Release version 4.2 M2 (2023.1.0).

See #4450

.mvn/wrapper/maven-wrapper.properties

@@ -1,2 +1,2 @@
-#Mon Jul 03 09:49:43 CEST 2023
-distributionUrl=https\://repo.maven.apache.org/maven2/org/apache/maven/apache-maven/3.9.3/apache-maven-3.9.3-bin.zip
+#Mon Aug 14 08:53:22 EDT 2023
+distributionUrl=https\://repo.maven.apache.org/maven2/org/apache/maven/apache-maven/3.9.4/apache-maven-3.9.4-bin.zip

ci/pipeline.properties

@@ -1,5 +1,5 @@
 # Java versions
-java.main.tag=17.0.7_7-jdk-focal
+java.main.tag=17.0.8_7-jdk-focal
 java.next.tag=20-jdk-jammy
 
 # Docker container images - standard
@@ -7,12 +7,12 @@ docker.java.main.image=harbor-repo.vmware.com/dockerhub-proxy-cache/library/ecli
 docker.java.next.image=harbor-repo.vmware.com/dockerhub-proxy-cache/library/eclipse-temurin:${java.next.tag}
 
 # Supported versions of MongoDB
-docker.mongodb.4.4.version=4.4.22
-docker.mongodb.5.0.version=5.0.18
-docker.mongodb.6.0.version=6.0.7
+docker.mongodb.4.4.version=4.4.23
+docker.mongodb.5.0.version=5.0.19
+docker.mongodb.6.0.version=6.0.8
 
 # Supported versions of Redis
-docker.redis.6.version=6.2.12
+docker.redis.6.version=6.2.13
 
 # Supported versions of Cassandra
 docker.cassandra.3.version=3.11.15

pom.xml

@@ -5,7 +5,7 @@
 
 	<groupId>org.springframework.data</groupId>
 	<artifactId>spring-data-mongodb-parent</artifactId>
-	<version>4.2.0-SNAPSHOT</version>
+	<version>4.2.0-M2</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>3.2.0-SNAPSHOT</version>
+		<version>3.2.0-M2</version>
 	</parent>
 
 	<modules>
@@ -26,7 +26,7 @@
 	<properties>
 		<project.type>multi</project.type>
 		<dist.id>spring-data-mongodb</dist.id>
-		<springdata.commons>3.2.0-SNAPSHOT</springdata.commons>
+		<springdata.commons>3.2.0-M2</springdata.commons>
 		<mongo>4.10.2</mongo>
 		<mongo.reactivestreams>${mongo}</mongo.reactivestreams>
 		<jmh.version>1.19</jmh.version>
@@ -144,16 +144,6 @@
 	</dependencies>
 
 	<repositories>
-		<repository>
-			<id>spring-snapshot</id>
-			<url>https://repo.spring.io/snapshot</url>
-			<snapshots>
-				<enabled>true</enabled>
-			</snapshots>
-			<releases>
-				<enabled>false</enabled>
-			</releases>
-		</repository>
 		<repository>
 			<id>spring-milestone</id>
 			<url>https://repo.spring.io/milestone</url>

spring-data-mongodb-benchmarks/pom.xml

@@ -7,7 +7,7 @@
 	<parent>
 		<groupId>org.springframework.data</groupId>
 		<artifactId>spring-data-mongodb-parent</artifactId>
-		<version>4.2.0-SNAPSHOT</version>
+		<version>4.2.0-M2</version>
 		<relativePath>../pom.xml</relativePath>
 	</parent>
 

spring-data-mongodb-distribution/pom.xml

@@ -15,7 +15,7 @@
 	<parent>
 		<groupId>org.springframework.data</groupId>
 		<artifactId>spring-data-mongodb-parent</artifactId>
-		<version>4.2.0-SNAPSHOT</version>
+		<version>4.2.0-M2</version>
 		<relativePath>../pom.xml</relativePath>
 	</parent>
 

spring-data-mongodb/pom.xml

@@ -13,7 +13,7 @@
 	<parent>
 		<groupId>org.springframework.data</groupId>
 		<artifactId>spring-data-mongodb-parent</artifactId>
-		<version>4.2.0-SNAPSHOT</version>
+		<version>4.2.0-M2</version>
 		<relativePath>../pom.xml</relativePath>
 	</parent>
 

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

@@ -203,8 +203,9 @@ class MappingMongoJsonSchemaCreator implements MongoJsonSchemaCreator {
 								target.properties(nestedProperties.toArray(new JsonSchemaProperty[0])), required));
 					}
 				}
-				return targetProperties.size() == 1 ? targetProperties.iterator().next()
+				JsonSchemaProperty schemaProperty = targetProperties.size() == 1 ? targetProperties.iterator().next()
 						: JsonSchemaProperty.merged(targetProperties);
+				return applyEncryptionDataIfNecessary(property, schemaProperty);
 			}
 		}
 

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

@@ -63,7 +63,7 @@ class AggregationOperationRenderer {
 					contextToUse = new InheritingExposedFieldsAggregationOperationContext(fields, contextToUse);
 				} else {
 					contextToUse = fields.exposesNoFields() ? DEFAULT_CONTEXT
-							: new ExposedFieldsAggregationOperationContext(exposedFieldsOperation.getFields(), contextToUse);
+							: new ExposedFieldsAggregationOperationContext(fields, contextToUse);
 				}
 			}
 		}

