!");
+			return project("subtract", Fields.field(fieldReference));
+		}
+
+		/**
+		 * Generates an {@code $multiply} expression that multiplies the given number with the previously mentioned field.
+		 * 
+		 * @param number
+		 * @return
+		 */
+		public ProjectionOperationBuilder multiply(Number number) {
+
+			Assert.notNull(number, "Number must not be null!");
+			return project("multiply", number);
+		}
+
+		/**
+		 * Generates an {@code $multiply} expression that multiplies the value of the given field with the previously
+		 * mentioned field.
+		 * 
+		 * @param fieldReference
+		 * @return
+		 */
+		public ProjectionOperationBuilder multiply(String fieldReference) {
+
+			Assert.notNull(fieldReference, "Field reference must not be null!");
+			return project("multiply", Fields.field(fieldReference));
+		}
+
+		/**
+		 * Generates an {@code $divide} expression that divides the previously mentioned field by the given number.
+		 * 
+		 * @param number
+		 * @return
+		 */
+		public ProjectionOperationBuilder divide(Number number) {
+
+			Assert.notNull(number, "Number must not be null!");
+			Assert.isTrue(Math.abs(number.intValue()) != 0, "Number must not be zero!");
+			return project("divide", number);
+		}
+
+		/**
+		 * Generates an {@code $divide} expression that divides the value of the given field by the previously mentioned
+		 * field.
+		 * 
+		 * @param fieldReference
+		 * @return
+		 */
+		public ProjectionOperationBuilder divide(String fieldReference) {
+
+			Assert.notNull(fieldReference, "Field reference must not be null!");
+			return project("divide", Fields.field(fieldReference));
+		}
+
+		/**
+		 * Generates an {@code $mod} expression that divides the previously mentioned field by the given number and returns
+		 * the remainder.
+		 * 
+		 * @param number
+		 * @return
+		 */
+		public ProjectionOperationBuilder mod(Number number) {
+
+			Assert.notNull(number, "Number must not be null!");
+			Assert.isTrue(Math.abs(number.intValue()) != 0, "Number must not be zero!");
+			return project("mod", number);
+		}
+
+		/**
+		 * 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
+		 */
+		public ProjectionOperationBuilder mod(String fieldReference) {
+
+			Assert.notNull(fieldReference, "Field reference must not be null!");
+			return project("mod", Fields.field(fieldReference));
+		}
+
+		/* 
+		 * (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 this.operation.toDBObject(context);
+		}
+
+		/**
+		 * Adds a generic projection for the current field.
+		 * 
+		 * @param operation the operation key, e.g. {@code $add}.
+		 * @param values the values to be set for the projection operation.
+		 * @return
+		 */
+		public ProjectionOperationBuilder project(String operation, Object... values) {
+			OperationProjection projectionOperation = new OperationProjection(Fields.field(name), operation, values);
+			return new ProjectionOperationBuilder(name, this.operation.and(projectionOperation), projectionOperation);
+		}
+
+		/**
+		 * A {@link Projection} to pull in the result of the previous operation.
+		 * 
+		 * @author Oliver Gierke
+		 */
+		static class PreviousOperationProjection extends Projection {
+
+			private final String name;
+
+			/**
+			 * Creates a new {@link PreviousOperationProjection} for the field with the given name.
+			 * 
+			 * @param name must not be {@literal null} or empty.
+			 */
+			public PreviousOperationProjection(String name) {
+				super(Fields.field(name));
+				this.name = name;
+			}
+
+			/* 
+			 * (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) {
+				return new BasicDBObject(name, Fields.UNDERSCORE_ID_REF);
+			}
+		}
+
+		/**
+		 * A {@link FieldProjection} to map a result of a previous {@link AggregationOperation} to a new field.
+		 * 
+		 * @author Oliver Gierke
+		 * @author Thomas Darimont
+		 */
+		static class FieldProjection extends Projection {
+
+			private final Field field;
+			private final Object value;
+
+			/**
+			 * Creates a new {@link FieldProjection} for the field of the given name, assigning the given value.
+			 * 
+			 * @param name must not be {@literal null} or empty.
+			 * @param value
+			 */
+			public FieldProjection(String name, Object value) {
+				this(Fields.field(name), value);
+			}
+
+			private FieldProjection(Field field, Object value) {
+
+				super(field);
+
+				this.field = field;
+				this.value = value;
+			}
+
+			/**
+			 * Factory method to easily create {@link FieldProjection}s for the given {@link Fields}. Fields are projected as
+			 * references with their given name. A field {@code foo} will be projected as: {@code foo : 1 } .
+			 * 
+			 * @param fields the {@link Fields} to in- or exclude, must not be {@literal null}.
+			 * @return
+			 */
+			public static List<? extends Projection> from(Fields fields) {
+				return from(fields, null);
+			}
+
+			/**
+			 * Factory method to easily create {@link FieldProjection}s for the given {@link Fields}.
+			 * 
+			 * @param fields the {@link Fields} to in- or exclude, must not be {@literal null}.
+			 * @param value to use for the given field.
+			 * @return
+			 */
+			public static List<FieldProjection> from(Fields fields, Object value) {
+
+				Assert.notNull(fields, "Fields must not be null!");
+				List<FieldProjection> projections = new ArrayList<FieldProjection>();
+
+				for (Field field : fields) {
+					projections.add(new FieldProjection(field, value));
+				}
+
+				return projections;
+			}
+
+			/* 
+			 * (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) {
+				return new BasicDBObject(field.getName(), renderFieldValue(context));
+			}
+
+			private Object renderFieldValue(AggregationOperationContext context) {
+
+				// implicit reference or explicit include?
+				if (value == null || Boolean.TRUE.equals(value)) {
+
+					// check whether referenced field exists in the context
+					FieldReference reference = context.getReference(field.getTarget());
+					return reference.isSynthetic() && !field.isAliased() ? 1 : reference.toString();
+
+				} else if (Boolean.FALSE.equals(value)) {
+
+					// render field as excluded
+					return 0;
+				}
+
+				return value;
+			}
+		}
+
+		static class OperationProjection extends Projection {
+
+			private final Field field;
+			private final String operation;
+			private final List<Object> values;
+
+			/**
+			 * Creates a new {@link OperationProjection} for the given field.
+			 * 
+			 * @param name the name of the field to add the operation projection for, must not be {@literal null} or empty.
+			 * @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 OperationProjection(Field field, String operation, Object[] values) {
+
+				super(field);
+
+				Assert.hasText(operation, "Operation must not be null or empty!");
+				Assert.notNull(values, "Values must not be null!");
+
+				this.field = field;
+				this.operation = operation;
+				this.values = Arrays.asList(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) {
+
+				BasicDBList values = new BasicDBList();
+				values.addAll(buildReferences(context));
+
+				DBObject inner = new BasicDBObject("$" + operation, values);
+
+				return new BasicDBObject(this.field.getName(), inner);
+			}
+
+			private List<Object> buildReferences(AggregationOperationContext context) {
+
+				List<Object> result = new ArrayList<Object>(values.size());
+				result.add(context.getReference(field.getTarget()).toString());
+
+				for (Object element : values) {
+					result.add(element instanceof Field ? context.getReference((Field) element).toString() : element);
+				}
+
+				return result;
+			}
+
+			/**
+			 * Creates a new instance of this {@link OperationProjection} with the given alias.
+			 * 
+			 * @param alias the alias to set
+			 * @return
+			 */
+			public OperationProjection withAlias(String alias) {
+				return new OperationProjection(Fields.field(alias, this.field.getName()), operation, values.toArray());
+			}
+		}
+
+		static class NestedFieldProjection extends Projection {
+
+			private final String name;
+			private final Fields fields;
+
+			public NestedFieldProjection(String name, Fields fields) {
+
+				super(Fields.field(name));
+				this.name = name;
+				this.fields = fields;
+			}
+
+			/* 
+			 * (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) {
+
+				DBObject nestedObject = new BasicDBObject();
+
+				for (Field field : fields) {
+					nestedObject.put(field.getName(), context.getReference(field.getTarget()).toString());
+				}
+
+				return new BasicDBObject(name, nestedObject);
+			}
+		}
+	}
+
+	/**
+	 * Base class for {@link Projection} implementations.
+	 * 
+	 * @author Oliver Gierke
+	 */
+	private static abstract class Projection {
+
+		private final ExposedField field;
+
+		/**
+		 * Creates new {@link Projection} for the given {@link Field}.
+		 * 
+		 * @param field must not be {@literal null}.
+		 */
+		public Projection(Field field) {
+
+			Assert.notNull(field, "Field must not be null!");
+			this.field = new ExposedField(field, true);
+		}
+
+		/**
+		 * Returns the field exposed by the {@link Projection}.
+		 * 
+		 * @return will never be {@literal null}.
+		 */
+		public ExposedField getExposedField() {
+			return field;
+		}
+
+		/**
+		 * 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 DBObject toDBObject(AggregationOperationContext context);
+	}
+
+}

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

@@ -0,0 +1,54 @@
+/*
+ * 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.
+ * 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.BasicDBObject;
+import com.mongodb.DBObject;
+
+/**
+ * Encapsulates the aggregation framework {@code $skip}-operation.
+ * 
+ * @see http://docs.mongodb.org/manual/reference/aggregation/skip/
+ * @author Thomas Darimont
+ * @author Oliver Gierke
+ * @since 1.3
+ */
+public class SkipOperation implements AggregationOperation {
+
+	private final long skipCount;
+
+	/**
+	 * Creates a new {@link SkipOperation} skipping the given number of elements.
+	 * 
+	 * @param skipCount number of documents to skip.
+	 */
+	public SkipOperation(long skipCount) {
+
+		Assert.isTrue(skipCount >= 0, "Skip count must not be negative!");
+		this.skipCount = skipCount;
+	}
+
+	/* 
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperation#toDBObject(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
+	 */
+	@Override
+	public DBObject toDBObject(AggregationOperationContext context) {
+		return new BasicDBObject("$skip", skipCount);
+	}
+}

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

@@ -0,0 +1,76 @@
+/*
+ * 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.
+ * 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.domain.Sort;
+import org.springframework.data.domain.Sort.Direction;
+import org.springframework.data.domain.Sort.Order;
+import org.springframework.data.mongodb.core.aggregation.ExposedFields.FieldReference;
+import org.springframework.util.Assert;
+
+import com.mongodb.BasicDBObject;
+import com.mongodb.DBObject;
+
+/**
+ * Encapsulates the aggregation framework {@code $sort}-operation.
+ * 
+ * @see http://docs.mongodb.org/manual/reference/aggregation/sort/#pipe._S_sort
+ * @author Thomas Darimont
+ * @author Oliver Gierke
+ * @since 1.3
+ */
+public class SortOperation implements AggregationOperation {
+
+	private final Sort sort;
+
+	/**
+	 * Creates a new {@link SortOperation} for the given {@link Sort} instance.
+	 * 
+	 * @param sort must not be {@literal null}.
+	 */
+	public SortOperation(Sort sort) {
+
+		Assert.notNull(sort, "Sort must not be null!");
+		this.sort = sort;
+	}
+
+	public SortOperation and(Direction direction, String... fields) {
+		return and(new Sort(direction, fields));
+	}
+
+	public SortOperation and(Sort sort) {
+		return new SortOperation(this.sort.and(sort));
+	}
+
+	/* 
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperation#toDBObject(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
+	 */
+	@Override
+	public DBObject toDBObject(AggregationOperationContext context) {
+
+		BasicDBObject object = new BasicDBObject();
+
+		for (Order order : sort) {
+
+			// Check reference
+			FieldReference reference = context.getReference(order.getProperty());
+			object.put(reference.getRaw(), order.isAscending() ? 1 : -1);
+		}
+
+		return new BasicDBObject("$sort", object);
+	}
+}

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

@@ -0,0 +1,513 @@
+/*
+ * 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.
+ * 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 static org.springframework.data.mongodb.util.DBObjectUtils.*;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+import org.springframework.core.GenericTypeResolver;
+import org.springframework.data.mongodb.core.spel.ExpressionNode;
+import org.springframework.data.mongodb.core.spel.ExpressionTransformationContextSupport;
+import org.springframework.data.mongodb.core.spel.LiteralNode;
+import org.springframework.data.mongodb.core.spel.MethodReferenceNode;
+import org.springframework.data.mongodb.core.spel.OperatorNode;
+import org.springframework.expression.spel.ExpressionState;
+import org.springframework.expression.spel.SpelNode;
+import org.springframework.expression.spel.SpelParserConfiguration;
+import org.springframework.expression.spel.ast.CompoundExpression;
+import org.springframework.expression.spel.ast.Indexer;
+import org.springframework.expression.spel.ast.InlineList;
+import org.springframework.expression.spel.ast.PropertyOrFieldReference;
+import org.springframework.expression.spel.standard.SpelExpression;
+import org.springframework.expression.spel.standard.SpelExpressionParser;
+import org.springframework.expression.spel.support.StandardEvaluationContext;
+import org.springframework.util.Assert;
+import org.springframework.util.NumberUtils;
+
+import com.mongodb.BasicDBList;
+import com.mongodb.BasicDBObject;
+import com.mongodb.DBObject;
+
+/**
+ * Renders the AST of a SpEL expression as a MongoDB Aggregation Framework projection expression.
+ * 
+ * @author Thomas Darimont
+ */
+class SpelExpressionTransformer implements AggregationExpressionTransformer {
+
+	// TODO: remove explicit usage of a configuration once SPR-11031 gets fixed
+	private static final SpelParserConfiguration CONFIG = new SpelParserConfiguration(false, false);
+	private static final SpelExpressionParser PARSER = new SpelExpressionParser(CONFIG);
+	private final List<ExpressionNodeConversion<? extends ExpressionNode>> conversions;
+
+	/**
+	 * Creates a new {@link SpelExpressionTransformer}.
+	 */
+	public SpelExpressionTransformer() {
+
+		List<ExpressionNodeConversion<? extends ExpressionNode>> conversions = new ArrayList<ExpressionNodeConversion<? extends ExpressionNode>>();
+		conversions.add(new OperatorNodeConversion(this));
+		conversions.add(new LiteralNodeConversion(this));
+		conversions.add(new IndexerNodeConversion(this));
+		conversions.add(new InlineListNodeConversion(this));
+		conversions.add(new PropertyOrFieldReferenceNodeConversion(this));
+		conversions.add(new CompoundExpressionNodeConversion(this));
+		conversions.add(new MethodReferenceNodeConversion(this));
+
+		this.conversions = Collections.unmodifiableList(conversions);
+	}
+
+	/**
+	 * Transforms the given SpEL expression to a corresponding MongoDB expression against the given
+	 * {@link AggregationOperationContext} {@code context}.
+	 * <p>
+	 * Exposes the given @{code params} as <code>[0] ... [n]</code>.
+	 * 
+	 * @param expression must not be {@literal null}
+	 * @param context must not be {@literal null}
+	 * @param params must not be {@literal null}
+	 * @return
+	 */
+	public Object transform(String expression, AggregationOperationContext context, Object... params) {
+
+		Assert.notNull(expression, "Expression must not be null!");
+		Assert.notNull(context, "AggregationOperationContext must not be null!");
+		Assert.notNull(params, "Parameters must not be null!");
+
+		SpelExpression spelExpression = (SpelExpression) PARSER.parseExpression(expression);
+		ExpressionState state = new ExpressionState(new StandardEvaluationContext(params), CONFIG);
+		ExpressionNode node = ExpressionNode.from(spelExpression.getAST(), state);
+
+		return transform(new AggregationExpressionTransformationContext<ExpressionNode>(node, null, null, context));
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.spel.ExpressionTransformer#transform(org.springframework.data.mongodb.core.spel.ExpressionTransformationContextSupport)
+	 */
+	public Object transform(AggregationExpressionTransformationContext<ExpressionNode> context) {
+		return lookupConversionFor(context.getCurrentNode()).convert(context);
+	}
+
+	/**
+	 * Returns an appropriate {@link ExpressionNodeConversion} for the given {@code node}. Throws an
+	 * {@link IllegalArgumentException} if no conversion could be found.
+	 * 
+	 * @param node
+	 * @return the appropriate {@link ExpressionNodeConversion} for the given {@link ExpressionNode}.
+	 */
+	@SuppressWarnings("unchecked")
+	private ExpressionNodeConversion<ExpressionNode> lookupConversionFor(ExpressionNode node) {
+
+		for (ExpressionNodeConversion<? extends ExpressionNode> candidate : conversions) {
+			if (candidate.supports(node)) {
+				return (ExpressionNodeConversion<ExpressionNode>) candidate;
+			}
+		}
+
+		throw new IllegalArgumentException("Unsupported Element: " + node + " Type: " + node.getClass()
+				+ " You probably have a syntax error in your SpEL expression!");
+	}
+
+	/**
+	 * Abstract base class for {@link SpelNode} to (Db)-object conversions.
+	 * 
+	 * @author Thomas Darimont
+	 * @author Oliver Gierke
+	 */
+	private static abstract class ExpressionNodeConversion<T extends ExpressionNode> implements
+			AggregationExpressionTransformer {
+
+		private final AggregationExpressionTransformer transformer;
+		private final Class<? extends ExpressionNode> nodeType;
+
+		/**
+		 * Creates a new {@link ExpressionNodeConversion}.
+		 * 
+		 * @param transformer must not be {@literal null}.
+		 */
+		@SuppressWarnings("unchecked")
+		public ExpressionNodeConversion(AggregationExpressionTransformer transformer) {
+
+			Assert.notNull(transformer, "Transformer must not be null!");
+
+			this.nodeType = (Class<? extends ExpressionNode>) GenericTypeResolver.resolveTypeArgument(this.getClass(),
+					ExpressionNodeConversion.class);
+			this.transformer = transformer;
+		}
+
+		/**
+		 * Returns whether the current conversion supports the given {@link ExpressionNode}. By default we will match the
+		 * node type against the genric type the subclass types the type parameter to.
+		 * 
+		 * @param node will never be {@literal null}.
+		 * @return true if {@literal this} conversion can be applied to the given {@code node}.
+		 */
+		protected boolean supports(ExpressionNode node) {
+			return nodeType.equals(node.getClass());
+		}
+
+		/**
+		 * Triggers the transformation for the given {@link ExpressionNode} and the given current context.
+		 * 
+		 * @param node must not be {@literal null}.
+		 * @param context must not be {@literal null}.
+		 * @return
+		 */
+		protected Object transform(ExpressionNode node, AggregationExpressionTransformationContext<?> context) {
+
+			Assert.notNull(node, "ExpressionNode must not be null!");
+			Assert.notNull(context, "AggregationExpressionTransformationContext must not be null!");
+
+			return transform(node, context.getParentNode(), null, context);
+		}
+
+		/**
+		 * Triggers the transformation with the given new {@link ExpressionNode}, new parent node, the current operation and
+		 * the previous context.
+		 * 
+		 * @param node must not be {@literal null}.
+		 * @param parent
+		 * @param operation
+		 * @param context must not be {@literal null}.
+		 * @return
+		 */
+		protected Object transform(ExpressionNode node, ExpressionNode parent, DBObject operation,
+				AggregationExpressionTransformationContext<?> context) {
+
+			Assert.notNull(node, "ExpressionNode must not be null!");
+			Assert.notNull(context, "AggregationExpressionTransformationContext must not be null!");
+
+			return transform(new AggregationExpressionTransformationContext<ExpressionNode>(node, parent, operation,
+					context.getAggregationContext()));
+		}
+
+		/* 
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.SpelExpressionTransformer.NodeConversion#transform(org.springframework.data.mongodb.core.aggregation.AggregationExpressionTransformer.AggregationExpressionTransformationContext)
+		 */
+		@Override
+		public Object transform(AggregationExpressionTransformationContext<ExpressionNode> context) {
+			return transformer.transform(context);
+		}
+
+		/**
+		 * Performs the actual conversion from {@link SpelNode} to the corresponding representation for MongoDB.
+		 * 
+		 * @param context
+		 * @return
+		 */
+		protected abstract Object convert(AggregationExpressionTransformationContext<T> context);
+	}
+
+	/**
+	 * A {@link ExpressionNodeConversion} that converts arithmetic operations.
+	 * 
+	 * @author Thomas Darimont
+	 */
+	private static class OperatorNodeConversion extends ExpressionNodeConversion<OperatorNode> {
+
+		public OperatorNodeConversion(AggregationExpressionTransformer transformer) {
+			super(transformer);
+		}
+
+		/* 
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.SpelExpressionTransformer.SpelNodeWrapper#convertSpelNodeToMongoObjectExpression(org.springframework.data.mongodb.core.aggregation.SpelExpressionTransformer.ExpressionConversionContext)
+		 */
+		@Override
+		protected Object convert(AggregationExpressionTransformationContext<OperatorNode> context) {
+
+			OperatorNode currentNode = context.getCurrentNode();
+
+			DBObject operationObject = createOperationObjectAndAddToPreviousArgumentsIfNecessary(context, currentNode);
+			Object leftResult = transform(currentNode.getLeft(), currentNode, operationObject, context);
+
+			if (currentNode.isUnaryMinus()) {
+				return convertUnaryMinusOp(context, leftResult);
+			}
+
+			// we deliberately ignore the RHS result
+			transform(currentNode.getRight(), currentNode, operationObject, context);
+
+			return operationObject;
+		}
+
+		private DBObject createOperationObjectAndAddToPreviousArgumentsIfNecessary(
+				AggregationExpressionTransformationContext<OperatorNode> context, OperatorNode currentNode) {
+
+			DBObject nextDbObject = new BasicDBObject(currentNode.getMongoOperator(), new BasicDBList());
+
+			if (!context.hasPreviousOperation()) {
+				return nextDbObject;
+			}
+
+			if (context.parentIsSameOperation()) {
+
+				// same operator applied in a row e.g. 1 + 2 + 3 carry on with the operation and render as $add: [1, 2 ,3]
+				nextDbObject = context.getPreviousOperationObject();
+			} else if (!currentNode.isUnaryOperator()) {
+
+				// different operator -> add context object for next level to list if arguments of previous expression
+				context.addToPreviousOperation(nextDbObject);
+			}
+
+			return nextDbObject;
+		}
+
+		private Object convertUnaryMinusOp(ExpressionTransformationContextSupport<OperatorNode> context, Object leftResult) {
+
+			Object result = leftResult instanceof Number ? leftResult
+					: new BasicDBObject("$multiply", dbList(-1, leftResult));
+
+			if (leftResult != null && context.hasPreviousOperation()) {
+				context.addToPreviousOperation(result);
+			}
+
+			return result;
+		}
+
+		/* 
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.SpelExpressionTransformer.SpelNodeWrapper#supports(java.lang.Class)
+		 */
+		@Override
+		protected boolean supports(ExpressionNode node) {
+			return node.isMathematicalOperation();
+		}
+	}
+
+	/**
+	 * A {@link ExpressionNodeConversion} that converts indexed expressions.
+	 * 
+	 * @author Thomas Darimont
+	 * @author Oliver Gierke
+	 */
+	private static class IndexerNodeConversion extends ExpressionNodeConversion<ExpressionNode> {
+
+		public IndexerNodeConversion(AggregationExpressionTransformer transformer) {
+			super(transformer);
+		}
+
+		/* 
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.SpelExpressionTransformer.SpelNodeWrapper#convertSpelNodeToMongoObjectExpression(org.springframework.data.mongodb.core.aggregation.SpelExpressionTransformer.ExpressionConversionContext)
+		 */
+		@Override
+		protected Object convert(AggregationExpressionTransformationContext<ExpressionNode> context) {
+			return context.addToPreviousOrReturn(context.getCurrentNode().getValue());
+		}
+
+		/* 
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.SpelExpressionTransformer.NodeConversion#supports(org.springframework.data.mongodb.core.spel.ExpressionNode)
+		 */
+		@Override
+		protected boolean supports(ExpressionNode node) {
+			return node.isOfType(Indexer.class);
+		}
+	}
+
+	/**
+	 * A {@link ExpressionNodeConversion} that converts in-line list expressions.
+	 * 
+	 * @author Thomas Darimont
+	 */
+	private static class InlineListNodeConversion extends ExpressionNodeConversion<ExpressionNode> {
+
+		public InlineListNodeConversion(AggregationExpressionTransformer transformer) {
+			super(transformer);
+		}
+
+		/* 
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.SpelExpressionTransformer.SpelNodeWrapper#convertSpelNodeToMongoObjectExpression(org.springframework.data.mongodb.core.aggregation.SpelExpressionTransformer.ExpressionConversionContext)
+		 */
+		@Override
+		protected Object convert(AggregationExpressionTransformationContext<ExpressionNode> context) {
+
+			ExpressionNode currentNode = context.getCurrentNode();
+
+			if (!currentNode.hasChildren()) {
+				return null;
+			}
+
+			// just take the first item
+			return transform(currentNode.getChild(0), currentNode, null, context);
+		}
+
+		/* 
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.SpelExpressionTransformer.NodeConversion#supports(org.springframework.data.mongodb.core.spel.ExpressionNode)
+		 */
+		@Override
+		protected boolean supports(ExpressionNode node) {
+			return node.isOfType(InlineList.class);
+		}
+	}
+
+	/**
+	 * A {@link ExpressionNodeConversion} that converts property or field reference expressions.
+	 * 
+	 * @author Thomas Darimont
+	 * @author Oliver Gierke
+	 */
+	private static class PropertyOrFieldReferenceNodeConversion extends ExpressionNodeConversion<ExpressionNode> {
+
+		public PropertyOrFieldReferenceNodeConversion(AggregationExpressionTransformer transformer) {
+			super(transformer);
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.SpelExpressionTransformer.NodeConversion#convert(org.springframework.data.mongodb.core.aggregation.SpelExpressionTransformer.ExpressionTransformationContext)
+		 */
+		@Override
+		protected Object convert(AggregationExpressionTransformationContext<ExpressionNode> context) {
+
+			String fieldReference = context.getFieldReference().toString();
+			return context.addToPreviousOrReturn(fieldReference);
+		}
+
+		/* 
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.SpelExpressionTransformer.NodeConversion#supports(org.springframework.data.mongodb.core.spel.ExpressionNode)
+		 */
+		@Override
+		protected boolean supports(ExpressionNode node) {
+			return node.isOfType(PropertyOrFieldReference.class);
+		}
+	}
+
+	/**
+	 * A {@link ExpressionNodeConversion} that converts literal expressions.
+	 * 
+	 * @author Thomas Darimont
+	 * @author Oliver Gierke
+	 */
+	private static class LiteralNodeConversion extends ExpressionNodeConversion<LiteralNode> {
+
+		public LiteralNodeConversion(AggregationExpressionTransformer transformer) {
+			super(transformer);
+		}
+
+		/* 
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.SpelExpressionTransformer.SpelNodeWrapper#convertSpelNodeToMongoObjectExpression(org.springframework.data.mongodb.core.aggregation.SpelExpressionTransformer.ExpressionConversionContext)
+		 */
+		@Override
+		@SuppressWarnings("unchecked")
+		protected Object convert(AggregationExpressionTransformationContext<LiteralNode> context) {
+
+			LiteralNode node = context.getCurrentNode();
+			Object value = node.getValue();
+
+			if (context.hasPreviousOperation()) {
+
+				if (node.isUnaryMinus(context.getParentNode())) {
+					// unary minus operator
+					return NumberUtils.convertNumberToTargetClass(((Number) value).doubleValue() * -1,
+							(Class<Number>) value.getClass()); // retain type, e.g. int to -int
+				}
+
+				return context.addToPreviousOperation(value);
+			}
+
+			return value;
+		}
+
+		/* 
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.SpelExpressionTransformer.SpelNodeWrapper#supports(org.springframework.expression.spel.SpelNode)
+		 */
+		@Override
+		protected boolean supports(ExpressionNode node) {
+			return node.isLiteral();
+		}
+	}
+
+	/**
+	 * A {@link ExpressionNodeConversion} that converts method reference expressions.
+	 * 
+	 * @author Thomas Darimont
+	 * @author Oliver Gierke
+	 */
+	private static class MethodReferenceNodeConversion extends ExpressionNodeConversion<MethodReferenceNode> {
+
+		public MethodReferenceNodeConversion(AggregationExpressionTransformer transformer) {
+			super(transformer);
+		}
+
+		/* 
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.SpelExpressionTransformer.SpelNodeWrapper#convertSpelNodeToMongoObjectExpression(org.springframework.data.mongodb.core.aggregation.SpelExpressionTransformer.ExpressionConversionContext)
+		 */
+		@Override
+		protected Object convert(AggregationExpressionTransformationContext<MethodReferenceNode> context) {
+
+			MethodReferenceNode node = context.getCurrentNode();
+			List<Object> args = new ArrayList<Object>();
+
+			for (ExpressionNode childNode : node) {
+				args.add(transform(childNode, context));
+			}
+
+			return context.addToPreviousOrReturn(new BasicDBObject(node.getMethodName(), dbList(args.toArray())));
+		}
+	}
+
+	/**
+	 * A {@link ExpressionNodeConversion} that converts method compound expressions.
+	 * 
+	 * @author Thomas Darimont
+	 * @author Oliver Gierke
+	 */
+	private static class CompoundExpressionNodeConversion extends ExpressionNodeConversion<ExpressionNode> {
+
+		public CompoundExpressionNodeConversion(AggregationExpressionTransformer transformer) {
+			super(transformer);
+		}
+
+		/* 
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.SpelExpressionTransformer.SpelNodeWrapper#convertSpelNodeToMongoObjectExpression(org.springframework.data.mongodb.core.aggregation.SpelExpressionTransformer.ExpressionConversionContext)
+		 */
+		@Override
+		protected Object convert(AggregationExpressionTransformationContext<ExpressionNode> context) {
+
+			ExpressionNode currentNode = context.getCurrentNode();
+
+			if (currentNode.hasfirstChildNotOfType(Indexer.class)) {
+				// we have a property path expression like: foo.bar -> render as reference
+				return context.getFieldReference().toString();
+			}
+
+			return context.addToPreviousOrReturn(currentNode.getValue());
+		}
+
+		/* 
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.SpelExpressionTransformer.NodeConversion#supports(org.springframework.data.mongodb.core.spel.ExpressionNode)
+		 */
+		@Override
+		protected boolean supports(ExpressionNode node) {
+			return node.isOfType(CompoundExpression.class);
+		}
+	}
+}

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

@@ -0,0 +1,101 @@
+/*
+ * 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.
+ * 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 static org.springframework.data.mongodb.core.aggregation.Fields.*;
+
+import org.springframework.data.mapping.PropertyPath;
+import org.springframework.data.mapping.context.MappingContext;
+import org.springframework.data.mapping.context.PersistentPropertyPath;
+import org.springframework.data.mongodb.core.aggregation.ExposedFields.ExposedField;
+import org.springframework.data.mongodb.core.aggregation.ExposedFields.FieldReference;
+import org.springframework.data.mongodb.core.convert.QueryMapper;
+import org.springframework.data.mongodb.core.mapping.MongoPersistentEntity;
+import org.springframework.data.mongodb.core.mapping.MongoPersistentProperty;
+import org.springframework.util.Assert;
+
+import com.mongodb.DBObject;
+
+/**
+ * {@link AggregationOperationContext} aware of a particular type and a {@link MappingContext} to potentially translate
+ * property references into document field names.
+ * 
+ * @author Oliver Gierke
+ * @since 1.3
+ */
+public class TypeBasedAggregationOperationContext implements AggregationOperationContext {
+
+	private final Class<?> type;
+	private final MappingContext<? extends MongoPersistentEntity<?>, MongoPersistentProperty> mappingContext;
+	private final QueryMapper mapper;
+
+	/**
+	 * Creates a new {@link TypeBasedAggregationOperationContext} for the given type, {@link MappingContext} and
+	 * {@link QueryMapper}.
+	 * 
+	 * @param type must not be {@literal null}.
+	 * @param mappingContext must not be {@literal null}.
+	 * @param mapper must not be {@literal null}.
+	 */
+	public TypeBasedAggregationOperationContext(Class<?> type,
+			MappingContext<? extends MongoPersistentEntity<?>, MongoPersistentProperty> mappingContext, QueryMapper mapper) {
+
+		Assert.notNull(type, "Type must not be null!");
+		Assert.notNull(mappingContext, "MappingContext must not be null!");
+		Assert.notNull(mapper, "QueryMapper must not be null!");
+
+		this.type = type;
+		this.mappingContext = mappingContext;
+		this.mapper = mapper;
+	}
+
+	/* 
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperationContext#getMappedObject(com.mongodb.DBObject)
+	 */
+	@Override
+	public DBObject getMappedObject(DBObject dbObject) {
+		return mapper.getMappedObject(dbObject, mappingContext.getPersistentEntity(type));
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperationContext#getReference(org.springframework.data.mongodb.core.aggregation.Field)
+	 */
+	@Override
+	public FieldReference getReference(Field field) {
+
+		PropertyPath.from(field.getTarget(), type);
+		return getReferenceFor(field);
+	}
+
+	/* 
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperationContext#getReference(java.lang.String)
+	 */
+	@Override
+	public FieldReference getReference(String name) {
+
+		PersistentPropertyPath<MongoPersistentProperty> propertyPath = mappingContext.getPersistentPropertyPath(name, type);
+
+		return getReferenceFor(field(propertyPath.getLeafProperty().getName(),
+				propertyPath.toDotPath(MongoPersistentProperty.PropertyToFieldNameConverter.INSTANCE)));
+	}
+
+	private FieldReference getReferenceFor(Field field) {
+		return new FieldReference(new ExposedField(field, true));
+	}
+}