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

@@ -0,0 +1,133 @@
+/*
+ * Copyright 2022-2024 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
+ *
+ *      https://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.lang.Nullable;
+import org.springframework.util.Assert;
+import org.springframework.util.ObjectUtils;
+
+/**
+ * A special field that points to a variable {@code $$} expression.
+ *
+ * @author Christoph Strobl
+ * @since 4.1.3
+ */
+public interface AggregationVariable extends Field {
+
+	String PREFIX = "$$";
+
+	/**
+	 * @return {@literal true} if the fields {@link #getName() name} does not match the defined {@link #getTarget()
+	 *         target}.
+	 */
+	@Override
+	default boolean isAliased() {
+		return !ObjectUtils.nullSafeEquals(getName(), getTarget());
+	}
+
+	@Override
+	default String getName() {
+		return getTarget();
+	}
+
+	@Override
+	default boolean isInternal() {
+		return false;
+	}
+
+	/**
+	 * Create a new {@link AggregationVariable} for the given name.
+	 * <p>
+	 * Variables start with {@code $$}. If not, the given value gets prefixed with {@code $$}.
+	 *
+	 * @param value must not be {@literal null}.
+	 * @return new instance of {@link AggregationVariable}.
+	 * @throws IllegalArgumentException if given value is {@literal null}.
+	 */
+	static AggregationVariable variable(String value) {
+
+		Assert.notNull(value, "Value must not be null");
+		return new AggregationVariable() {
+
+			private final String val = AggregationVariable.prefixVariable(value);
+
+			@Override
+			public String getTarget() {
+				return val;
+			}
+		};
+	}
+
+	/**
+	 * Create a new {@link #isInternal() local} {@link AggregationVariable} for the given name.
+	 * <p>
+	 * Variables start with {@code $$}. If not, the given value gets prefixed with {@code $$}.
+	 *
+	 * @param value must not be {@literal null}.
+	 * @return new instance of {@link AggregationVariable}.
+	 * @throws IllegalArgumentException if given value is {@literal null}.
+	 */
+	static AggregationVariable localVariable(String value) {
+
+		Assert.notNull(value, "Value must not be null");
+		return new AggregationVariable() {
+
+			private final String val = AggregationVariable.prefixVariable(value);
+
+			@Override
+			public String getTarget() {
+				return val;
+			}
+
+			@Override
+			public boolean isInternal() {
+				return true;
+			}
+		};
+	}
+
+	/**
+	 * Check if the given field name reference may be variable.
+	 *
+	 * @param fieldRef can be {@literal null}.
+	 * @return true if given value matches the variable identification pattern.
+	 */
+	static boolean isVariable(@Nullable String fieldRef) {
+		return fieldRef != null && fieldRef.stripLeading().matches("^\\$\\$\\w.*");
+	}
+
+	/**
+	 * Check if the given field may be variable.
+	 *
+	 * @param field can be {@literal null}.
+	 * @return true if given {@link Field field} is an {@link AggregationVariable} or if its value is a
+	 *         {@link #isVariable(String) variable}.
+	 */
+	static boolean isVariable(Field field) {
+
+		if (field instanceof AggregationVariable) {
+			return true;
+		}
+		return isVariable(field.getTarget());
+	}
+
+	private static String prefixVariable(String variable) {
+
+		var trimmed = variable.stripLeading();
+		return trimmed.startsWith(PREFIX) ? trimmed : (PREFIX + trimmed);
+	}
+
+}

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

@@ -1515,24 +1515,15 @@ public class ArrayOperators {
 			}
 		}
 
-		public enum Variable implements Field {
+		public enum Variable implements AggregationVariable {
 
 			THIS {
-				@Override
-				public String getName() {
-					return "$$this";
-				}
 
 				@Override
 				public String getTarget() {
 					return "$$this";
 				}
 
-				@Override
-				public boolean isAliased() {
-					return false;
-				}
-
 				@Override
 				public String toString() {
 					return getName();
@@ -1540,27 +1531,23 @@ public class ArrayOperators {
 			},
 
 			VALUE {
-				@Override
-				public String getName() {
-					return "$$value";
-				}
 
 				@Override
 				public String getTarget() {
 					return "$$value";
 				}
 
-				@Override
-				public boolean isAliased() {
-					return false;
-				}
-
 				@Override
 				public String toString() {
 					return getName();
 				}
 			};
 
+			@Override
+			public boolean isInternal() {
+				return true;
+			}
+
 			/**
 			 * Create a {@link Field} reference to a given {@literal property} prefixed with the {@link Variable} identifier.
 			 * eg. {@code $$value.product}
@@ -1592,6 +1579,16 @@ public class ArrayOperators {
 					}
 				};
 			}
+
+			public static boolean isVariable(Field field) {
+
+				for (Variable var : values()) {
+					if (field.getTarget().startsWith(var.getTarget())) {
+						return true;
+					}
+				}
+				return false;
+			}
 		}
 	}
 

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

@@ -67,7 +67,7 @@ public final class Fields implements Iterable<Field> {
 
 		Assert.notNull(names, "Field names must not be null");
 