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

@@ -0,0 +1,51 @@
+/*
+ * 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.
+ * 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;
+
+/**
+ * A {@code TypedAggregation} is a special {@link Aggregation} that holds information of the input aggregation type.
+ * 
+ * @author Thomas Darimont
+ * @author Oliver Gierke
+ */
+public class TypedAggregation<I> extends Aggregation {
+
+	private final Class<I> inputType;
+
+	/**
+	 * Creates a new {@link TypedAggregation} from the given {@link AggregationOperation}s.
+	 * 
+	 * @param operations must not be {@literal null} or empty.
+	 */
+	public TypedAggregation(Class<I> inputType, AggregationOperation... operations) {
+
+		super(operations);
+
+		Assert.notNull(inputType, "Input type must not be null!");
+		this.inputType = inputType;
+	}
+
+	/**
+	 * Returns the input type for the {@link Aggregation}.
+	 * 
+	 * @return the inputType will never be {@literal null}.
+	 */
+	public Class<I> getInputType() {
+		return inputType;
+	}
+}

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

@@ -0,0 +1,55 @@
+/*
+ * 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.
+ * 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 $unwind}-operation.
+ * 
+ * @see http://docs.mongodb.org/manual/reference/aggregation/unwind/#pipe._S_unwind
+ * @author Thomas Darimont
+ * @author Oliver Gierke
+ * @since 1.3
+ */
+public class UnwindOperation implements AggregationOperation {
+
+	private final ExposedField field;
+
+	/**
+	 * Creates a new {@link UnwindOperation} for the given {@link Field}.
+	 * 
+	 * @param field must not be {@literal null}.
+	 */
+	public UnwindOperation(Field field) {
+
+		Assert.notNull(field);
+		this.field = new ExposedField(field, true);
+	}
+
+	/* 
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperation#toDBObject(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
+	 */
+	@Override
+	public DBObject toDBObject(AggregationOperationContext context) {
+		return new BasicDBObject("$unwind", context.getReference(field).toString());
+	}
+}

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

@@ -0,0 +1,5 @@
+/**
+ * Support for the MongoDB aggregation framework.
+ * @since 1.3
+ */
+package org.springframework.data.mongodb.core.aggregation;

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

@@ -19,6 +19,7 @@ import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.HashMap;
 import java.util.HashSet;
+import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Locale;
 import java.util.Map;
@@ -39,6 +40,7 @@ import org.springframework.data.convert.WritingConverter;
 import org.springframework.data.mapping.model.SimpleTypeHolder;
 import org.springframework.data.mongodb.core.convert.MongoConverters.BigDecimalToStringConverter;
 import org.springframework.data.mongodb.core.convert.MongoConverters.BigIntegerToStringConverter;
+import org.springframework.data.mongodb.core.convert.MongoConverters.DBObjectToStringConverter;
 import org.springframework.data.mongodb.core.convert.MongoConverters.StringToBigDecimalConverter;
 import org.springframework.data.mongodb.core.convert.MongoConverters.StringToBigIntegerConverter;
 import org.springframework.data.mongodb.core.convert.MongoConverters.StringToURLConverter;
@@ -85,12 +87,13 @@ public class CustomConversions {
 
 		Assert.notNull(converters);
 
-		this.readingPairs = new HashSet<ConvertiblePair>();
-		this.writingPairs = new HashSet<ConvertiblePair>();
+		this.readingPairs = new LinkedHashSet<ConvertiblePair>();
+		this.writingPairs = new LinkedHashSet<ConvertiblePair>();
 		this.customSimpleTypes = new HashSet<Class<?>>();
 		this.cache = new HashMap<Class<?>, HashMap<Class<?>, CacheValue>>();
 
 		this.converters = new ArrayList<Object>();
+		this.converters.addAll(converters);
 		this.converters.add(CustomToStringConverter.INSTANCE);
 		this.converters.add(BigDecimalToStringConverter.INSTANCE);
 		this.converters.add(StringToBigDecimalConverter.INSTANCE);
@@ -98,8 +101,8 @@ public class CustomConversions {
 		this.converters.add(StringToBigIntegerConverter.INSTANCE);
 		this.converters.add(URLToStringConverter.INSTANCE);
 		this.converters.add(StringToURLConverter.INSTANCE);
+		this.converters.add(DBObjectToStringConverter.INSTANCE);
 		this.converters.addAll(JodaTimeConverters.getConvertersToRegister());
-		this.converters.addAll(converters);
 
 		for (Object c : this.converters) {
 			registerConversion(c);
@@ -237,6 +240,7 @@ public class CustomConversions {
 	 * @return
 	 */
 	public Class<?> getCustomWriteTarget(Class<?> source, Class<?> expectedTargetType) {
+
 		Assert.notNull(source);
 		return getCustomTarget(source, expectedTargetType, writingPairs);
 	}

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

@@ -0,0 +1,123 @@
+/*
+ * 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.
+ * 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.convert;
+
+import java.util.Arrays;
+import java.util.Iterator;
+import java.util.Map;
+
+import org.springframework.data.mongodb.core.mapping.MongoPersistentProperty;
+import org.springframework.util.Assert;
+
+import com.mongodb.BasicDBObject;
+import com.mongodb.DBObject;
+
+/**
+ * Wrapper value object for a {@link BasicDBObject} to be able to access raw values by {@link MongoPersistentProperty}
+ * references. The accessors will transparently resolve nested document values that a {@link MongoPersistentProperty}
+ * might refer to through a path expression in field names.
+ * 
+ * @author Oliver Gierke
+ */
+class DBObjectAccessor {
+
+	private final DBObject dbObject;
+
+	/**
+	 * Creates a new {@link DBObjectAccessor} for the given {@link DBObject}.
+	 * 
+	 * @param dbObject must be a {@link BasicDBObject} effectively, must not be {@literal null}.
+	 */
+	public DBObjectAccessor(DBObject dbObject) {
+
+		Assert.notNull(dbObject, "DBObject must not be null!");
+		Assert.isInstanceOf(BasicDBObject.class, dbObject, "Given DBObject must be a BasicDBObject!");
+
+		this.dbObject = dbObject;
+	}
+
+	/**
+	 * Puts the given value into the backing {@link DBObject} based on the coordinates defined through the given
+	 * {@link MongoPersistentProperty}. By default this will be the plain field name. But field names might also consist
+	 * of path traversals so we might need to create intermediate {@link BasicDBObject}s.
+	 * 
+	 * @param prop must not be {@literal null}.
+	 * @param value
+	 */
+	public void put(MongoPersistentProperty prop, Object value) {
+
+		Assert.notNull(prop, "MongoPersistentProperty must not be null!");
+		String fieldName = prop.getFieldName();
+
+		Iterator<String> parts = Arrays.asList(fieldName.split("\\.")).iterator();
+		DBObject dbObject = this.dbObject;
+
+		while (parts.hasNext()) {
+
+			String part = parts.next();
+
+			if (parts.hasNext()) {
+				BasicDBObject nestedDbObject = new BasicDBObject();
+				dbObject.put(part, nestedDbObject);
+				dbObject = nestedDbObject;
+			} else {
+				dbObject.put(part, value);
+			}
+		}
+	}
+
+	/**
+	 * Returns the value the given {@link MongoPersistentProperty} refers to. By default this will be a direct field but
+	 * the method will also transparently resolve nested values the {@link MongoPersistentProperty} might refer to through
+	 * a path expression in the field name metadata.
+	 * 
+	 * @param property must not be {@literal null}.
+	 * @return
+	 */
+	@SuppressWarnings("unchecked")
+	public Object get(MongoPersistentProperty property) {
+
+		String fieldName = property.getFieldName();
+		Iterator<String> parts = Arrays.asList(fieldName.split("\\.")).iterator();
+		Map<Object, Object> source = this.dbObject.toMap();
+		Object result = null;
+
+		while (source != null && parts.hasNext()) {
+
+			result = source.get(parts.next());
+
+			if (parts.hasNext()) {
+				source = getAsMap(result);
+			}
+		}
+
+		return result;
+	}
+
+	@SuppressWarnings("unchecked")
+	private Map<Object, Object> getAsMap(Object source) {
+
+		if (source instanceof BasicDBObject) {
+			return ((DBObject) source).toMap();
+		}
+
+		if (source instanceof Map) {
+			return (Map<Object, Object>) source;
+		}
+
+		return null;
+	}
+}

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

@@ -0,0 +1,48 @@
+/*
+ * 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.
+ * 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.convert;
+
+import org.springframework.data.mongodb.core.mapping.MongoPersistentEntity;
+import org.springframework.data.mongodb.core.mapping.MongoPersistentProperty;
+
+import com.mongodb.DBRef;
+
+/**
+ * Used to resolve associations annotated with {@link org.springframework.data.mongodb.core.mapping.DBRef}.
+ * 
+ * @author Thomas Darimont
+ */
+public interface DbRefResolver {
+
+	/**
+	 * @param property will never be {@literal null}.
+	 * @param callback will never be {@literal null}.
+	 * @return
+	 */
+	Object resolveDbRef(MongoPersistentProperty property, DbRefResolverCallback callback);
+
+	/**
+	 * Creates a {@link DBRef} instance for the given {@link org.springframework.data.mongodb.core.mapping.DBRef}
+	 * annotation, {@link MongoPersistentEntity} and id.
+	 * 
+	 * @param annotation will never be {@literal null}.
+	 * @param entity will never be {@literal null}.
+	 * @param id will never be {@literal null}.
+	 * @return
+	 */
+	DBRef createDbRef(org.springframework.data.mongodb.core.mapping.DBRef annotation, MongoPersistentEntity<?> entity,
+			Object id);
+}

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

@@ -0,0 +1,35 @@
+/*
+ * 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.
+ * 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.convert;
+
+import org.springframework.data.mongodb.core.mapping.MongoPersistentProperty;
+
+/**
+ * Callback interface to be used in conjunction with {@link DbRefResolver}.
+ * 
+ * @author Thomas Darimont
+ * @author Oliver Gierke
+ */
+public interface DbRefResolverCallback {
+
+	/**
+	 * Resolve the final object for the given {@link MongoPersistentProperty}.
+	 * 
+	 * @param property will never be {@literal null}.
+	 * @return
+	 */
+	Object resolve(MongoPersistentProperty property);
+}

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

@@ -0,0 +1,282 @@
+/*
+ * 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.
+ * 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.convert;
+
+import java.io.IOException;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
+import java.io.Serializable;
+import java.lang.reflect.Method;
+
+import org.aopalliance.intercept.MethodInterceptor;
+import org.aopalliance.intercept.MethodInvocation;
+import org.objenesis.Objenesis;
+import org.objenesis.ObjenesisStd;
+import org.springframework.aop.framework.ProxyFactory;
+import org.springframework.cglib.proxy.Callback;
+import org.springframework.cglib.proxy.Enhancer;
+import org.springframework.cglib.proxy.Factory;
+import org.springframework.cglib.proxy.MethodProxy;
+import org.springframework.core.SpringVersion;
+import org.springframework.dao.DataAccessException;
+import org.springframework.dao.support.PersistenceExceptionTranslator;
+import org.springframework.data.mongodb.LazyLoadingException;
+import org.springframework.data.mongodb.MongoDbFactory;
+import org.springframework.data.mongodb.core.mapping.MongoPersistentEntity;
+import org.springframework.data.mongodb.core.mapping.MongoPersistentProperty;
+import org.springframework.util.Assert;
+import org.springframework.util.ClassUtils;
+import org.springframework.util.ReflectionUtils;
+import org.springframework.util.StringUtils;
+
+import com.mongodb.DB;
+import com.mongodb.DBRef;
+
+/**
+ * A {@link DbRefResolver} that resolves {@link org.springframework.data.mongodb.core.mapping.DBRef}s by delegating to a
+ * {@link DbRefResolverCallback} than is able to generate lazy loading proxies.
+ * 
+ * @author Thomas Darimont
+ * @author Oliver Gierke
+ */
+public class DefaultDbRefResolver implements DbRefResolver {
+
+	private static final boolean IS_SPRING_4_OR_BETTER = SpringVersion.getVersion().startsWith("4");
+	private static final boolean OBJENESIS_PRESENT = ClassUtils.isPresent("org.objenesis.Objenesis", null);
+
+	private final MongoDbFactory mongoDbFactory;
+	private final PersistenceExceptionTranslator exceptionTranslator;
+
+	/**
+	 * Creates a new {@link DefaultDbRefResolver} with the given {@link MongoDbFactory}.
+	 * 
+	 * @param mongoDbFactory must not be {@literal null}.
+	 */
+	public DefaultDbRefResolver(MongoDbFactory mongoDbFactory) {
+
+		Assert.notNull(mongoDbFactory, "MongoDbFactory translator must not be null!");
+
+		this.mongoDbFactory = mongoDbFactory;
+		this.exceptionTranslator = mongoDbFactory.getExceptionTranslator();
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.convert.DbRefResolver#resolveDbRef(org.springframework.data.mongodb.core.mapping.MongoPersistentProperty, org.springframework.data.mongodb.core.convert.DbRefResolverCallback)
+	 */
+	@Override
+	public Object resolveDbRef(MongoPersistentProperty property, DbRefResolverCallback callback) {
+
+		Assert.notNull(property, "Property must not be null!");
+		Assert.notNull(callback, "Callback must not be null!");
+
+		if (isLazyDbRef(property)) {
+			return createLazyLoadingProxy(property, callback);
+		}
+
+		return callback.resolve(property);
+	}
+
+	/* 
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.convert.DbRefResolver#created(org.springframework.data.mongodb.core.mapping.MongoPersistentProperty, org.springframework.data.mongodb.core.mapping.MongoPersistentEntity, java.lang.Object)
+	 */
+	@Override
+	public DBRef createDbRef(org.springframework.data.mongodb.core.mapping.DBRef annotation,
+			MongoPersistentEntity<?> entity, Object id) {
+
+		DB db = mongoDbFactory.getDb();
+		db = annotation != null && StringUtils.hasText(annotation.db()) ? mongoDbFactory.getDb(annotation.db()) : db;
+
+		return new DBRef(db, entity.getCollection(), id);
+	}
+
+	/**
+	 * Creates a proxy for the given {@link MongoPersistentProperty} using the given {@link DbRefResolverCallback} to
+	 * eventually resolve the value of the property.
+	 * 
+	 * @param property must not be {@literal null}.
+	 * @param callback must not be {@literal null}.
+	 * @return
+	 */
+	private Object createLazyLoadingProxy(MongoPersistentProperty property, DbRefResolverCallback callback) {
+
+		ProxyFactory proxyFactory = new ProxyFactory();
+		Class<?> propertyType = property.getType();
+
+		for (Class<?> type : propertyType.getInterfaces()) {
+			proxyFactory.addInterface(type);
+		}
+
+		LazyLoadingInterceptor interceptor = new LazyLoadingInterceptor(property, exceptionTranslator, callback);
+
+		if (propertyType.isInterface()) {
+			proxyFactory.addInterface(propertyType);
+			proxyFactory.addAdvice(interceptor);
+			return proxyFactory.getProxy();
+		}
+
+		proxyFactory.setProxyTargetClass(true);
+		proxyFactory.setTargetClass(propertyType);
+
+		if (IS_SPRING_4_OR_BETTER || !OBJENESIS_PRESENT) {
+			proxyFactory.addAdvice(interceptor);
+			return proxyFactory.getProxy();
+		}
+
+		return ObjenesisProxyEnhancer.enhanceAndGet(proxyFactory, propertyType, interceptor);
+	}
+
+	/**
+	 * @param property
+	 * @return
+	 */
+	private boolean isLazyDbRef(MongoPersistentProperty property) {
+		return property.getDBRef() != null && property.getDBRef().lazy();
+	}
+
+	/**
+	 * A {@link MethodInterceptor} that is used within a lazy loading proxy. The property resolving is delegated to a
+	 * {@link DbRefResolverCallback}. The resolving process is triggered by a method invocation on the proxy and is
+	 * guaranteed to be performed only once.
+	 * 
+	 * @author Thomas Darimont
+	 */
+	static class LazyLoadingInterceptor implements MethodInterceptor, org.springframework.cglib.proxy.MethodInterceptor,
+			Serializable {
+
+		private final DbRefResolverCallback callback;
+		private final MongoPersistentProperty property;
+		private final PersistenceExceptionTranslator exceptionTranslator;
+
+		private volatile boolean resolved;
+		private Object result;
+
+		/**
+		 * Creates a new {@link LazyLoadingInterceptor} for the given {@link MongoPersistentProperty},
+		 * {@link PersistenceExceptionTranslator} and {@link DbRefResolverCallback}.
+		 * 
+		 * @param property must not be {@literal null}.
+		 * @param callback must not be {@literal null}.
+		 */
+		public LazyLoadingInterceptor(MongoPersistentProperty property, PersistenceExceptionTranslator exceptionTranslator,
+				DbRefResolverCallback callback) {
+
+			Assert.notNull(property, "Property must not be null!");
+			Assert.notNull(exceptionTranslator, "Exception translator must not be null!");
+			Assert.notNull(callback, "Callback must not be null!");
+
+			this.callback = callback;
+			this.exceptionTranslator = exceptionTranslator;
+			this.property = property;
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.aopalliance.intercept.MethodInterceptor#invoke(org.aopalliance.intercept.MethodInvocation)
+		 */
+		@Override
+		public Object invoke(MethodInvocation invocation) throws Throwable {
+			return intercept(invocation.getThis(), invocation.getMethod(), invocation.getArguments(), null);
+		}
+
+		/* 
+		 * (non-Javadoc)
+		 * @see org.springframework.cglib.proxy.MethodInterceptor#intercept(java.lang.Object, java.lang.reflect.Method, java.lang.Object[], org.springframework.cglib.proxy.MethodProxy)
+		 */
+		@Override
+		public Object intercept(Object obj, Method method, Object[] args, MethodProxy proxy) throws Throwable {
+			return ReflectionUtils.isObjectMethod(method) ? method.invoke(obj, args) : method.invoke(ensureResolved(), args);
+		}
+
+		private Object ensureResolved() {
+
+			if (!resolved) {
+				this.result = resolve();
+				this.resolved = true;
+			}
+
+			return this.result;
+		}
+
+		private void writeObject(ObjectOutputStream out) throws IOException {
+
+			ensureResolved();
+			out.writeObject(this.result);
+		}
+
+		private void readObject(ObjectInputStream in) throws IOException {
+
+			try {
+				this.resolved = true; // Object is guaranteed to be resolved after serializations
+				this.result = in.readObject();
+			} catch (ClassNotFoundException e) {
+				throw new LazyLoadingException("Could not deserialize result", e);
+			}
+		}
+
+		/**
+		 * @return
+		 */
+		private synchronized Object resolve() {
+
+			if (!resolved) {
+
+				try {
+
+					return callback.resolve(property);
+
+				} catch (RuntimeException ex) {
+
+					DataAccessException translatedException = this.exceptionTranslator.translateExceptionIfPossible(ex);
+					throw new LazyLoadingException("Unable to lazily resolve DBRef!", translatedException);
+				}
+			}
+
+			return result;
+		}
+
+		public boolean isResolved() {
+			return resolved;
+		}
+
+		public Object getResult() {
+			return result;
+		}
+	}
+
+	/**
+	 * Static class to accomodate optional dependency on Objenesis.
+	 * 
+	 * @author Oliver Gierke
+	 */
+	private static class ObjenesisProxyEnhancer {
+
+		private static final Objenesis OBJENESIS = new ObjenesisStd(true);
+
+		public static Object enhanceAndGet(ProxyFactory proxyFactory, Class<?> type,
+				org.springframework.cglib.proxy.MethodInterceptor interceptor) {
+
+			Enhancer enhancer = new Enhancer();
+			enhancer.setSuperclass(type);
+			enhancer.setCallbackType(org.springframework.cglib.proxy.MethodInterceptor.class);
+
+			Factory factory = (Factory) OBJENESIS.newInstance(enhancer.createClass());
+			factory.setCallbacks(new Callback[] { interceptor });
+			return factory;
+		}
+	}
+}

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2011 the original author or authors.
+ * Copyright 2011-2013 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.
@@ -18,16 +18,19 @@ package org.springframework.data.mongodb.core.convert;
 import java.util.Arrays;
 import java.util.List;
 import java.util.Map;
+import java.util.Set;
 
-import org.springframework.data.convert.SimpleTypeInformationMapper;
 import org.springframework.data.convert.DefaultTypeMapper;
+import org.springframework.data.convert.SimpleTypeInformationMapper;
 import org.springframework.data.convert.TypeAliasAccessor;
 import org.springframework.data.convert.TypeInformationMapper;
 import org.springframework.data.mapping.PersistentEntity;
 import org.springframework.data.mapping.context.MappingContext;
 import org.springframework.data.util.ClassTypeInformation;
 import org.springframework.data.util.TypeInformation;
+
 import com.mongodb.BasicDBList;
+import com.mongodb.BasicDBObject;
 import com.mongodb.DBObject;
 
 /**
@@ -37,33 +40,43 @@ import com.mongodb.DBObject;
  * respectively.
  * 
  * @author Oliver Gierke
+ * @author Thomas Darimont
  */
 public class DefaultMongoTypeMapper extends DefaultTypeMapper<DBObject> implements MongoTypeMapper {
 
 	public static final String DEFAULT_TYPE_KEY = "_class";
-	@SuppressWarnings("rawtypes")
+	@SuppressWarnings("rawtypes")//
 	private static final TypeInformation<List> LIST_TYPE_INFO = ClassTypeInformation.from(List.class);
-	@SuppressWarnings("rawtypes")
+	@SuppressWarnings("rawtypes")//
 	private static final TypeInformation<Map> MAP_TYPE_INFO = ClassTypeInformation.from(Map.class);
-	private String typeKey = DEFAULT_TYPE_KEY;
+
+	private final TypeAliasAccessor<DBObject> accessor;
+	private final String typeKey;
 
 	public DefaultMongoTypeMapper() {
-		this(DEFAULT_TYPE_KEY, Arrays.asList(SimpleTypeInformationMapper.INSTANCE));
+		this(DEFAULT_TYPE_KEY);
 	}
 
 	public DefaultMongoTypeMapper(String typeKey) {
-		super(new DBObjectTypeAliasAccessor(typeKey));
-		this.typeKey = typeKey;
+		this(typeKey, Arrays.asList(SimpleTypeInformationMapper.INSTANCE));
 	}
 
 	public DefaultMongoTypeMapper(String typeKey, MappingContext<? extends PersistentEntity<?, ?>, ?> mappingContext) {
-		super(new DBObjectTypeAliasAccessor(typeKey), mappingContext, Arrays.asList(SimpleTypeInformationMapper.INSTANCE));
-		this.typeKey = typeKey;
+		this(typeKey, new DBObjectTypeAliasAccessor(typeKey), mappingContext, Arrays
+				.asList(SimpleTypeInformationMapper.INSTANCE));
 	}
 
 	public DefaultMongoTypeMapper(String typeKey, List<? extends TypeInformationMapper> mappers) {
-		super(new DBObjectTypeAliasAccessor(typeKey), mappers);
+		this(typeKey, new DBObjectTypeAliasAccessor(typeKey), null, mappers);
+	}
+
+	private DefaultMongoTypeMapper(String typeKey, TypeAliasAccessor<DBObject> accessor,
+			MappingContext<? extends PersistentEntity<?, ?>, ?> mappingContext, List<? extends TypeInformationMapper> mappers) {
+
+		super(accessor, mappingContext, mappers);
+
 		this.typeKey = typeKey;
+		this.accessor = accessor;
 	}
 
 	/*
@@ -74,6 +87,31 @@ public class DefaultMongoTypeMapper extends DefaultTypeMapper<DBObject> implemen
 		return typeKey == null ? false : typeKey.equals(key);
 	}
 
+	/* 
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.convert.MongoTypeMapper#writeTypeRestrictions(java.util.Set)
+	 */
+	@Override
+	public void writeTypeRestrictions(DBObject result, Set<Class<?>> restrictedTypes) {
+
+		if (restrictedTypes == null || restrictedTypes.isEmpty()) {
+			return;
+		}
+
+		BasicDBList restrictedMappedTypes = new BasicDBList();
+
+		for (Class<?> restrictedType : restrictedTypes) {
+
+			Object typeAlias = getAliasFor(ClassTypeInformation.from(restrictedType));
+
+			if (typeAlias != null) {
+				restrictedMappedTypes.add(typeAlias);
+			}
+		}
+
+		accessor.writeTypeTo(result, new BasicDBObject("$in", restrictedMappedTypes));
+	}
+
 	/* (non-Javadoc)
 	 * @see org.springframework.data.convert.DefaultTypeMapper#getFallbackTypeFor(java.lang.Object)
 	 */
@@ -83,6 +121,7 @@ public class DefaultMongoTypeMapper extends DefaultTypeMapper<DBObject> implemen
 	}
 
 	/**
+	 * {@link TypeAliasAccessor} to store aliases in a {@link DBObject}.
 	 * 
 	 * @author Oliver Gierke
 	 */

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

@@ -57,11 +57,9 @@ import org.springframework.data.util.TypeInformation;
 import org.springframework.expression.spel.standard.SpelExpressionParser;
 import org.springframework.util.Assert;
 import org.springframework.util.CollectionUtils;
-import org.springframework.util.StringUtils;
 
 import com.mongodb.BasicDBList;
 import com.mongodb.BasicDBObject;
-import com.mongodb.DB;
 import com.mongodb.DBObject;
 import com.mongodb.DBRef;
 
@@ -72,6 +70,7 @@ import com.mongodb.DBRef;
  * @author Oliver Gierke
  * @author Jon Brisbin
  * @author Patrik Wasik
+ * @author Thomas Darimont
  */
 public class MappingMongoConverter extends AbstractMongoConverter implements ApplicationContextAware {
 
@@ -79,8 +78,8 @@ public class MappingMongoConverter extends AbstractMongoConverter implements App
 
 	protected final MappingContext<? extends MongoPersistentEntity<?>, MongoPersistentProperty> mappingContext;
 	protected final SpelExpressionParser spelExpressionParser = new SpelExpressionParser();
-	protected final MongoDbFactory mongoDbFactory;
 	protected final QueryMapper idMapper;
+	protected final DbRefResolver dbRefResolver;
 	protected ApplicationContext applicationContext;
 	protected boolean useFieldAccessOnly = true;
 	protected MongoTypeMapper typeMapper;
@@ -89,21 +88,21 @@ public class MappingMongoConverter extends AbstractMongoConverter implements App
 	private SpELContext spELContext;
 
 	/**
-	 * Creates a new {@link MappingMongoConverter} given the new {@link MongoDbFactory} and {@link MappingContext}.
+	 * Creates a new {@link MappingMongoConverter} given the new {@link DbRefResolver} and {@link MappingContext}.
 	 * 
 	 * @param mongoDbFactory must not be {@literal null}.
 	 * @param mappingContext must not be {@literal null}.
 	 */
 	@SuppressWarnings("deprecation")
-	public MappingMongoConverter(MongoDbFactory mongoDbFactory,
+	public MappingMongoConverter(DbRefResolver dbRefResolver,
 			MappingContext<? extends MongoPersistentEntity<?>, MongoPersistentProperty> mappingContext) {
 
 		super(ConversionServiceFactory.createDefaultConversionService());
 
-		Assert.notNull(mongoDbFactory);
-		Assert.notNull(mappingContext);
+		Assert.notNull(dbRefResolver, "DbRefResolver must not be null!");
+		Assert.notNull(mappingContext, "MappingContext must not be null!");
 
-		this.mongoDbFactory = mongoDbFactory;
+		this.dbRefResolver = dbRefResolver;
 		this.mappingContext = mappingContext;
 		this.typeMapper = new DefaultMongoTypeMapper(DefaultMongoTypeMapper.DEFAULT_TYPE_KEY, mappingContext);
 		this.idMapper = new QueryMapper(this);
@@ -111,6 +110,19 @@ public class MappingMongoConverter extends AbstractMongoConverter implements App
 		this.spELContext = new SpELContext(DBObjectPropertyAccessor.INSTANCE);
 	}
 
+	/**
+	 * Creates a new {@link MappingMongoConverter} given the new {@link MongoDbFactory} and {@link MappingContext}.
+	 * 
+	 * @deprecated use the constructor taking a {@link DbRefResolver} instead.
+	 * @param mongoDbFactory must not be {@literal null}.
+	 * @param mappingContext must not be {@literal null}.
+	 */
+	@Deprecated
+	public MappingMongoConverter(MongoDbFactory mongoDbFactory,
+			MappingContext<? extends MongoPersistentEntity<?>, MongoPersistentProperty> mappingContext) {
+		this(new DefaultDbRefResolver(mongoDbFactory), mappingContext);
+	}
+
 	/**
 	 * Configures the {@link MongoTypeMapper} to be used to add type information to {@link DBObject}s created by the
 	 * converter and how to lookup type information from {@link DBObject}s when reading them. Uses a
@@ -124,6 +136,15 @@ public class MappingMongoConverter extends AbstractMongoConverter implements App
 				mappingContext) : typeMapper;
 	}
 
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.convert.MongoConverter#getTypeMapper()
+	 */
+	@Override
+	public MongoTypeMapper getTypeMapper() {
+		return this.typeMapper;
+	}
+
 	/**
 	 * Configure the characters dots potentially contained in a {@link Map} shall be replaced with. By default we don't do
 	 * any translation but rather reject a {@link Map} with keys containing dots causing the conversion for the entire
@@ -224,7 +245,7 @@ public class MappingMongoConverter extends AbstractMongoConverter implements App
 				parent);
 	}
 
-	private <S extends Object> S read(final MongoPersistentEntity<S> entity, final DBObject dbo, Object parent) {
+	private <S extends Object> S read(final MongoPersistentEntity<S> entity, final DBObject dbo, final Object parent) {
 
 		final DefaultSpELExpressionEvaluator evaluator = new DefaultSpELExpressionEvaluator(dbo, spELContext);
 
@@ -251,11 +272,18 @@ public class MappingMongoConverter extends AbstractMongoConverter implements App
 		// Handle associations
 		entity.doWithAssociations(new AssociationHandler<MongoPersistentProperty>() {
 			public void doWithAssociation(Association<MongoPersistentProperty> association) {
+
 				MongoPersistentProperty inverseProp = association.getInverse();
-				Object obj = getValueInternal(inverseProp, dbo, evaluator, result);
+
+				Object obj = dbRefResolver.resolveDbRef(inverseProp, new DbRefResolverCallback() {
+
+					@Override
+					public Object resolve(MongoPersistentProperty property) {
+						return getValueInternal(property, dbo, evaluator, parent);
+					}
+				});
 
 				wrapper.setProperty(inverseProp, obj);
-
 			}
 		});
 
@@ -356,8 +384,7 @@ public class MappingMongoConverter extends AbstractMongoConverter implements App
 			try {
 				Object id = wrapper.getProperty(idProperty, Object.class, fieldAccessOnly);
 				dbo.put("_id", idMapper.convertId(id));
-			} catch (ConversionException ignored) {
-			}
+			} catch (ConversionException ignored) {}
 		}
 
 		// Write the properties
@@ -376,7 +403,7 @@ public class MappingMongoConverter extends AbstractMongoConverter implements App
 					if (!conversions.isSimpleType(propertyObj.getClass())) {
 						writePropertyInternal(propertyObj, dbo, prop);
 					} else {
-						writeSimpleInternal(propertyObj, dbo, prop.getFieldName());
+						writeSimpleInternal(propertyObj, dbo, prop);
 					}
 				}
 			}
@@ -401,26 +428,27 @@ public class MappingMongoConverter extends AbstractMongoConverter implements App
 			return;
 		}
 
-		String name = prop.getFieldName();
+		DBObjectAccessor accessor = new DBObjectAccessor(dbo);
+
 		TypeInformation<?> valueType = ClassTypeInformation.from(obj.getClass());
 		TypeInformation<?> type = prop.getTypeInformation();
 
 		if (valueType.isCollectionLike()) {
 			DBObject collectionInternal = createCollection(asCollection(obj), prop);
-			dbo.put(name, collectionInternal);
+			accessor.put(prop, collectionInternal);
 			return;
 		}
 
 		if (valueType.isMap()) {
 			DBObject mapDbObj = createMap((Map<Object, Object>) obj, prop);
-			dbo.put(name, mapDbObj);
+			accessor.put(prop, mapDbObj);
 			return;
 		}
 
 		if (prop.isDbReference()) {
 			DBRef dbRefObj = createDBRef(obj, prop.getDBRef());
 			if (null != dbRefObj) {
-				dbo.put(name, dbRefObj);
+				accessor.put(prop, dbRefObj);
 				return;
 			}
 		}
@@ -429,18 +457,20 @@ public class MappingMongoConverter extends AbstractMongoConverter implements App
 		Class<?> basicTargetType = conversions.getCustomWriteTarget(obj.getClass(), null);
 
 		if (basicTargetType != null) {
-			dbo.put(name, conversionService.convert(obj, basicTargetType));
+			accessor.put(prop, conversionService.convert(obj, basicTargetType));
 			return;
 		}
 
-		BasicDBObject propDbObj = new BasicDBObject();
+		Object existingValue = accessor.get(prop);
+		BasicDBObject propDbObj = existingValue instanceof BasicDBObject ? (BasicDBObject) existingValue
+				: new BasicDBObject();
 		addCustomTypeKeyIfNecessary(type, obj, propDbObj);
 
 		MongoPersistentEntity<?> entity = isSubtype(prop.getType(), obj.getClass()) ? mappingContext
 				.getPersistentEntity(obj.getClass()) : mappingContext.getPersistentEntity(type);
 
 		writeInternal(obj, propDbObj, entity);
-		dbo.put(name, propDbObj);
+		accessor.put(prop, propDbObj);
 	}
 
 	private boolean isSubtype(Class<?> left, Class<?> right) {
@@ -658,6 +688,11 @@ public class MappingMongoConverter extends AbstractMongoConverter implements App
 		dbObject.put(key, getPotentiallyConvertedSimpleWrite(value));
 	}
 