-		List<Field> fields = new ArrayList<Field>();
+		List<Field> fields = new ArrayList<>();
 
 		for (String name : names) {
 			fields.add(field(name));
@@ -114,7 +114,7 @@ public final class Fields implements Iterable<Field> {
 
 	private static List<Field> verify(List<Field> fields) {
 
-		Map<String, Field> reference = new HashMap<String, Field>();
+		Map<String, Field> reference = new HashMap<>();
 
 		for (Field field : fields) {
 
@@ -133,7 +133,7 @@ public final class Fields implements Iterable<Field> {
 
 	private Fields(Fields existing, Field tail) {
 
-		this.fields = new ArrayList<Field>(existing.fields.size() + 1);
+		this.fields = new ArrayList<>(existing.fields.size() + 1);
 		this.fields.addAll(existing.fields);
 		this.fields.add(tail);
 	}
@@ -245,7 +245,7 @@ public final class Fields implements Iterable<Field> {
 
 		private static String cleanUp(String source) {
 
-			if (SystemVariable.isReferingToSystemVariable(source)) {
+			if (AggregationVariable.isVariable(source)) {
 				return source;
 			}
 
@@ -253,10 +253,12 @@ public final class Fields implements Iterable<Field> {
 			return dollarIndex == -1 ? source : source.substring(dollarIndex + 1);
 		}
 
+		@Override
 		public String getName() {
 			return name;
 		}
 
+		@Override
 		public String getTarget() {
 
 			if (isLocalVar() || pointsToDBRefId()) {

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

@@ -15,6 +15,7 @@
  */
 package org.springframework.data.mongodb.core.aggregation;
 
+import org.bson.Document;
 import org.springframework.data.mongodb.core.aggregation.ExposedFields.FieldReference;
 
 /**
@@ -22,6 +23,7 @@ import org.springframework.data.mongodb.core.aggregation.ExposedFields.FieldRefe
  * {@link AggregationOperationContext}.
  *
  * @author Mark Paluch
+ * @author Christoph Strobl
  * @since 1.9
  */
 class InheritingExposedFieldsAggregationOperationContext extends ExposedFieldsAggregationOperationContext {
@@ -43,6 +45,11 @@ class InheritingExposedFieldsAggregationOperationContext extends ExposedFieldsAg
 		this.previousContext = previousContext;
 	}
 
+	@Override
+	public Document getMappedObject(Document document) {
+		return previousContext.getMappedObject(document);
+	}
+
 	@Override
 	protected FieldReference resolveExposedField(Field field, String name) {
 

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

@@ -21,7 +21,6 @@ import java.util.Collections;
 import java.util.List;
 
 import org.bson.Document;
-
 import org.springframework.data.mongodb.core.aggregation.ExposedFields.ExposedField;
 import org.springframework.expression.spel.ast.Projection;
 import org.springframework.util.Assert;
@@ -431,6 +430,7 @@ public class ReplaceRootOperation implements FieldsExposingAggregationOperation
 		 * @param context will never be {@literal null}.
 		 * @return never {@literal null}.
 		 */
+		@Override
 		Document toDocument(AggregationOperationContext context);
 	}
 

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

@@ -24,7 +24,7 @@ import org.springframework.lang.Nullable;
  * @author Christoph Strobl
  * @see <a href="https://docs.mongodb.com/manual/reference/aggregation-variables">Aggregation Variables</a>.
  */
-public enum SystemVariable {
+public enum SystemVariable implements AggregationVariable {
 
 	/**
 	 * Variable for the current datetime.
@@ -82,8 +82,6 @@ public enum SystemVariable {
 	 */
 	SEARCH_META;
 
-	private static final String PREFIX = "$$";
-
 	/**
 	 * Return {@literal true} if the given {@code fieldRef} denotes a well-known system variable, {@literal false}
 	 * otherwise.
@@ -93,13 +91,12 @@ public enum SystemVariable {
 	 */
 	public static boolean isReferingToSystemVariable(@Nullable String fieldRef) {
 
-		if (fieldRef == null || !fieldRef.startsWith(PREFIX) || fieldRef.length() <= 2) {
+		String candidate = variableNameFrom(fieldRef);
+		if (candidate == null) {
 			return false;
 		}
 
-		int indexOfFirstDot = fieldRef.indexOf('.');
-		String candidate = fieldRef.substring(2, indexOfFirstDot == -1 ? fieldRef.length() : indexOfFirstDot);
-
+		candidate = candidate.startsWith(PREFIX) ? candidate.substring(2) : candidate;
 		for (SystemVariable value : values()) {
 			if (value.name().equals(candidate)) {
 				return true;
@@ -113,4 +110,20 @@ public enum SystemVariable {
 	public String toString() {
 		return PREFIX.concat(name());
 	}
+
+	@Override
+	public String getTarget() {
+		return toString();
+	}
+
+	@Nullable
+	static String variableNameFrom(@Nullable String fieldRef) {
+
+		if (fieldRef == null || !fieldRef.startsWith(PREFIX) || fieldRef.length() <= 2) {
+			return null;
+		}
+
+		int indexOfFirstDot = fieldRef.indexOf('.');
+		return indexOfFirstDot == -1 ? fieldRef : fieldRef.substring(2, indexOfFirstDot);
+	}
 }

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

@@ -133,7 +133,7 @@ public class TypeBasedAggregationOperationContext implements AggregationOperatio
 
 	protected FieldReference getReferenceFor(Field field) {
 
-		if(entity.getNullable() == null) {
+		if(entity.getNullable() == null || AggregationVariable.isVariable(field)) {
 			return new DirectFieldReference(new ExposedField(field, true));
 		}
 

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

@@ -36,6 +36,7 @@ import org.springframework.data.mongodb.core.schema.TypedJsonSchemaObject.Timest
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.ObjectUtils;
+import org.springframework.util.StringUtils;
 