+	private void writeSimpleInternal(Object value, DBObject dbObject, MongoPersistentProperty property) {
+		DBObjectAccessor accessor = new DBObjectAccessor(dbObject);
+		accessor.put(property, getPotentiallyConvertedSimpleWrite(value));
+	}
+
 	/**
 	 * Checks whether we have a custom conversion registered for the given value into an arbitrary simple Mongo type.
 	 * Returns the converted value if so. If not, we perform special enum handling or simply return the value as is.
@@ -733,10 +768,7 @@ public class MappingMongoConverter extends AbstractMongoConverter implements App
 			throw new MappingException("Cannot create a reference to an object with a NULL id.");
 		}
 
-		DB db = mongoDbFactory.getDb();
-		db = dbref != null && StringUtils.hasText(dbref.db()) ? mongoDbFactory.getDb(dbref.db()) : db;
-
-		return new DBRef(db, targetEntity.getCollection(), idMapper.convertId(id));
+		return dbRefResolver.createDbRef(dbref, targetEntity, idMapper.convertId(id));
 	}
 
 	protected Object getValueInternal(MongoPersistentProperty prop, DBObject dbo, SpELExpressionEvaluator eval,
@@ -776,7 +808,7 @@ public class MappingMongoConverter extends AbstractMongoConverter implements App
 			Object dbObjItem = sourceValue.get(i);
 
 			if (dbObjItem instanceof DBRef) {
-				items.add(DBRef.class.equals(rawComponentType) ? dbObjItem : read(componentType, ((DBRef) dbObjItem).fetch(),
+				items.add(DBRef.class.equals(rawComponentType) ? dbObjItem : read(componentType, readRef((DBRef) dbObjItem),
 						parent));
 			} else if (dbObjItem instanceof DBObject) {
 				items.add(read(componentType, (DBObject) dbObjItem, parent));
@@ -824,7 +856,7 @@ public class MappingMongoConverter extends AbstractMongoConverter implements App
 			if (value instanceof DBObject) {
 				map.put(key, read(valueType, (DBObject) value, parent));
 			} else if (value instanceof DBRef) {
-				map.put(key, DBRef.class.equals(rawValueType) ? value : read(valueType, ((DBRef) value).fetch()));
+				map.put(key, DBRef.class.equals(rawValueType) ? value : read(valueType, readRef((DBRef) value)));
 			} else {
 				Class<?> valueClass = valueType == null ? null : valueType.getType();
 				map.put(key, getPotentiallyConvertedSimpleRead(value, valueClass));
@@ -956,7 +988,7 @@ public class MappingMongoConverter extends AbstractMongoConverter implements App
 
 	private class MongoDbPropertyValueProvider implements PropertyValueProvider<MongoPersistentProperty> {
 
-		private final DBObject source;
+		private final DBObjectAccessor source;
 		private final SpELExpressionEvaluator evaluator;
 		private final Object parent;
 
@@ -969,7 +1001,7 @@ public class MappingMongoConverter extends AbstractMongoConverter implements App
 			Assert.notNull(source);
 			Assert.notNull(evaluator);
 
-			this.source = source;
+			this.source = new DBObjectAccessor(source);
 			this.evaluator = evaluator;
 			this.parent = parent;
 		}
@@ -981,7 +1013,7 @@ public class MappingMongoConverter extends AbstractMongoConverter implements App
 		public <T> T getPropertyValue(MongoPersistentProperty property) {
 
 			String expression = property.getSpelExpression();
-			Object value = expression != null ? evaluator.evaluate(expression) : source.get(property.getFieldName());
+			Object value = expression != null ? evaluator.evaluate(expression) : source.get(property);
 
 			if (value == null) {
 				return null;
@@ -1034,7 +1066,7 @@ public class MappingMongoConverter extends AbstractMongoConverter implements App
 		if (conversions.hasCustomReadTarget(value.getClass(), rawType)) {
 			return (T) conversionService.convert(value, rawType);
 		} else if (value instanceof DBRef) {
-			return (T) (rawType.equals(DBRef.class) ? value : read(type, ((DBRef) value).fetch(), parent));
+			return (T) (rawType.equals(DBRef.class) ? value : read(type, readRef((DBRef) value), parent));
 		} else if (value instanceof BasicDBList) {
 			return (T) readCollectionOrArray(type, (BasicDBList) value, parent);
 		} else if (value instanceof DBObject) {
@@ -1043,4 +1075,14 @@ public class MappingMongoConverter extends AbstractMongoConverter implements App
 			return (T) getPotentiallyConvertedSimpleRead(value, rawType);
 		}
 	}
+
+	/**
+	 * Performs the fetch operation for the given {@link DBRef}.
+	 * 
+	 * @param ref
+	 * @return
+	 */
+	DBObject readRef(DBRef ref) {
+		return ref.fetch();
+	}
 }

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2011 the original author or authors.
+ * Copyright 2010-2013 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.
@@ -17,6 +17,7 @@ package org.springframework.data.mongodb.core.convert;
 
 import org.springframework.data.convert.EntityConverter;
 import org.springframework.data.convert.EntityReader;
+import org.springframework.data.convert.TypeMapper;
 import org.springframework.data.mongodb.core.mapping.MongoPersistentEntity;
 import org.springframework.data.mongodb.core.mapping.MongoPersistentProperty;
 
@@ -26,9 +27,17 @@ import com.mongodb.DBObject;
  * Central Mongo specific converter interface which combines {@link MongoWriter} and {@link MongoReader}.
  * 
  * @author Oliver Gierke
+ * @author Thomas Darimont
  */
 public interface MongoConverter extends
 		EntityConverter<MongoPersistentEntity<?>, MongoPersistentProperty, Object, DBObject>, MongoWriter<Object>,
 		EntityReader<Object, DBObject> {
 
+	/**
+	 * Returns thw {@link TypeMapper} being used to write type information into {@link DBObject}s created with that
+	 * converter.
+	 * 
+	 * @return will never be {@literal null}.
+	 */
+	MongoTypeMapper getTypeMapper();
 }

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

@@ -24,8 +24,11 @@ import org.bson.types.ObjectId;
 import org.springframework.core.convert.ConversionFailedException;
 import org.springframework.core.convert.TypeDescriptor;
 import org.springframework.core.convert.converter.Converter;
+import org.springframework.data.convert.ReadingConverter;
 import org.springframework.util.StringUtils;
 
+import com.mongodb.DBObject;
+
 /**
  * Wrapper class to contain useful converters for the usage with Mongo.
  * 
@@ -147,4 +150,15 @@ abstract class MongoConverters {
 			}
 		}
 	}
+
+	@ReadingConverter
+	public static enum DBObjectToStringConverter implements Converter<DBObject, String> {
+
+		INSTANCE;
+
+		@Override
+		public String convert(DBObject source) {
+			return source == null ? null : source.toString();
+		}
+	}
 }

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

@@ -15,6 +15,8 @@
  */
 package org.springframework.data.mongodb.core.convert;
 
+import java.util.Set;
+
 import org.springframework.data.convert.TypeMapper;
 
 import com.mongodb.DBObject;
@@ -32,4 +34,14 @@ public interface MongoTypeMapper extends TypeMapper<DBObject> {
 	 * @return
 	 */
 	boolean isTypeKey(String key);
+
+	/**
+	 * Writes type restrictions to the given {@link DBObject}. This usually results in an {@code $in}-clause to be
+	 * generated that restricts the type-key (e.g. {@code _class}) to be in the set of type aliases for the given
+	 * {@code restrictedTypes}.
+	 * 
+	 * @param result must not be {@literal null}
+	 * @param restrictedTypes must not be {@literal null}
+	 */
+	void writeTypeRestrictions(DBObject result, Set<Class<?>> restrictedTypes);
 }

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

@@ -18,6 +18,7 @@ package org.springframework.data.mongodb.core.convert;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
+import java.util.Set;
 
 import org.bson.types.ObjectId;
 import org.springframework.core.convert.ConversionException;
@@ -29,6 +30,7 @@ import org.springframework.data.mapping.context.MappingContext;
 import org.springframework.data.mapping.context.PersistentPropertyPath;
 import org.springframework.data.mongodb.core.mapping.MongoPersistentEntity;
 import org.springframework.data.mongodb.core.mapping.MongoPersistentProperty;
+import org.springframework.data.mongodb.core.query.Query;
 import org.springframework.util.Assert;
 
 import com.mongodb.BasicDBList;
@@ -46,7 +48,6 @@ import com.mongodb.DBRef;
 public class QueryMapper {
 
 	private static final List<String> DEFAULT_ID_NAMES = Arrays.asList("id", "_id");
-	private static final String N_OR_PATTERN = "\\$.*or";
 
 	private final ConversionService conversionService;
 	private final MongoConverter converter;
@@ -74,9 +75,10 @@ public class QueryMapper {
 	 * @param entity can be {@literal null}.
 	 * @return
 	 */
+	@SuppressWarnings("deprecation")
 	public DBObject getMappedObject(DBObject query, MongoPersistentEntity<?> entity) {
 
-		if (Keyword.isKeyword(query)) {
+		if (isNestedKeyword(query)) {
 			return getMappedKeyword(new Keyword(query), entity);
 		}
 
@@ -84,8 +86,32 @@ public class QueryMapper {
 
 		for (String key : query.keySet()) {
 
+			// TODO: remove one once QueryMapper can work with Query instances directly
+			if (Query.isRestrictedTypeKey(key)) {
+
+				@SuppressWarnings("unchecked")
+				Set<Class<?>> restrictedTypes = (Set<Class<?>>) query.get(key);
+				this.converter.getTypeMapper().writeTypeRestrictions(result, restrictedTypes);
+
+				continue;
+			}
+
+			if (isKeyword(key)) {
+				result.putAll(getMappedKeyword(new Keyword(query, key), entity));
+				continue;
+			}
+
 			Field field = entity == null ? new Field(key) : new MetadataBackedField(key, entity, mappingContext);
-			result.put(field.getMappedKey(), getMappedValue(query.get(key), field));
+
+			Object rawValue = query.get(key);
+			String newKey = field.getMappedKey();
+
+			if (isNestedKeyword(rawValue) && !field.isIdField()) {
+				Keyword keyword = new Keyword((DBObject) rawValue);
+				result.put(newKey, getMappedKeyword(field, keyword));
+			} else {
+				result.put(newKey, getMappedValue(field, rawValue));
+			}
 		}
 
 		return result;
@@ -94,59 +120,62 @@ public class QueryMapper {
 	/**
 	 * Returns the given {@link DBObject} representing a keyword by mapping the keyword's value.
 	 * 
-	 * @param query the {@link DBObject} representing a keyword (e.g. {@code $ne : … } )
+	 * @param keyword the {@link DBObject} representing a keyword (e.g. {@code $ne : … } )
 	 * @param entity
 	 * @return
 	 */
-	private DBObject getMappedKeyword(Keyword query, MongoPersistentEntity<?> entity) {
+	private DBObject getMappedKeyword(Keyword keyword, MongoPersistentEntity<?> entity) {
 
 		// $or/$nor
-		if (query.key.matches(N_OR_PATTERN)) {
+		if (keyword.isOrOrNor() || keyword.hasIterableValue()) {
 
-			Iterable<?> conditions = (Iterable<?>) query.value;
+			Iterable<?> conditions = keyword.getValue();
 			BasicDBList newConditions = new BasicDBList();
 
 			for (Object condition : conditions) {
-				newConditions.add(getMappedObject((DBObject) condition, entity));
+				newConditions.add(condition instanceof DBObject ? getMappedObject((DBObject) condition, entity)
+						: convertSimpleOrDBObject(condition, entity));
 			}
 
-			return new BasicDBObject(query.key, newConditions);
+			return new BasicDBObject(keyword.getKey(), newConditions);
 		}
 
-		return new BasicDBObject(query.key, convertSimpleOrDBObject(query.value, entity));
+		return new BasicDBObject(keyword.getKey(), convertSimpleOrDBObject(keyword.getValue(), entity));
 	}
 
 	/**
 	 * Returns the mapped keyword considered defining a criteria for the given property.
 	 * 
-	 * @param keyword
 	 * @param property
+	 * @param keyword
 	 * @return
 	 */
-	public DBObject getMappedKeyword(Keyword keyword, Field property) {
+	private DBObject getMappedKeyword(Field property, Keyword keyword) {
 
-		if (property.isAssociation()) {
-			convertAssociation(keyword.value, property.getProperty());
-		}
+		boolean needsAssociationConversion = property.isAssociation() && !keyword.isExists();
+		Object value = keyword.getValue();
 
-		return new BasicDBObject(keyword.key, getMappedValue(keyword.value, property.with(keyword.key)));
+		Object convertedValue = needsAssociationConversion ? convertAssociation(value, property.getProperty())
+				: getMappedValue(property.with(keyword.getKey()), value);
+
+		return new BasicDBObject(keyword.key, convertedValue);
 	}
 
 	/**
 	 * Returns the mapped value for the given source object assuming it's a value for the given
 	 * {@link MongoPersistentProperty}.
 	 * 
-	 * @param source the source object to be mapped
+	 * @param value the source object to be mapped
 	 * @param property the property the value is a value for
 	 * @param newKey the key the value will be bound to eventually
 	 * @return
 	 */
-	private Object getMappedValue(Object source, Field key) {
+	private Object getMappedValue(Field documentField, Object value) {
 
-		if (key.isIdField()) {
+		if (documentField.isIdField()) {
 
-			if (source instanceof DBObject) {
-				DBObject valueDbo = (DBObject) source;
+			if (value instanceof DBObject) {
+				DBObject valueDbo = (DBObject) value;
 				if (valueDbo.containsField("$in") || valueDbo.containsField("$nin")) {
 					String inKey = valueDbo.containsField("$in") ? "$in" : "$nin";
 					List<Object> ids = new ArrayList<Object>();
@@ -157,22 +186,25 @@ public class QueryMapper {
 				} else if (valueDbo.containsField("$ne")) {
 					valueDbo.put("$ne", convertId(valueDbo.get("$ne")));
 				} else {
-					return getMappedObject((DBObject) source, null);
+					return getMappedObject((DBObject) value, null);
 				}
 
 				return valueDbo;
 
 			} else {
-				return convertId(source);
+				return convertId(value);
 			}
 		}
 
-		if (key.isAssociation()) {
-			return Keyword.isKeyword(source) ? getMappedKeyword(new Keyword(source), key) : convertAssociation(source,
-					key.getProperty());
+		if (isNestedKeyword(value)) {
+			return getMappedKeyword(new Keyword((DBObject) value), null);
 		}
 
-		return convertSimpleOrDBObject(source, key.getPropertyEntity());
+		if (documentField.isAssociation()) {
+			return convertAssociation(value, documentField.getProperty());
+		}
+
+		return convertSimpleOrDBObject(value, documentField.getPropertyEntity());
 	}
 
 	/**
@@ -185,18 +217,30 @@ public class QueryMapper {
 	private Object convertSimpleOrDBObject(Object source, MongoPersistentEntity<?> entity) {
 
 		if (source instanceof BasicDBList) {
-			return converter.convertToMongoType(source);
+			return delegateConvertToMongoType(source, entity);
 		}
 
 		if (source instanceof DBObject) {
 			return getMappedObject((DBObject) source, entity);
 		}
 
+		return delegateConvertToMongoType(source, entity);
+	}
+
+	/**
+	 * Converts the given source Object to a mongo type with the type information of the original source type omitted.
+	 * Subclasses may overwrite this method to retain the type information of the source type on the resulting mongo type.
+	 * 
+	 * @param source
+	 * @param entity
+	 * @return the converted mongo type or null if source is null
+	 */
+	protected Object delegateConvertToMongoType(Object source, MongoPersistentEntity<?> entity) {
 		return converter.convertToMongoType(source);
 	}
 
 	/**
-	 * Converts the given source assuming it's actually an association to anoter object.
+	 * Converts the given source assuming it's actually an association to another object.
 	 * 
 	 * @param source
 	 * @param property
@@ -243,7 +287,40 @@ public class QueryMapper {
 			// Ignore
 		}
 
-		return converter.convertToMongoType(id);
+		return delegateConvertToMongoType(id, null);
+	}
+
+	/**
+	 * Returns whether the given {@link Object} is a keyword, i.e. if it's a {@link DBObject} with a keyword key.
+	 * 
+	 * @param candidate
+	 * @return
+	 */
+	protected boolean isNestedKeyword(Object candidate) {
+
+		if (!(candidate instanceof BasicDBObject)) {
+			return false;
+		}
+
+		BasicDBObject dbObject = (BasicDBObject) candidate;
+		Set<String> keys = dbObject.keySet();
+
+		if (keys.size() != 1) {
+			return false;
+		}
+
+		return isKeyword(keys.iterator().next().toString());
+	}
+
+	/**
+	 * Returns whether the given {@link String} is a MongoDB keyword. The default implementation will check against the
+	 * set of registered keywords returned by {@link #getKeywords()}.
+	 * 
+	 * @param candidate
+	 * @return
+	 */
+	protected boolean isKeyword(String candidate) {
+		return candidate.startsWith("$");
 	}
 
 	/**
@@ -253,36 +330,49 @@ public class QueryMapper {
 	 */
 	private static class Keyword {
 
-		String key;
-		Object value;
+		private static final String N_OR_PATTERN = "\\$.*or";
 
-		Keyword(Object source) {
+		private final String key;
+		private final Object value;
 
-			Assert.isInstanceOf(DBObject.class, source);
+		public Keyword(DBObject source, String key) {
+			this.key = key;
+			this.value = source.get(key);
+		}
 
-			DBObject value = (DBObject) source;
+		public Keyword(DBObject dbObject) {
 
-			Assert.isTrue(value.keySet().size() == 1, "Keyword must have a single key only!");
+			Set<String> keys = dbObject.keySet();
+			Assert.isTrue(keys.size() == 1, "Can only use a single value DBObject!");
 
-			this.key = value.keySet().iterator().next();
-			this.value = value.get(key);
+			this.key = keys.iterator().next();
+			this.value = dbObject.get(key);
 		}
 
 		/**
-		 * Returns whether the given value actually represents a keyword. If this returns {@literal true} it's safe to call
-		 * the constructor.
+		 * Returns whether the current keyword is the {@code $exists} keyword.
 		 * 
-		 * @param value
 		 * @return
 		 */
-		static boolean isKeyword(Object value) {
+		public boolean isExists() {
+			return "$exists".equalsIgnoreCase(key);
+		}
 
-			if (!(value instanceof DBObject)) {
-				return false;
-			}
+		public boolean isOrOrNor() {
+			return key.matches(N_OR_PATTERN);
+		}
 
-			DBObject dbObject = (DBObject) value;
-			return dbObject.keySet().size() == 1 && dbObject.keySet().iterator().next().startsWith("$");
+		public boolean hasIterableValue() {
+			return value instanceof Iterable;
+		}
+
+		public String getKey() {
+			return key;
+		}
+
+		@SuppressWarnings("unchecked")
+		public <T> T getValue() {
+			return (T) value;
 		}
 	}
 
@@ -298,7 +388,7 @@ public class QueryMapper {
 		protected final String name;
 
 		/**
-		 * Creates a new {@link Field} without meta-information but the given name.
+		 * Creates a new {@link DocumentField} without meta-information but the given name.
 		 * 
 		 * @param name must not be {@literal null} or empty.
 		 */
@@ -309,7 +399,7 @@ public class QueryMapper {
 		}
 
 		/**
-		 * Returns a new {@link Field} with the given name.
+		 * Returns a new {@link DocumentField} with the given name.
 		 * 
 		 * @param name must not be {@literal null} or empty.
 		 * @return
@@ -365,7 +455,7 @@ public class QueryMapper {
 	}
 
 	/**
-	 * Extension of {@link Field} to be backed with mapping metadata.
+	 * Extension of {@link DocumentField} to be backed with mapping metadata.
 	 * 
 	 * @author Oliver Gierke
 	 */

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

@@ -0,0 +1,52 @@
+/*
+ * 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.
+ * 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.convert;
+
+import org.springframework.data.mongodb.core.mapping.MongoPersistentEntity;
+
+/**
+ * A subclass of {@link QueryMapper} that retains type information on the mongo types.
+ * 
+ * @author Thomas Darimont
+ */
+public class UpdateMapper extends QueryMapper {
+
+	private final MongoWriter<?> converter;
+
+	/**
+	 * Creates a new {@link UpdateMapper} using the given {@link MongoConverter}.
+	 * 
+	 * @param converter must not be {@literal null}.
+	 */
+	public UpdateMapper(MongoConverter converter) {
+
+		super(converter);
+		this.converter = converter;
+	}
+
+	/**
+	 * Converts the given source object to a mongo type retaining the original type information of the source type on the
+	 * mongo type.
+	 * 
+	 * @see org.springframework.data.mongodb.core.convert.QueryMapper#delegateConvertToMongoType(java.lang.Object,
+	 *      org.springframework.data.mongodb.core.mapping.MongoPersistentEntity)
+	 */
+	@Override
+	protected Object delegateConvertToMongoType(Object source, MongoPersistentEntity<?> entity) {
+		return entity == null ? super.delegateConvertToMongoType(source, null) : converter.convertToMongoType(source,
+				entity.getTypeInformation());
+	}
+}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/convert/package-info.java

@@ -0,0 +1,5 @@
+/**
+ * Spring Data MongoDB specific converter infrastructure.
+ */
+package org.springframework.data.mongodb.core.convert;
+

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

@@ -131,7 +131,7 @@ public class GeoResults<T> implements Iterable<GeoResult<T>> {
 	private static Distance calculateAverageDistance(List<? extends GeoResult<?>> results, Metric metric) {
 
 		if (results.isEmpty()) {
-			return new Distance(0, null);
+			return new Distance(0, metric);
 		}
 
 		double averageDistance = 0;

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/geo/package-info.java

@@ -0,0 +1,5 @@
+/**
+ * Support for MongoDB geo-spatial queries.
+ */
+package org.springframework.data.mongodb.core.geo;
+

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

@@ -27,6 +27,7 @@ import java.lang.annotation.Target;
  * @author Jon Brisbin
  * @author Oliver Gierke
  * @author Philipp Schneider
+ * @author Johno Crawford
  */
 @Target({ ElementType.TYPE })
 @Documented
@@ -78,4 +79,12 @@ public @interface CompoundIndex {
 	 * @return
 	 */
 	boolean background() default false;
+
+	/**
+	 * Configures the number of seconds after which the collection should expire. Defaults to -1 for no expiry.
+	 * 
+	 * @see http://docs.mongodb.org/manual/tutorial/expire-data/
+	 * @return
+	 */
+	int expireAfterSeconds() default -1;
 }

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

@@ -26,6 +26,7 @@ import java.lang.annotation.Target;
  * @author Jon Brisbin
  * @author Oliver Gierke
  * @author Philipp Schneider
+ * @author Johno Crawford
  */
 @Target(ElementType.FIELD)
 @Retention(RetentionPolicy.RUNTIME)
@@ -50,4 +51,12 @@ public @interface Indexed {
 	 * @return
 	 */
 	boolean background() default false;
+
+	/**
+	 * Configures the number of seconds after which the collection should expire. Defaults to -1 for no expiry.
+	 * 
+	 * @see http://docs.mongodb.org/manual/tutorial/expire-data/
+	 * @return
+	 */
+	int expireAfterSeconds() default -1;
 }

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

@@ -44,6 +44,7 @@ import com.mongodb.util.JSON;
  * @author Jon Brisbin
  * @author Oliver Gierke
  * @author Philipp Schneider
+ * @author Johno Crawford
  */
 public class MongoPersistentEntityIndexCreator implements
 		ApplicationListener<MappingContextEvent<MongoPersistentEntity<?>, MongoPersistentProperty>> {
@@ -108,7 +109,7 @@ public class MongoPersistentEntityIndexCreator implements
 					DBObject definition = (DBObject) JSON.parse(index.def());
 
 					ensureIndex(indexColl, index.name(), definition, index.unique(), index.dropDups(), index.sparse(),
-							index.background());
+							index.background(), index.expireAfterSeconds());
 
 					if (log.isDebugEnabled()) {
 						log.debug("Created compound index " + index);
@@ -143,7 +144,7 @@ public class MongoPersistentEntityIndexCreator implements
 						DBObject definition = new BasicDBObject(persistentProperty.getFieldName(), direction);
 
 						ensureIndex(collection, name, definition, index.unique(), index.dropDups(), index.sparse(),
-								index.background());
+								index.background(), index.expireAfterSeconds());
 
 						if (log.isDebugEnabled()) {
 							log.debug("Created property index " + index);
@@ -192,9 +193,11 @@ public class MongoPersistentEntityIndexCreator implements
 	 * @param unique whether it shall be a unique index
 	 * @param dropDups whether to drop duplicates
 	 * @param sparse sparse or not
+	 * @param background whether the index will be created in the background
+	 * @param expireAfterSeconds the time to live for documents in the collection
 	 */
 	protected void ensureIndex(String collection, String name, DBObject indexDefinition, boolean unique,
-			boolean dropDups, boolean sparse, boolean background) {
+			boolean dropDups, boolean sparse, boolean background, int expireAfterSeconds) {
 
 		DBObject opts = new BasicDBObject();
 		opts.put("name", name);
@@ -203,6 +206,10 @@ public class MongoPersistentEntityIndexCreator implements
 		opts.put("unique", unique);
 		opts.put("background", background);
 
+		if (expireAfterSeconds != -1) {
+			opts.put("expireAfterSeconds", expireAfterSeconds);
+		}
+
 		mongoDbFactory.getDb().getCollection(collection).ensureIndex(indexDefinition, opts);
 	}
 }

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/index/package-info.java

@@ -0,0 +1,5 @@
+/**
+ * Support for MongoDB document indexing.
+ */
+package org.springframework.data.mongodb.core.index;
+

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

@@ -15,6 +15,7 @@
  */
 package org.springframework.data.mongodb.core.mapping;
 
+import java.lang.reflect.Field;
 import java.util.Comparator;
 import java.util.HashMap;
 import java.util.Map;
@@ -24,6 +25,7 @@ import org.springframework.context.ApplicationContext;
 import org.springframework.context.ApplicationContextAware;
 import org.springframework.context.expression.BeanFactoryAccessor;
 import org.springframework.context.expression.BeanFactoryResolver;
+import org.springframework.data.annotation.Id;
 import org.springframework.data.mapping.Association;
 import org.springframework.data.mapping.AssociationHandler;
 import org.springframework.data.mapping.PropertyHandler;
@@ -35,6 +37,7 @@ import org.springframework.expression.Expression;
 import org.springframework.expression.ParserContext;
 import org.springframework.expression.spel.standard.SpelExpressionParser;
 import org.springframework.expression.spel.support.StandardEvaluationContext;
+import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
 
 /**
@@ -43,11 +46,12 @@ import org.springframework.util.StringUtils;
  * 
  * @author Jon Brisbin
  * @author Oliver Gierke
+ * @author Thomas Darimont
  */
 public class BasicMongoPersistentEntity<T> extends BasicPersistentEntity<T, MongoPersistentProperty> implements
 		MongoPersistentEntity<T>, ApplicationContextAware {
 
-	private static final String AMBIGUOUS_FIELD_MAPPING = "Ambiguous field mapping detected! Both %s and %s map to the same field name %s! Disambiguate using @Field annotation!";
+	private static final String AMBIGUOUS_FIELD_MAPPING = "Ambiguous field mapping detected! Both %s and %s map to the same field name %s! Disambiguate using @DocumentField annotation!";
 	private final String collection;
 	private final SpelExpressionParser parser;
 	private final StandardEvaluationContext context;
@@ -136,6 +140,60 @@ public class BasicMongoPersistentEntity<T> extends BasicPersistentEntity<T, Mong
 		}
 	}
 
+	/**
+	 * As a general note: An implicit id property has a name that matches "id" or "_id". An explicit id property is one
+	 * that is annotated with @see {@link Id}. The property id is updated according to the following rules: 1) An id
+	 * property which is defined explicitly takes precedence over an implicitly defined id property. 2) In case of any
+	 * ambiguity a @see {@link MappingException} is thrown.
+	 * 
+	 * @param property - the new id property candidate
+	 * @return
+	 */
+	@Override
+	protected MongoPersistentProperty returnPropertyIfBetterIdPropertyCandidateOrNull(MongoPersistentProperty property) {
+
+		Assert.notNull(property);
+
+		if (!property.isIdProperty()) {
+			return null;
+		}
+
+		MongoPersistentProperty currentIdProperty = getIdProperty();
+
+		boolean currentIdPropertyIsSet = currentIdProperty != null;
+		@SuppressWarnings("null")
+		boolean currentIdPropertyIsExplicit = currentIdPropertyIsSet ? currentIdProperty.isExplicitIdProperty() : false;
+		boolean newIdPropertyIsExplicit = property.isExplicitIdProperty();
+
+		if (!currentIdPropertyIsSet) {
+			return property;
+
+		}
+
+		@SuppressWarnings("null")
+		Field currentIdPropertyField = currentIdProperty.getField();
+
+		if (newIdPropertyIsExplicit && currentIdPropertyIsExplicit) {
+			throw new MappingException(String.format(
+					"Attempt to add explicit id property %s but already have an property %s registered "
+							+ "as explicit id. Check your mapping configuration!", property.getField(), currentIdPropertyField));
+
+		} else if (newIdPropertyIsExplicit && !currentIdPropertyIsExplicit) {
+			// explicit id property takes precedence over implicit id property
+			return property;
+
+		} else if (!newIdPropertyIsExplicit && currentIdPropertyIsExplicit) {
+			// no id property override - current property is explicitly defined
+
+		} else {
+			throw new MappingException(String.format(
+					"Attempt to add id property %s but already have an property %s registered "
+							+ "as id. Check your mapping configuration!", property.getField(), currentIdPropertyField));
+		}
+
+		return null;
+	}
+
 	/**
 	 * Handler to collect {@link MongoPersistentProperty} instances and check that each of them is mapped to a distinct
 	 * field name.

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

@@ -24,6 +24,7 @@ import java.util.Set;
 import org.bson.types.ObjectId;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
+import org.springframework.data.annotation.Id;
 import org.springframework.data.mapping.Association;
 import org.springframework.data.mapping.model.AnnotationBasedPersistentProperty;
 import org.springframework.data.mapping.model.MappingException;
@@ -38,6 +39,7 @@ import com.mongodb.DBObject;
  * 
  * @author Oliver Gierke
  * @author Patryk Wasik
+ * @author Thomas Darimont
  */
 public class BasicMongoPersistentProperty extends AnnotationBasedPersistentProperty<MongoPersistentProperty> implements
 		MongoPersistentProperty {
@@ -109,6 +111,15 @@ public class BasicMongoPersistentProperty extends AnnotationBasedPersistentPrope
 		return SUPPORTED_ID_PROPERTY_NAMES.contains(field.getName());
 	}
 
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.mapping.MongoPersistentProperty#isExplicitIdProperty()
+	 */
+	@Override
+	public boolean isExplicitIdProperty() {
+		return isAnnotationPresent(Id.class);
+	}
+
 	/**
 	 * Returns the key to be used to store the value of the property inside a Mongo {@link DBObject}.
 	 * 
@@ -117,7 +128,18 @@ public class BasicMongoPersistentProperty extends AnnotationBasedPersistentPrope
 	public String getFieldName() {
 
 		if (isIdProperty()) {
-			return ID_FIELD_NAME;
+
+			if (owner == null) {
+				return ID_FIELD_NAME;
+			}
+
+			if (owner.getIdProperty() == null) {
+				return ID_FIELD_NAME;
+			}
+
+			if (owner.isIdProperty(this)) {
+				return ID_FIELD_NAME;
+			}
 		}
 
 		org.springframework.data.mongodb.core.mapping.Field annotation = findAnnotation(org.springframework.data.mongodb.core.mapping.Field.class);

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2011-2012 by the original author(s).
+ * Copyright 2011-2013 by the original author(s).
  *
  * 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 org.springframework.data.annotation.Reference;
  * An annotation that indicates the annotated field is to be stored using a {@link com.mongodb.DBRef}.
  * 
  * @author Jon Brisbin
- * @authot Oliver Gierke
+ * @author Oliver Gierke
+ * @author Thomas Darimont
  */
 @Documented
 @Retention(RetentionPolicy.RUNTIME)
@@ -41,4 +42,11 @@ public @interface DBRef {
 	 * @return
 	 */
 	String db() default "";
+
+	/**
+	 * Controls whether the referenced entity should be loaded lazily. This defaults to {@literal false}.
+	 * 
+	 * @return
+	 */
+	boolean lazy() default false;
 }

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

@@ -18,7 +18,7 @@ package org.springframework.data.mongodb.core.mapping;
 /**
  * SPI interface to determine how to name document fields in cases the field name is not manually defined.
  * 
- * @see Field
+ * @see DocumentField
  * @see PropertyNameFieldNamingStrategy
  * @see CamelCaseAbbreviatingFieldNamingStrategy
  * @since 1.3

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2011-2012 the original author or authors.
+ * Copyright 2011-2013 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.
@@ -16,6 +16,8 @@
 package org.springframework.data.mongodb.core.mapping;
 
 import org.springframework.core.convert.converter.Converter;
+import org.springframework.data.annotation.Id;
+import org.springframework.data.mapping.PersistentEntity;
 import org.springframework.data.mapping.PersistentProperty;
 