 /**
  * {@link JsonSchemaProperty} implementation.
@@ -1139,7 +1140,9 @@ public class IdentifiableJsonSchemaProperty<T extends JsonSchemaObject> implemen
 				enc.append("bsonType", type.toBsonType().value()); // TODO: no samples with type -> is it bson type all the way?
 			}
 
-			enc.append("algorithm", algorithm);
+			if (StringUtils.hasText(algorithm)) {
+				enc.append("algorithm", algorithm);
+			}
 
 			propertySpecification.append("encrypt", enc);
 

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/MappingMongoJsonSchemaCreatorUnitTests.java

@@ -271,6 +271,17 @@ class MappingMongoJsonSchemaCreatorUnitTests {
 				.containsEntry("properties.value", new Document("type", "string"));
 	}
 
+	@Test // GH-4454
+	void wrapEncryptedEntityTypeLikeProperty() {
+
+		MongoJsonSchema schema = MongoJsonSchemaCreator.create() //
+				.filter(MongoJsonSchemaCreator.encryptedOnly()) // filter non encrypted fields
+				.createSchemaFor(WithEncryptedEntityLikeProperty.class);
+
+		assertThat(schema.schemaDocument()) //
+				.containsEntry("properties.domainTypeValue", Document.parse("{'encrypt': {'bsonType': 'object' } }"));
+	}
+
 	// --> TYPES AND JSON
 
 	// --> ENUM
@@ -676,4 +687,9 @@ class MappingMongoJsonSchemaCreatorUnitTests {
 	static class PropertyClashWithA {
 		Integer aNonEncrypted;
 	}
+
+	@Encrypted(algorithm = "AEAD_AES_256_CBC_HMAC_SHA_512-Deterministic")
+	static class WithEncryptedEntityLikeProperty {
+		@Encrypted SomeDomainType domainTypeValue;
+	}
 }

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/MongoTemplateValidationTests.java

@@ -33,8 +33,10 @@ import org.springframework.context.annotation.Configuration;
 import org.springframework.dao.DataIntegrityViolationException;
 import org.springframework.data.mongodb.config.AbstractMongoClientConfiguration;
 import org.springframework.data.mongodb.core.CollectionOptions.ValidationOptions;
+import org.springframework.data.mongodb.core.mapping.Encrypted;
 import org.springframework.data.mongodb.core.mapping.Field;
 import org.springframework.data.mongodb.core.query.Criteria;
+import org.springframework.data.mongodb.core.schema.MongoJsonSchema;
 import org.springframework.data.mongodb.test.util.Client;
 import org.springframework.data.mongodb.test.util.MongoClientExtension;
 import org.springframework.lang.Nullable;
@@ -46,11 +48,13 @@ import com.mongodb.client.model.ValidationLevel;
 
 /**
  * Integration tests for {@link CollectionOptions#validation(ValidationOptions)} using
- * {@link org.springframework.data.mongodb.core.validation.CriteriaValidator} and
- * {@link org.springframework.data.mongodb.core.validation.DocumentValidator}.
+ * {@link org.springframework.data.mongodb.core.validation.CriteriaValidator},
+ * {@link org.springframework.data.mongodb.core.validation.DocumentValidator} and
+ * {@link org.springframework.data.mongodb.core.validation.JsonSchemaValidator}.
  *
  * @author Andreas Zink
  * @author Christoph Strobl
+ * @author Julia Lee
  */
 @ExtendWith({ MongoClientExtension.class, SpringExtension.class })
 public class MongoTemplateValidationTests {
@@ -186,6 +190,20 @@ public class MongoTemplateValidationTests {
 		assertThat(getValidatorInfo(COLLECTION_NAME)).isEqualTo(new Document("customName", new Document("$type", "bool")));
 	}
 
+	@Test // GH-4454
+	public void failsJsonSchemaValidationForEncryptedDomainEntityProperty() {
+
+		MongoJsonSchema schema = MongoJsonSchemaCreator.create().createSchemaFor(BeanWithEncryptedDomainEntity.class);
+		template.createCollection(COLLECTION_NAME, CollectionOptions.empty().schema(schema));
+
+		BeanWithEncryptedDomainEntity person = new BeanWithEncryptedDomainEntity();
+		person.encryptedDomainEntity = new SimpleBean("some string", 100, null);
+
+		assertThatExceptionOfType(DataIntegrityViolationException.class)
+			.isThrownBy(() -> template.save(person))
+			.withMessageContaining("Document failed validation");
+	}
+
 	private Document getCollectionOptions(String collectionName) {
 		return getCollectionInfo(collectionName).get("options", Document.class);
 	}
@@ -271,4 +289,10 @@ public class MongoTemplateValidationTests {
 			return "MongoTemplateValidationTests.SimpleBean(nonNullString=" + this.getNonNullString() + ", rangedInteger=" + this.getRangedInteger() + ", customFieldName=" + this.getCustomFieldName() + ")";
 		}
 	}
+
+	@org.springframework.data.mongodb.core.mapping.Document(collection = COLLECTION_NAME)
+	@Encrypted(algorithm = "AEAD_AES_256_CBC_HMAC_SHA_512-Deterministic")
+	static class BeanWithEncryptedDomainEntity {
+		@Encrypted SimpleBean encryptedDomainEntity;
+	}
 }

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/aggregation/AggregationOperationRendererUnitTests.java