 /**
@@ -23,6 +25,7 @@ import org.springframework.data.mapping.PersistentProperty;
  * 
  * @author Oliver Gierke
  * @author Patryk Wasik
+ * @author Thomas Darimont
  */
 public interface MongoPersistentProperty extends PersistentProperty<MongoPersistentProperty> {
 
@@ -48,6 +51,14 @@ public interface MongoPersistentProperty extends PersistentProperty<MongoPersist
 	 */
 	boolean isDbReference();
 
+	/**
+	 * Returns whether the property is explicitly marked as an identifier property of the owning {@link PersistentEntity}.
+	 * A property is an explicit id property if it is annotated with @see {@link Id}.
+	 * 
+	 * @return
+	 */
+	boolean isExplicitIdProperty();
+
 	/**
 	 * Returns the {@link DBRef} if the property is a reference.
 	 * 

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/mapping/event/package-info.java

@@ -0,0 +1,5 @@
+/**
+ * Mapping event callback infrastructure for the MongoDB document-to-object mapping subsystem.
+ */
+package org.springframework.data.mongodb.core.mapping.event;
+

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/mapping/package-info.java

@@ -0,0 +1,5 @@
+/**
+ * Infrastructure for the MongoDB document-to-object mapping subsystem.
+ */
+package org.springframework.data.mongodb.core.mapping;
+

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/mapreduce/package-info.java

@@ -0,0 +1,5 @@
+/**
+ * Support for MongoDB map-reduce operations.
+ */
+package org.springframework.data.mongodb.core.mapreduce;
+

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2011 the original author or authors.
+ * Copyright 2010-2013 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.
@@ -39,6 +39,10 @@ import com.mongodb.DBObject;
 /**
  * Central class for creating queries. It follows a fluent API style so that you can easily chain together multiple
  * criteria. Static import of the 'Criteria.where' method will improve readability.
+ * 
+ * @author Thomas Risberg
+ * @author Oliver Gierke
+ * @author Thomas Darimont
  */
 public class Criteria implements CriteriaDefinition {
 
@@ -396,34 +400,54 @@ public class Criteria implements CriteriaDefinition {
 
 	/**
 	 * Creates an 'or' criteria using the $or operator for all of the provided criteria
+	 * <p>
+	 * Note that mongodb doesn't support an $or operator to be wrapped in a $not operator.
+	 * <p>
 	 * 
+	 * @throws IllegalArgumentException if {@link #orOperator(Criteria...)} follows a not() call directly.
 	 * @param criteria
 	 */
 	public Criteria orOperator(Criteria... criteria) {
 		BasicDBList bsonList = createCriteriaList(criteria);
-		criteriaChain.add(new Criteria("$or").is(bsonList));
-		return this;
+		return registerCriteriaChainElement(new Criteria("$or").is(bsonList));
 	}
 
 	/**
-	 * Creates a 'nor' criteria using the $nor operator for all of the provided criteria
+	 * Creates a 'nor' criteria using the $nor operator for all of the provided criteria.
+	 * <p>
+	 * Note that mongodb doesn't support an $nor operator to be wrapped in a $not operator.
+	 * <p>
 	 * 
+	 * @throws IllegalArgumentException if {@link #norOperator(Criteria...)} follows a not() call directly.
 	 * @param criteria
 	 */
 	public Criteria norOperator(Criteria... criteria) {
 		BasicDBList bsonList = createCriteriaList(criteria);
-		criteriaChain.add(new Criteria("$nor").is(bsonList));
-		return this;
+		return registerCriteriaChainElement(new Criteria("$nor").is(bsonList));
 	}
 
 	/**
-	 * Creates an 'and' criteria using the $and operator for all of the provided criteria
+	 * Creates an 'and' criteria using the $and operator for all of the provided criteria.
+	 * <p>
+	 * Note that mongodb doesn't support an $and operator to be wrapped in a $not operator.
+	 * <p>
 	 * 
+	 * @throws IllegalArgumentException if {@link #andOperator(Criteria...)} follows a not() call directly.
 	 * @param criteria
 	 */
 	public Criteria andOperator(Criteria... criteria) {
 		BasicDBList bsonList = createCriteriaList(criteria);
-		criteriaChain.add(new Criteria("$and").is(bsonList));
+		return registerCriteriaChainElement(new Criteria("$and").is(bsonList));
+	}
+
+	private Criteria registerCriteriaChainElement(Criteria criteria) {
+
+		if (lastOperatorWasNot()) {
+			throw new IllegalArgumentException("operator $not is not allowed around criteria chain element: "
+					+ criteria.getCriteriaObject());
+		} else {
+			criteriaChain.add(criteria);
+		}
 		return this;
 	}
 
@@ -468,6 +492,7 @@ public class Criteria implements CriteriaDefinition {
 				}
 			}
 		}
+
 		DBObject queryCriteria = new BasicDBObject();
 		if (isValue != NOT_SET) {
 			queryCriteria.put(this.key, this.isValue);

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

@@ -73,7 +73,7 @@ public class Field {
 	 */
 	public Field position(String field, int value) {
 
-		Assert.hasText(field, "Field must not be null or empty!");
+		Assert.hasText(field, "DocumentField must not be null or empty!");
 
 		postionKey = field;
 		positionValue = value;

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

@@ -15,6 +15,7 @@
  */
 package org.springframework.data.mongodb.core.query;
 
+import org.springframework.data.domain.Pageable;
 import org.springframework.data.mongodb.core.geo.CustomMetric;
 import org.springframework.data.mongodb.core.geo.Distance;
 import org.springframework.data.mongodb.core.geo.Metric;
@@ -29,6 +30,7 @@ import com.mongodb.DBObject;
  * Builder class to build near-queries.
  * 
  * @author Oliver Gierke
+ * @author Thomas Darimont
  */
 public class NearQuery {
 
@@ -38,6 +40,7 @@ public class NearQuery {
 	private Metric metric;
 	private boolean spherical;
 	private Integer num;
+	private Integer skip;
 
 	/**
 	 * Creates a new {@link NearQuery}.
@@ -116,7 +119,7 @@ public class NearQuery {
 	}
 
 	/**
-	 * Configures the number of results to return.
+	 * Configures the maximum number of results to return.
 	 * 
 	 * @param num
 	 * @return
@@ -126,6 +129,29 @@ public class NearQuery {
 		return this;
 	}
 
+	/**
+	 * Configures the number of results to skip.
+	 * 
+	 * @param skip
+	 * @return
+	 */
+	public NearQuery skip(int skip) {
+		this.skip = skip;
+		return this;
+	}
+
+	/**
+	 * Configures the {@link Pageable} to use.
+	 * 
+	 * @param pageable
+	 * @return
+	 */
+	public NearQuery with(Pageable pageable) {
+		this.num = pageable.getOffset() + pageable.getPageSize();
+		this.skip = pageable.getOffset();
+		return this;
+	}
+
 	/**
 	 * Sets the max distance results shall have from the configured origin. If a {@link Metric} was set before the given
 	 * value will be interpreted as being a value in that metric. E.g.
@@ -290,9 +316,18 @@ public class NearQuery {
 	 */
 	public NearQuery query(Query query) {
 		this.query = query;
+		this.skip = query.getSkip();
+		this.num = query.getLimit();
 		return this;
 	}
 
+	/**
+	 * @return the number of elements to skip.
+	 */
+	public Integer getSkip() {
+		return skip;
+	}
+
 	/**
 	 * Returns the {@link DBObject} built by the {@link NearQuery}.
 	 * 

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

@@ -19,8 +19,11 @@ import static org.springframework.data.mongodb.core.query.SerializationUtils.*;
 import static org.springframework.util.ObjectUtils.*;
 
 import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashSet;
 import java.util.LinkedHashMap;
 import java.util.List;
+import java.util.Set;
 
 import org.springframework.data.domain.Pageable;
 import org.springframework.data.domain.Sort;
@@ -34,9 +37,13 @@ import com.mongodb.DBObject;
 /**
  * @author Thomas Risberg
  * @author Oliver Gierke
+ * @author Thomas Darimont
  */
 public class Query {
 
+	private final static String RESTRICTED_TYPES_KEY = "_$RESTRICTED_TYPES";
+
+	private final Set<Class<?>> restrictedTypes = new HashSet<Class<?>>();
 	private LinkedHashMap<String, Criteria> criteria = new LinkedHashMap<String, Criteria>();
 	private Field fieldSpec;
 	private Sort sort;
@@ -54,8 +61,7 @@ public class Query {
 		return new Query(criteria);
 	}
 
-	public Query() {
-	}
+	public Query() {}
 
 	/**
 	 * Creates a new {@link Query} using the given {@link Criteria}.
@@ -161,13 +167,46 @@ public class Query {
 		return this;
 	}
 
+	/**
+	 * @return the restrictedTypes
+	 */
+	public Set<Class<?>> getRestrictedTypes() {
+		return restrictedTypes == null ? Collections.<Class<?>> emptySet() : restrictedTypes;
+	}
+
+	/**
+	 * Restricts the query to only return documents instances that are exactly of the given types.
+	 * 
+	 * @param type may not be {@literal null}
+	 * @param additionalTypes may not be {@literal null}
+	 * @return
+	 */
+	public Query restrict(Class<?> type, Class<?>... additionalTypes) {
+
+		Assert.notNull(type, "Type must not be null!");
+		Assert.notNull(additionalTypes, "AdditionalTypes must not be null");
+
+		restrictedTypes.add(type);
+		for (Class<?> additionalType : additionalTypes) {
+			restrictedTypes.add(additionalType);
+		}
+
+		return this;
+	}
+
 	public DBObject getQueryObject() {
+
 		DBObject dbo = new BasicDBObject();
 		for (String k : criteria.keySet()) {
 			CriteriaDefinition c = criteria.get(k);
 			DBObject cl = c.getCriteriaObject();
 			dbo.putAll(cl);
 		}
+
+		if (!restrictedTypes.isEmpty()) {
+			dbo.put(RESTRICTED_TYPES_KEY, getRestrictedTypes());
+		}
+
 		return dbo;
 	}
 
@@ -266,4 +305,17 @@ public class Query {
 
 		return result;
 	}
+
+	/**
+	 * Returns whether the given key is the one used to hold the type restriction information.
+	 * 
+	 * @deprecated don't call this method as the restricted type handling will undergo some significant changes going
+	 *             forward.
+	 * @param key
+	 * @return
+	 */
+	@Deprecated
+	public static boolean isRestrictedTypeKey(String key) {
+		return RESTRICTED_TYPES_KEY.equals(key);
+	}
 }

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

@@ -31,6 +31,7 @@ import com.mongodb.DBObject;
  * @author Thomas Risberg
  * @author Mark Pollack
  * @author Oliver Gierke
+ * @author Becca Gaspard
  */
 public class Update {
 
@@ -90,6 +91,18 @@ public class Update {
 		return this;
 	}
 
+	/**
+	 * Update using the $setOnInsert update modifier
+	 * 
+	 * @param key
+	 * @param value
+	 * @return
+	 */
+	public Update setOnInsert(String key, Object value) {
+		addMultiFieldOperation("$setOnInsert", key, value);
+		return this;
+	}
+
 	/**
 	 * Update using the $unset update modifier
 	 * 
@@ -217,22 +230,23 @@ public class Update {
 		return dbo;
 	}
 
-	@SuppressWarnings("unchecked")
 	protected void addMultiFieldOperation(String operator, String key, Object value) {
+
 		Object existingValue = this.modifierOps.get(operator);
-		LinkedHashMap<String, Object> keyValueMap;
+		DBObject keyValueMap;
+
 		if (existingValue == null) {
-			keyValueMap = new LinkedHashMap<String, Object>();
+			keyValueMap = new BasicDBObject();
 			this.modifierOps.put(operator, keyValueMap);
 		} else {
-			if (existingValue instanceof LinkedHashMap) {
-				keyValueMap = (LinkedHashMap<String, Object>) existingValue;
+			if (existingValue instanceof BasicDBObject) {
+				keyValueMap = (BasicDBObject) existingValue;
 			} else {
 				throw new InvalidDataAccessApiUsageException("Modifier Operations should be a LinkedHashMap but was "
 						+ existingValue.getClass());
 			}
 		}
+
 		keyValueMap.put(key, value);
 	}
-
 }

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

@@ -0,0 +1,217 @@
+/*
+ * 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.
+ * 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.spel;
+
+import java.util.Collections;
+import java.util.Iterator;
+
+import org.springframework.expression.spel.ExpressionState;
+import org.springframework.expression.spel.SpelNode;
+import org.springframework.expression.spel.ast.Literal;
+import org.springframework.expression.spel.ast.MethodReference;
+import org.springframework.expression.spel.ast.Operator;
+import org.springframework.util.Assert;
+
+/**
+ * A value object for nodes in an expression. Allows iterating ove potentially available child {@link ExpressionNode}s.
+ * 
+ * @author Oliver Gierke
+ */
+public class ExpressionNode implements Iterable<ExpressionNode> {
+
+	private static final Iterator<ExpressionNode> EMPTY_ITERATOR = Collections.<ExpressionNode> emptySet().iterator();
+
+	private final SpelNode node;
+	private final ExpressionState state;
+
+	/**
+	 * Creates a new {@link ExpressionNode} from the given {@link SpelNode} and {@link ExpressionState}.
+	 * 
+	 * @param node must not be {@literal null}.
+	 * @param state must not be {@literal null}.
+	 */
+	protected ExpressionNode(SpelNode node, ExpressionState state) {
+
+		Assert.notNull(node, "SpelNode must not be null!");
+		Assert.notNull(state, "ExpressionState must not be null!");
+
+		this.node = node;
+		this.state = state;
+	}
+
+	/**
+	 * Factory method to create {@link ExpressionNode}'s according to the given {@link SpelNode} and
+	 * {@link ExpressionState}.
+	 * 
+	 * @param node
+	 * @param state must not be {@literal null}.
+	 * @return an {@link ExpressionNode} for the given {@link SpelNode} or {@literal null} if {@literal null} was given
+	 *         for the {@link SpelNode}.
+	 */
+	public static ExpressionNode from(SpelNode node, ExpressionState state) {
+
+		if (node == null) {
+			return null;
+		}
+
+		if (node instanceof Operator) {
+			return new OperatorNode((Operator) node, state);
+		}
+
+		if (node instanceof MethodReference) {
+			return new MethodReferenceNode((MethodReference) node, state);
+		}
+
+		if (node instanceof Literal) {
+			return new LiteralNode((Literal) node, state);
+		}
+
+		return new ExpressionNode(node, state);
+	}
+
+	/**
+	 * Returns the name of the {@link ExpressionNode}.
+	 * 
+	 * @return
+	 */
+	public String getName() {
+		return node.toStringAST();
+	}
+
+	/**
+	 * Returns whether the current {@link ExpressionNode} is backed by the given type.
+	 * 
+	 * @param type must not be {@literal null}.
+	 * @return
+	 */
+	public boolean isOfType(Class<?> type) {
+
+		Assert.notNull(type, "Type must not be empty!");
+		return type.isAssignableFrom(node.getClass());
+	}
+
+	/**
+	 * Returns whether the given {@link ExpressionNode} is representing the same backing node type as the current one.
+	 * 
+	 * @param node
+	 * @return
+	 */
+	boolean isOfSameTypeAs(ExpressionNode node) {
+		return node == null ? false : this.node.getClass().equals(node.node.getClass());
+	}
+
+	/**
+	 * Returns whether the {@link ExpressionNode} is a mathematical operation.
+	 * 
+	 * @return
+	 */
+	public boolean isMathematicalOperation() {
+		return false;
+	}
+
+	/**
+	 * Returns whether the {@link ExpressionNode} is a literal.
+	 * 
+	 * @return
+	 */
+	public boolean isLiteral() {
+		return false;
+	}
+
+	/**
+	 * Returns the value of the current node.
+	 * 
+	 * @return
+	 */
+	public Object getValue() {
+		return node.getValue(state);
+	}
+
+	/**
+	 * Returns whether the current node has child nodes.
+	 * 
+	 * @return
+	 */
+	public boolean hasChildren() {
+		return node.getChildCount() != 0;
+	}
+
+	/**
+	 * Returns the child {@link ExpressionNode} with the given index.
+	 * 
+	 * @param index must not be negative.
+	 * @return
+	 */
+	public ExpressionNode getChild(int index) {
+
+		Assert.isTrue(index >= 0);
+		return from(node.getChild(index), state);
+	}
+
+	/**
+	 * Returns whether the {@link ExpressionNode} has a first child node that is not of the given type.
+	 * 
+	 * @param type must not be {@literal null}.
+	 * @return
+	 */
+	public boolean hasfirstChildNotOfType(Class<?> type) {
+
+		Assert.notNull(type, "Type must not be null!");
+		return hasChildren() && !node.getChild(0).getClass().equals(type);
+	}
+
+	/**
+	 * Creates a new {@link ExpressionNode} from the given {@link SpelNode}.
+	 * 
+	 * @param node
+	 * @return
+	 */
+	protected ExpressionNode from(SpelNode node) {
+		return from(node, state);
+	}
+
+	/* 
+	 * (non-Javadoc)
+	 * @see java.lang.Iterable#iterator()
+	 */
+	@Override
+	public Iterator<ExpressionNode> iterator() {
+
+		if (!hasChildren()) {
+			return EMPTY_ITERATOR;
+		}
+
+		return new Iterator<ExpressionNode>() {
+
+			int index = 0;
+
+			@Override
+			public boolean hasNext() {
+				return index < node.getChildCount();
+			}
+
+			@Override
+			public ExpressionNode next() {
+				return from(node.getChild(index++));
+			}
+
+			@Override
+			public void remove() {
+				throw new UnsupportedOperationException();
+			}
+		};
+	}
+}