@@ -0,0 +1,118 @@
+/*
+ * Copyright 2023 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
+ *
+ *      https://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.assertj.core.api.Assertions.*;
+import static org.mockito.Mockito.*;
+
+import java.util.List;
+
+import org.assertj.core.api.InstanceOfAssertFactories;
+import org.junit.jupiter.api.Test;
+import org.mockito.ArgumentCaptor;
+import org.springframework.data.mongodb.core.aggregation.FieldsExposingAggregationOperation.InheritsFieldsAggregationOperation;
+
+/**
+ * @author Christoph Strobl
+ */
+public class AggregationOperationRendererUnitTests {
+
+	@Test // GH-4443
+	void nonFieldsExposingAggregationOperationContinuesWithSameContextForNextStage() {
+
+		AggregationOperationContext rootContext = mock(AggregationOperationContext.class);
+		AggregationOperation stage1 = mock(AggregationOperation.class);
+		AggregationOperation stage2 = mock(AggregationOperation.class);
+
+		AggregationOperationRenderer.toDocument(List.of(stage1, stage2), rootContext);
+
+		verify(stage1).toPipelineStages(eq(rootContext));
+		verify(stage2).toPipelineStages(eq(rootContext));
+	}
+
+	@Test // GH-4443
+	void fieldsExposingAggregationOperationNotExposingFieldsForcesUseOfDefaultContextForNextStage() {
+
+		AggregationOperationContext rootContext = mock(AggregationOperationContext.class);
+		FieldsExposingAggregationOperation stage1 = mock(FieldsExposingAggregationOperation.class);
+		ExposedFields stage1fields = mock(ExposedFields.class);
+		AggregationOperation stage2 = mock(AggregationOperation.class);
+
+		when(stage1.getFields()).thenReturn(stage1fields);
+		when(stage1fields.exposesNoFields()).thenReturn(true);
+
+		AggregationOperationRenderer.toDocument(List.of(stage1, stage2), rootContext);
+
+		verify(stage1).toPipelineStages(eq(rootContext));
+		verify(stage2).toPipelineStages(eq(AggregationOperationRenderer.DEFAULT_CONTEXT));
+	}
+
+	@Test // GH-4443
+	void fieldsExposingAggregationOperationForcesNewContextForNextStage() {
+
+		AggregationOperationContext rootContext = mock(AggregationOperationContext.class);
+		FieldsExposingAggregationOperation stage1 = mock(FieldsExposingAggregationOperation.class);
+		ExposedFields stage1fields = mock(ExposedFields.class);
+		AggregationOperation stage2 = mock(AggregationOperation.class);
+
+		when(stage1.getFields()).thenReturn(stage1fields);
+		when(stage1fields.exposesNoFields()).thenReturn(false);
+
+		ArgumentCaptor<AggregationOperationContext> captor = ArgumentCaptor.forClass(AggregationOperationContext.class);
+
+		AggregationOperationRenderer.toDocument(List.of(stage1, stage2), rootContext);
+
+		verify(stage1).toPipelineStages(eq(rootContext));
+		verify(stage2).toPipelineStages(captor.capture());
+
+		assertThat(captor.getValue()).isInstanceOf(ExposedFieldsAggregationOperationContext.class)
+				.isNotInstanceOf(InheritingExposedFieldsAggregationOperationContext.class);
+	}
+
+	@Test // GH-4443
+	void inheritingFieldsExposingAggregationOperationForcesNewContextForNextStageKeepingReferenceToPreviousContext() {
+
+		AggregationOperationContext rootContext = mock(AggregationOperationContext.class);
+		InheritsFieldsAggregationOperation stage1 = mock(InheritsFieldsAggregationOperation.class);
+		InheritsFieldsAggregationOperation stage2 = mock(InheritsFieldsAggregationOperation.class);
+		InheritsFieldsAggregationOperation stage3 = mock(InheritsFieldsAggregationOperation.class);
+
+		ExposedFields exposedFields = mock(ExposedFields.class);
+		when(exposedFields.exposesNoFields()).thenReturn(false);
+		when(stage1.getFields()).thenReturn(exposedFields);
+		when(stage2.getFields()).thenReturn(exposedFields);
+		when(stage3.getFields()).thenReturn(exposedFields);
+
+		ArgumentCaptor<AggregationOperationContext> captor = ArgumentCaptor.forClass(AggregationOperationContext.class);
+
+		AggregationOperationRenderer.toDocument(List.of(stage1, stage2, stage3), rootContext);
+
+		verify(stage1).toPipelineStages(captor.capture());
+		verify(stage2).toPipelineStages(captor.capture());
+		verify(stage3).toPipelineStages(captor.capture());
+
+		assertThat(captor.getAllValues().get(0)).isEqualTo(rootContext);
+
+		assertThat(captor.getAllValues().get(1))
+				.asInstanceOf(InstanceOfAssertFactories.type(InheritingExposedFieldsAggregationOperationContext.class))
+				.extracting("previousContext").isSameAs(captor.getAllValues().get(0));
+
+		assertThat(captor.getAllValues().get(2))
+				.asInstanceOf(InstanceOfAssertFactories.type(InheritingExposedFieldsAggregationOperationContext.class))
+				.extracting("previousContext").isSameAs(captor.getAllValues().get(1));
+	}
+
+}

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/aggregation/AggregationTests.java