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

@@ -0,0 +1,126 @@
+/*
+ * 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.
+ * 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.spel;
+
+import org.springframework.util.Assert;
+
+import com.mongodb.BasicDBList;
+import com.mongodb.DBObject;
+
+/**
+ * The context for an {@link ExpressionNode} transformation.
+ * 
+ * @author Thomas Darimont
+ * @author Oliver Gierke
+ */
+public class ExpressionTransformationContextSupport<T extends ExpressionNode> {
+
+	private final T currentNode;
+	private final ExpressionNode parentNode;
+	private final DBObject previousOperationObject;
+
+	/**
+	 * Creates a new {@link ExpressionTransformationContextSupport} for the given {@link ExpressionNode}s and an optional
+	 * previous operation.
+	 * 
+	 * @param currentNode must not be {@literal null}.
+	 * @param parentNode
+	 * @param previousOperationObject
+	 */
+	public ExpressionTransformationContextSupport(T currentNode, ExpressionNode parentNode,
+			DBObject previousOperationObject) {
+
+		Assert.notNull(currentNode, "currentNode must not be null!");
+
+		this.currentNode = currentNode;
+		this.parentNode = parentNode;
+		this.previousOperationObject = previousOperationObject;
+	}
+
+	/**
+	 * Returns the current {@link ExpressionNode}.
+	 * 
+	 * @return
+	 */
+	public T getCurrentNode() {
+		return currentNode;
+	}
+
+	/**
+	 * Returns the parent {@link ExpressionNode} or {@literal null} if none available.
+	 * 
+	 * @return
+	 */
+	public ExpressionNode getParentNode() {
+		return parentNode;
+	}
+
+	/**
+	 * Returns the previously accumulated operaton object or {@literal null} if none available. Rather than manually
+	 * adding stuff to the object prefer using {@link #addToPreviousOrReturn(Object)} to transparently do if one is
+	 * present.
+	 * 
+	 * @see #hasPreviousOperation()
+	 * @see #addToPreviousOrReturn(Object)
+	 * @return
+	 */
+	public DBObject getPreviousOperationObject() {
+		return previousOperationObject;
+	}
+
+	/**
+	 * Returns whether a previous operation is present.
+	 * 
+	 * @return
+	 */
+	public boolean hasPreviousOperation() {
+		return getPreviousOperationObject() != null;
+	}
+
+	/**
+	 * Returns whether the parent node is of the same operation as the current node.
+	 * 
+	 * @return
+	 */
+	public boolean parentIsSameOperation() {
+		return parentNode == null ? false : currentNode.isOfSameTypeAs(parentNode);
+	}
+
+	/**
+	 * Adds the given value to the previous operation and returns it.
+	 * 
+	 * @param value
+	 * @return
+	 */
+	public DBObject addToPreviousOperation(Object value) {
+		extractArgumentListFrom(previousOperationObject).add(value);
+		return previousOperationObject;
+	}
+
+	/**
+	 * Adds the given value to the previous operation if one is present or returns the value to add as is.
+	 * 
+	 * @param value
+	 * @return
+	 */
+	public Object addToPreviousOrReturn(Object value) {
+		return hasPreviousOperation() ? addToPreviousOperation(value) : value;
+	}
+
+	private BasicDBList extractArgumentListFrom(DBObject context) {
+		return (BasicDBList) context.get(context.keySet().iterator().next());
+	}
+}

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

@@ -0,0 +1,33 @@
+/*
+ * 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.
+ * 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.spel;
+
+/**
+ * SPI interface to implement components that can transfrom an {@link ExpressionTransformationContextSupport} into an
+ * object.
+ * 
+ * @author Oliver Gierke
+ */
+public interface ExpressionTransformer<T extends ExpressionTransformationContextSupport<?>> {
+
+	/**
+	 * Transforms the given {@link ExpressionTransformationContextSupport} into an Object.
+	 * 
+	 * @param context will never be {@literal null}.
+	 * @return
+	 */
+	Object transform(T context);
+}

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

@@ -0,0 +1,72 @@
+/*
+ * 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.
+ * 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.spel;
+
+import org.springframework.expression.spel.ExpressionState;
+import org.springframework.expression.spel.ast.FloatLiteral;
+import org.springframework.expression.spel.ast.IntLiteral;
+import org.springframework.expression.spel.ast.Literal;
+import org.springframework.expression.spel.ast.LongLiteral;
+import org.springframework.expression.spel.ast.NullLiteral;
+import org.springframework.expression.spel.ast.RealLiteral;
+import org.springframework.expression.spel.ast.StringLiteral;
+
+/**
+ * A node representing a literal in an expression.
+ * 
+ * @author Oliver Gierke
+ */
+public class LiteralNode extends ExpressionNode {
+
+	private final Literal literal;
+
+	/**
+	 * Creates a new {@link LiteralNode} from the given {@link Literal} and {@link ExpressionState}.
+	 * 
+	 * @param node must not be {@literal null}.
+	 * @param state must not be {@literal null}.
+	 */
+	LiteralNode(Literal node, ExpressionState state) {
+		super(node, state);
+		this.literal = node;
+	}
+
+	/**
+	 * Returns whether the given {@link ExpressionNode} is a unary minus.
+	 * 
+	 * @param parent
+	 * @return
+	 */
+	public boolean isUnaryMinus(ExpressionNode parent) {
+
+		if (!(parent instanceof OperatorNode)) {
+			return false;
+		}
+
+		OperatorNode operator = (OperatorNode) parent;
+		return operator.isUnaryMinus() && operator.getRight() == null;
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.spel.ExpressionNode#isLiteral()
+	 */
+	@Override
+	public boolean isLiteral() {
+		return literal instanceof FloatLiteral || literal instanceof RealLiteral || literal instanceof IntLiteral
+				|| literal instanceof LongLiteral || literal instanceof StringLiteral || literal instanceof NullLiteral;
+	}
+}

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

@@ -0,0 +1,75 @@
+/*
+ * 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.
+ * 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.spel;
+
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+
+import org.springframework.expression.spel.ExpressionState;
+import org.springframework.expression.spel.ast.MethodReference;
+
+/**
+ * An {@link ExpressionNode} representing a method reference.
+ * 
+ * @author Oliver Gierke
+ * @author Thomas Darimont
+ */
+public class MethodReferenceNode extends ExpressionNode {
+
+	private static final Map<String, String> FUNCTIONS;
+
+	static {
+
+		Map<String, String> map = new HashMap<String, String>();
+
+		map.put("concat", "$concat"); // Concatenates two strings.
+		map.put("strcasecmp", "$strcasecmp"); // Compares two strings and returns an integer that reflects the comparison.
+		map.put("substr", "$substr"); // Takes a string and returns portion of that string.
+		map.put("toLower", "$toLower"); // Converts a string to lowercase.
+		map.put("toUpper", "$toUpper"); // Converts a string to uppercase.
+
+		map.put("dayOfYear", "$dayOfYear"); // Converts a date to a number between 1 and 366.
+		map.put("dayOfMonth", "$dayOfMonth"); // Converts a date to a number between 1 and 31.
+		map.put("dayOfWeek", "$dayOfWeek"); // Converts a date to a number between 1 and 7.
+		map.put("year", "$year"); // Converts a date to the full year.
+		map.put("month", "$month"); // Converts a date into a number between 1 and 12.
+		map.put("week", "$week"); // Converts a date into a number between 0 and 53
+		map.put("hour", "$hour"); // Converts a date into a number between 0 and 23.
+		map.put("minute", "$minute"); // Converts a date into a number between 0 and 59.
+		map.put("second", "$second"); // Converts a date into a number between 0 and 59. May be 60 to account for leap
+		// seconds.
+		map.put("millisecond", "$millisecond"); // Returns the millisecond portion of a date as an integer between 0 and
+
+		FUNCTIONS = Collections.unmodifiableMap(map);
+	}
+
+	MethodReferenceNode(MethodReference reference, ExpressionState state) {
+		super(reference, state);
+	}
+
+	/**
+	 * Returns the name of the method.
+	 * 
+	 * @return
+	 */
+	public String getMethodName() {
+
+		String name = getName();
+		String methodName = name.substring(0, name.indexOf('('));
+		return FUNCTIONS.get(methodName);
+	}
+}

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

@@ -0,0 +1,120 @@
+/*
+ * 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.
+ * 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.spel;
+
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+
+import org.springframework.expression.spel.ExpressionState;
+import org.springframework.expression.spel.ast.OpDivide;
+import org.springframework.expression.spel.ast.OpMinus;
+import org.springframework.expression.spel.ast.OpModulus;
+import org.springframework.expression.spel.ast.OpMultiply;
+import org.springframework.expression.spel.ast.OpPlus;
+import org.springframework.expression.spel.ast.Operator;
+
+/**
+ * An {@link ExpressionNode} representing an operator.
+ * 
+ * @author Oliver Gierke
+ * @author Thomas Darimont
+ */
+public class OperatorNode extends ExpressionNode {
+
+	private static final Map<String, String> OPERATORS;
+
+	static {
+
+		Map<String, String> map = new HashMap<String, String>(6);
+
+		map.put("+", "$add");
+		map.put("-", "$subtract");
+		map.put("*", "$multiply");
+		map.put("/", "$divide");
+		map.put("%", "$mod");
+
+		OPERATORS = Collections.unmodifiableMap(map);
+	}
+
+	private final Operator operator;
+
+	/**
+	 * Creates a new {@link OperatorNode} from the given {@link Operator} and {@link ExpressionState}.
+	 * 
+	 * @param node must not be {@literal null}.
+	 * @param state must not be {@literal null}.
+	 */
+	OperatorNode(Operator node, ExpressionState state) {
+		super(node, state);
+		this.operator = node;
+	}
+
+	/* 
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.spel.ExpressionNode#isMathematicalOperation()
+	 */
+	@Override
+	public boolean isMathematicalOperation() {
+		return operator instanceof OpMinus || operator instanceof OpPlus || operator instanceof OpMultiply
+				|| operator instanceof OpDivide || operator instanceof OpModulus;
+	}
+
+	/**
+	 * Returns whether the operator is unary.
+	 * 
+	 * @return
+	 */
+	public boolean isUnaryOperator() {
+		return operator.getRightOperand() == null;
+	}
+
+	/**
+	 * Returns the Mongo expression of the operator.
+	 * 
+	 * @return
+	 */
+	public String getMongoOperator() {
+		return OPERATORS.get(operator.getOperatorName());
+	}
+
+	/**
+	 * Returns whether the operator is a unary minus, e.g. -1.
+	 * 
+	 * @return
+	 */
+	public boolean isUnaryMinus() {
+		return isUnaryOperator() && operator instanceof OpMinus;
+	}
+
+	/**
+	 * Returns the left operand as {@link ExpressionNode}.
+	 * 
+	 * @return
+	 */
+	public ExpressionNode getLeft() {
+		return from(operator.getLeftOperand());
+	}
+
+	/**
+	 * Returns the right operand as {@link ExpressionNode}.
+	 * 
+	 * @return
+	 */
+	public ExpressionNode getRight() {
+		return from(operator.getRightOperand());
+	}
+}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/spel/package-info.java

@@ -0,0 +1,5 @@
+/**
+ * Support classes to transform SpEL expressions into MongoDB expressions.
+ * @since 1.4
+ */
+package org.springframework.data.mongodb.core.spel;

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/gridfs/GridFsTemplate.java

@@ -158,7 +158,15 @@ public class GridFsTemplate implements GridFsOperations, ResourcePatternResolver
 	 * @see org.springframework.data.mongodb.gridfs.GridFsOperations#find(com.mongodb.DBObject)
 	 */
 	public List<GridFSDBFile> find(Query query) {
-		return getGridFs().find(getMappedQuery(query));
+
+		if (query == null) {
+			return getGridFs().find((DBObject) null);
+		}
+
+		DBObject queryObject = getMappedQuery(query.getQueryObject());
+		DBObject sortObject = getMappedQuery(query.getSortObject());
+
+		return getGridFs().find(queryObject, sortObject);
 	}
 
 	/*
@@ -221,7 +229,11 @@ public class GridFsTemplate implements GridFsOperations, ResourcePatternResolver
 	}
 
 	private DBObject getMappedQuery(Query query) {
-		return query == null ? null : queryMapper.getMappedObject(query.getQueryObject(), null);
+		return query == null ? null : getMappedQuery(query.getQueryObject());
+	}
+
+	private DBObject getMappedQuery(DBObject query) {
+		return query == null ? null : queryMapper.getMappedObject(query, null);
 	}
 
 	private GridFS getGridFs() {

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/gridfs/package-info.java

@@ -0,0 +1,5 @@
+/**
+ * Support for MongoDB GridFS feature.
+ */
+package org.springframework.data.mongodb.gridfs;
+

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/monitor/ServerInfo.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2011 the original author or authors.
+ * Copyright 2012-2013 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.
@@ -15,19 +15,20 @@
  */
 package org.springframework.data.mongodb.monitor;
 
-import java.net.InetAddress;
 import java.net.UnknownHostException;
 
-import com.mongodb.Mongo;
 import org.springframework.jmx.export.annotation.ManagedMetric;
 import org.springframework.jmx.export.annotation.ManagedOperation;
 import org.springframework.jmx.export.annotation.ManagedResource;
 import org.springframework.jmx.support.MetricType;
 
+import com.mongodb.Mongo;
+
 /**
  * Expose basic server information via JMX
  * 
  * @author Mark Pollack
+ * @author Thomas Darimont
  */
 @ManagedResource(description = "Server Information")
 public class ServerInfo extends AbstractMonitor {
@@ -36,9 +37,20 @@ public class ServerInfo extends AbstractMonitor {
 		this.mongo = mongo;
 	}
 
+	/**
+	 * Returns the hostname of the used server reported by mongo.
+	 * 
+	 * @return the reported hostname can also be an IP address.
+	 * @throws UnknownHostException
+	 */
 	@ManagedOperation(description = "Server host name")
 	public String getHostName() throws UnknownHostException {
-		return InetAddress.getLocalHost().getHostName();
+
+		/* 
+		 * UnknownHostException is not necessary anymore, but clients could have
+		 * called this method in a try..catch(UnknownHostException) already
+		 */
+		return getServerStatus().getServerUsed().getHost();
 	}
 
 	@ManagedMetric(displayName = "Uptime Estimate")

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/package-info.java

@@ -0,0 +1,5 @@
+/**
+ * Spring Data's MongoDB abstraction.
+ */
+package org.springframework.data.mongodb;
+

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/repository/Query.java

@@ -21,15 +21,19 @@ import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
+import org.springframework.data.annotation.QueryAnnotation;
+
 /**
  * Annotation to declare finder queries directly on repository methods. Both attributes allow using a placeholder
  * notation of {@code ?0}, {@code ?1} and so on.
  * 
  * @author Oliver Gierke
+ * @author Thomas Darimont
  */
 @Retention(RetentionPolicy.RUNTIME)
 @Target(ElementType.METHOD)
 @Documented
+@QueryAnnotation
 public @interface Query {
 
 	/**

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/repository/cdi/package-info.java

@@ -0,0 +1,5 @@
+/**
+ * CDI support for MongoDB specific repository implementation.
+ */
+package org.springframework.data.mongodb.repository.cdi;
+

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

@@ -35,6 +35,7 @@ import org.springframework.data.repository.query.QueryLookupStrategy.Key;
  * {@link #basePackages()} or {@link #basePackageClasses()} it will trigger scanning of the package of annotated class.
  * 
  * @author Oliver Gierke
+ * @author Thomas Darimont
  */
 @Target(ElementType.TYPE)
 @Retention(RetentionPolicy.RUNTIME)
@@ -119,4 +120,10 @@ public @interface EnableMongoRepositories {
 	 * @return
 	 */
 	boolean createIndexesForQueryMethods() default false;
+
+	/**
+	 * Configures whether nested repository-interfaces (e.g. defined as inner classes) should be discovered by the
+	 * repositories infrastructure.
+	 */
+	boolean considerNestedRepositories() default false;
 }

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/repository/config/package-info.java

@@ -0,0 +1,5 @@
+/**
+ * Support infrastructure for the configuration of MongoDB specific repositories.
+ */
+package org.springframework.data.mongodb.repository.config;
+