@@ -91,6 +91,7 @@ import com.mongodb.client.MongoCollection;
  * @author Sergey Shcherbakov
  * @author Minsu Kim
  * @author Sangyong Choi
+ * @author Julia Lee
  */
 @ExtendWith(MongoTemplateExtension.class)
 public class AggregationTests {
@@ -119,7 +120,7 @@ public class AggregationTests {
 
 		mongoTemplate.flush(Product.class, UserWithLikes.class, DATAMONGO753.class, Data.class, DATAMONGO788.class,
 				User.class, Person.class, Reservation.class, Venue.class, MeterData.class, LineItem.class, InventoryItem.class,
-				Sales.class, Sales2.class, Employee.class, Art.class, Venue.class);
+				Sales.class, Sales2.class, Employee.class, Art.class, Venue.class, Item.class);
 
 		mongoTemplate.dropCollection(INPUT_COLLECTION);
 		mongoTemplate.dropCollection("personQueryTemp");
@@ -1992,6 +1993,42 @@ public class AggregationTests {
 		assertThat(aggregate.getMappedResults()).contains(widget);
 	}
 
+	@Test // GH-4443
+	void shouldHonorFieldAliasesForFieldReferencesUsingFieldExposingOperation() {
+
+		Item item1 = Item.builder().itemId("1").tags(Arrays.asList("a", "b")).build();
+		Item item2 = Item.builder().itemId("1").tags(Arrays.asList("a", "c")).build();
+		mongoTemplate.insert(Arrays.asList(item1, item2), Item.class);
+
+		TypedAggregation<Item> aggregation = newAggregation(Item.class,
+				match(where("itemId").is("1")),
+				unwind("tags"),
+				match(where("itemId").is("1").and("tags").is("c")));
+		AggregationResults<Document> results = mongoTemplate.aggregate(aggregation, Document.class);
+		List<Document> mappedResults = results.getMappedResults();
+		assertThat(mappedResults).hasSize(1);
+		assertThat(mappedResults.get(0)).containsEntry("item_id", "1");
+	}
+
+	@Test // GH-4443
+	void projectShouldResetContextToAvoidMappingFieldsAgainstANoLongerExistingTarget() {
+
+		Item item1 = Item.builder().itemId("1").tags(Arrays.asList("a", "b")).build();
+		Item item2 = Item.builder().itemId("1").tags(Arrays.asList("a", "c")).build();
+		mongoTemplate.insert(Arrays.asList(item1, item2), Item.class);
+
+		TypedAggregation<Item> aggregation = newAggregation(Item.class,
+				match(where("itemId").is("1")),
+				unwind("tags"),
+				project().and("itemId").as("itemId").and("tags").as("tags"),
+				match(where("itemId").is("1").and("tags").is("c")));
+
+		AggregationResults<Document> results = mongoTemplate.aggregate(aggregation, Document.class);
+		List<Document> mappedResults = results.getMappedResults();
+		assertThat(mappedResults).hasSize(1);
+		assertThat(mappedResults.get(0)).containsEntry("itemId", "1");
+	}
+
 	private void createUsersWithReferencedPersons() {
 
 		mongoTemplate.dropCollection(User.class);
@@ -2314,19 +2351,21 @@ public class AggregationTests {
 		}
 	}
 
-	// DATAMONGO-1491
+	// DATAMONGO-1491, GH-4443
 	static class Item {
 
 		@org.springframework.data.mongodb.core.mapping.Field("item_id") //
 		String itemId;
 		Integer quantity;
 		Long price;
+		List<String> tags = new ArrayList<>();
 
-		Item(String itemId, Integer quantity, Long price) {
+		Item(String itemId, Integer quantity, Long price, List<String> tags) {
 
 			this.itemId = itemId;
 			this.quantity = quantity;
 			this.price = price;
+			this.tags = tags;
 		}
 
 		public static ItemBuilder builder() {
@@ -2385,6 +2424,7 @@ public class AggregationTests {
 			private String itemId;
 			private Integer quantity;
 			private Long price;
+			private List<String> tags;
 
 			ItemBuilder() {}
 
@@ -2403,8 +2443,13 @@ public class AggregationTests {
 				return this;
 			}
 
+			public ItemBuilder tags(List<String> tags) {
+				this.tags = tags;
+				return this;
+			}
+
 			public Item build() {
-				return new Item(itemId, quantity, price);
+				return new Item(itemId, quantity, price, tags);
 			}
 
 			public String toString() {

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/aggregation/AggregationUnitTests.java

@@ -49,6 +49,7 @@ import com.mongodb.client.model.Projections;
  * @author Thomas Darimont
  * @author Christoph Strobl
  * @author Mark Paluch
+ * @author Julia Lee
  */
 public class AggregationUnitTests {
 
@@ -612,7 +613,7 @@ public class AggregationUnitTests {
 				WithRetypedIdField.class, mappingContext,
 				new QueryMapper(new MappingMongoConverter(NoOpDbRefResolver.INSTANCE, mappingContext)));
 		Document document = project(WithRetypedIdField.class).toDocument(context);
-		assertThat(document).isEqualTo(new Document("$project", new Document("_id", 1).append("renamed-field", 1)));
+		assertThat(document).isEqualTo(new Document("$project", new Document("_id", 1).append("renamed-field", 1).append("entries", 1)));
 	}
 
 	@Test // GH-4038
@@ -653,6 +654,22 @@ public class AggregationUnitTests {
 		assertThat(documents.get(2)).isEqualTo("{ $sort : { 'serial_number' : -1, 'label_name' : -1 } }");
 	}
 
+	@Test // GH-4443
+	void fieldsExposingContextShouldUseCustomFieldNameFromRelaxedRootContext() {
+
+		MongoMappingContext mappingContext = new MongoMappingContext();
+		RelaxedTypeBasedAggregationOperationContext context = new RelaxedTypeBasedAggregationOperationContext(
+				WithRetypedIdField.class, mappingContext,
+				new QueryMapper(new MappingMongoConverter(NoOpDbRefResolver.INSTANCE, mappingContext)));
+
+		TypedAggregation<WithRetypedIdField> agg = newAggregation(WithRetypedIdField.class,
+				unwind("entries"), match(where("foo").is("value 2")));
+		List<Document> pipeline = agg.toPipeline(context);
+
+		Document fields = getAsDocument(pipeline.get(1), "$match");
+		assertThat(fields.get("renamed-field")).isEqualTo("value 2");
+	}
+
 	private Document extractPipelineElement(Document agg, int index, String operation) {
 
 		List<Document> pipeline = (List<Document>) agg.get("pipeline");
@@ -672,5 +689,7 @@ public class AggregationUnitTests {
 
 		@org.springframework.data.mongodb.core.mapping.Field("renamed-field") private String foo;
 
+		private List<String> entries = new ArrayList<>();
+
 	}
 }

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/aggregation/AggregationVariableUnitTests.java

@@ -0,0 +1,97 @@
+/*
+ * Copyright 2022-2023 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
+ *
+ *      https://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.assertj.core.api.Assertions.*;
+
+import org.junit.jupiter.api.Test;
+import org.mockito.Mockito;
+
+/**
+ * Unit tests for {@link AggregationVariable}.
+ *
+ * @author Christoph Strobl
+ */
+class AggregationVariableUnitTests {
+
+	@Test // GH-4070
+	void variableErrorsOnNullValue() {
+		assertThatExceptionOfType(IllegalArgumentException.class).isThrownBy(() -> AggregationVariable.variable(null));
+	}
+
+	@Test // GH-4070
+	void createsVariable() {
+
+		var variable = AggregationVariable.variable("$$now");
+
+		assertThat(variable.getTarget()).isEqualTo("$$now");
+		assertThat(variable.isInternal()).isFalse();
+	}
+
+	@Test // GH-4070
+	void prefixesVariableIfNeeded() {
+
+		var variable = AggregationVariable.variable("this");
+
+		assertThat(variable.getTarget()).isEqualTo("$$this");
+	}
+
+	@Test // GH-4070
+	void localVariableErrorsOnNullValue() {
+		assertThatExceptionOfType(IllegalArgumentException.class).isThrownBy(() -> AggregationVariable.localVariable(null));
+	}
+
+	@Test // GH-4070
+	void localVariable() {
+
+		var variable = AggregationVariable.localVariable("$$this");
+
+		assertThat(variable.getTarget()).isEqualTo("$$this");
+		assertThat(variable.isInternal()).isTrue();
+	}
+
+	@Test // GH-4070
+	void prefixesLocalVariableIfNeeded() {
+
+		var variable = AggregationVariable.localVariable("this");
+
+		assertThat(variable.getTarget()).isEqualTo("$$this");
+	}
+
+	@Test // GH-4070
+	void isVariableReturnsTrueForAggregationVariableTypes() {
+
+		var variable = Mockito.mock(AggregationVariable.class);
+
+		assertThat(AggregationVariable.isVariable(variable)).isTrue();
+	}
+
+	@Test // GH-4070
+	void isVariableReturnsTrueForFieldThatTargetsVariable() {
+
+		var variable = Fields.field("value", "$$this");
+
+		assertThat(AggregationVariable.isVariable(variable)).isTrue();
+	}
+
+	@Test // GH-4070
+	void isVariableReturnsFalseForFieldThatDontTargetsVariable() {
+
+		var variable = Fields.field("value", "$this");
+
+		assertThat(AggregationVariable.isVariable(variable)).isFalse();
+	}
+}

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/aggregation/TypeBasedAggregationOperationContextUnitTests.java

@@ -37,8 +37,11 @@ import org.springframework.data.convert.CustomConversions;
 import org.springframework.data.domain.Sort;
 import org.springframework.data.domain.Sort.Direction;
 import org.springframework.data.mapping.MappingException;
+import org.springframework.data.mongodb.core.aggregation.ArrayOperators.Reduce;
+import org.springframework.data.mongodb.core.aggregation.ArrayOperators.Reduce.Variable;
 import org.springframework.data.mongodb.core.aggregation.ExposedFields.DirectFieldReference;
 import org.springframework.data.mongodb.core.aggregation.ExposedFields.ExposedField;
+import org.springframework.data.mongodb.core.aggregation.SetOperators.SetUnion;
 import org.springframework.data.mongodb.core.convert.DbRefResolver;
 import org.springframework.data.mongodb.core.convert.MappingMongoConverter;
 import org.springframework.data.mongodb.core.convert.MongoCustomConversions;
@@ -453,6 +456,30 @@ public class TypeBasedAggregationOperationContextUnitTests {
 				.isEqualTo(new Document("val", "$withUnwrapped.prefix-with-at-field-annotation"));
 	}
 
+	@Test // GH-4070
+	void rendersLocalVariables() {
+
+		AggregationOperationContext context = getContext(WithLists.class);
+
+		Document agg = newAggregation(WithLists.class,
+				project()
+						.and(Reduce.arrayOf("listOfListOfString").withInitialValue(field("listOfString"))
+								.reduce(SetUnion.arrayAsSet(Variable.VALUE.getTarget()).union(Variable.THIS.getTarget())))
+						.as("listOfString")).toDocument("collection", context);
+
+		assertThat(getPipelineElementFromAggregationAt(agg, 0).get("$project")).isEqualTo(Document.parse("""
+				{
+					"listOfString" : {
+						"$reduce" : {
+							"in" : { "$setUnion" : ["$$value", "$$this"] },
+							"initialValue" : "$listOfString",
+							"input" : "$listOfListOfString"
+						}
+					}
+				}
+				"""));
+	}
+
 	@org.springframework.data.mongodb.core.mapping.Document(collection = "person")
 	public static class FooPerson {
 
@@ -557,4 +584,9 @@ public class TypeBasedAggregationOperationContextUnitTests {
 		@org.springframework.data.mongodb.core.mapping.Field("with-at-field-annotation") //
 		String atFieldAnnotatedValue;
 	}
+
+	static class WithLists {
+		public List<String> listOfString;
+		public List<List<String>> listOfListOfString;
+	}
 }

src/main/asciidoc/reference/document-references.adoc

@@ -88,7 +88,7 @@ class Person {
 ----
 Account account = …
 
-tempate.insert(account);                               <2>
+template.insert(account);                               <2>
 
 template.update(Person.class)
   .matching(where("id").is(…))
@@ -441,7 +441,7 @@ class Entity {
   "lastname" : "Long",       <2>
 }
 ----
-<1> Read/wirte the keys `fn` & `ln` from/to the linkage document based on the lookup query.
+<1> Read/write the keys `fn` & `ln` from/to the linkage document based on the lookup query.
 <2> Use non _id_ fields for the lookup of the target documents.
 ====
 
@@ -477,7 +477,7 @@ class ToDocumentPointerConverter implements Converter<ReferencedObject, Document
   }
 }
 ----
-<1> Read/wirte the keys `_id` from/to the reference document to use them in the lookup query.
+<1> Read/write the keys `_id` from/to the reference document to use them in the lookup query.
 <2> The collection name can be read from the reference document using its key.
 ====
 

src/main/asciidoc/reference/mapping.adoc

@@ -350,6 +350,14 @@ You can add additional converters to the converter by overriding the `customConv
 MongoDB's native JSR-310 support can be enabled through `MongoConverterConfigurationAdapter.useNativeDriverJavaTimeCodecs()`.
 Also shown in the preceding example is a `LoggingEventListener`, which logs `MongoMappingEvent` instances that are posted onto Spring's `ApplicationContextEvent` infrastructure.
 
+[TIP]
+====
+.Java Time Types
+
+We recommend using MongoDB's native JSR-310 support via `MongoConverterConfigurationAdapter.useNativeDriverJavaTimeCodecs()` as described above as it is using an `UTC` based approach.
+The default JSR-310 support for `java.time` types inherited from Spring Data Commons uses the local machine timezone as reference and should only be used for backwards compatibility.
+====
+
 NOTE: `AbstractMongoClientConfiguration` creates a `MongoTemplate` instance and registers it with the container under the name `mongoTemplate`.
 
 The `base-package` property tells it where to scan for classes annotated with the `@org.springframework.data.mongodb.core.mapping.Document` annotation.

src/main/asciidoc/reference/mongo-json-schema.adoc

@@ -33,7 +33,7 @@ embedded schema objects that describe properties and subdocuments.
 <2> `required` is a property that describes which properties are required in a document. It can be specified optionally, along with other
 schema constraints. See MongoDB's documentation on https://docs.mongodb.com/manual/reference/operator/query/jsonSchema/#available-keywords[available keywords].
 <3> `properties` is related to a schema object that describes an `object` type. It contains property-specific schema constraints.
-<4> `firstname` specifies constraints for the `firsname` field inside the document. Here, it is a string-based `properties` element declaring
+<4> `firstname` specifies constraints for the `firstname` field inside the document. Here, it is a string-based `properties` element declaring
  possible field values.
 <5> `address` is a subdocument defining a schema for values in its `postCode` field.
 ====

src/main/asciidoc/reference/mongo-repositories-aggregation.adoc

@@ -77,7 +77,7 @@ Therefore, the `Sort` properties are mapped against the methods return type `Per
 <4> `$skip`, `$limit` and `$sort` can be passed on via a `Pageable` argument. Same as in <2>, the operators are appended to the pipeline definition. Methods accepting `Pageable` can return `Slice` for easier pagination.
 <5> Aggregation methods can return `Stream` to consume results directly from an underlying cursor. Make sure to close the stream after consuming it to release the server-side cursor by either calling `close()` or through `try-with-resources`.
 <6> Map the result of an aggregation returning a single `Document` to an instance of a desired `SumValue` target type.
-<7> Aggregations resulting in single document holding just an accumulation result like eg. `$sum` can be extracted directly from the result `Document`.
+<7> Aggregations resulting in single document holding just an accumulation result like e.g. `$sum` can be extracted directly from the result `Document`.
 To gain more control, you might consider `AggregationResult` as method return type as shown in <7>.
 <8> Obtain the raw `AggregationResults` mapped to the generic target wrapper type `SumValue` or `org.bson.Document`.
 <9> Like in <6>, a single value can be directly obtained from multiple result ``Document``s.

src/main/resources/notice.txt

@@ -1,4 +1,4 @@
-Spring Data MongoDB 4.2 M1 (2023.1.0)
+Spring Data MongoDB 4.2 M2 (2023.1.0)
 Copyright (c) [2010-2019] Pivotal Software, Inc.
 
 This product is licensed to you under the Apache License, Version 2.0 (the "License").
@@ -46,5 +46,6 @@ conditions of the subcomponent's license, as noted in the LICENSE file.
 
 
 
+