Support showExpandedEvents in change streams.

Expose showExpandedEvents in ChangeStreamOptions and propagate to sync/reactive change streams so expanded events can be consumed.

Closes #5069
Signed-off-by: Kyuhong Han <roy0424@naver.com>

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

@@ -53,6 +53,7 @@ public class ChangeStreamOptions {
 	private @Nullable FullDocumentBeforeChange fullDocumentBeforeChangeLookup;
 	private @Nullable Collation collation;
 	private @Nullable Object resumeTimestamp;
+	private @Nullable Boolean showExpandedEvents;
 	private Resume resume = Resume.UNDEFINED;
 
 	protected ChangeStreamOptions() {}
@@ -108,6 +109,13 @@ public class ChangeStreamOptions {
 		return Optional.ofNullable(resumeTimestamp).map(timestamp -> asTimestampOfType(timestamp, BsonTimestamp.class));
 	}
 
+	/**
+	 * @return {@link Optional#empty()} if not set.
+	 */
+	public Optional<Boolean> getShowExpandedEvents() {
+		return Optional.ofNullable(showExpandedEvents);
+	}
+
 	/**
 	 * @return {@literal true} if the change stream should be started after the {@link #getResumeToken() token}.
 	 * @since 2.2
@@ -191,6 +199,9 @@ public class ChangeStreamOptions {
 		if (!ObjectUtils.nullSafeEquals(this.resumeTimestamp, that.resumeTimestamp)) {
 			return false;
 		}
+		if (!ObjectUtils.nullSafeEquals(this.showExpandedEvents, that.showExpandedEvents)) {
+			return false;
+		}
 		return resume == that.resume;
 	}
 
@@ -202,6 +213,7 @@ public class ChangeStreamOptions {
 		result = 31 * result + ObjectUtils.nullSafeHashCode(fullDocumentBeforeChangeLookup);
 		result = 31 * result + ObjectUtils.nullSafeHashCode(collation);
 		result = 31 * result + ObjectUtils.nullSafeHashCode(resumeTimestamp);
+		result = 31 * result + ObjectUtils.nullSafeHashCode(showExpandedEvents);
 		result = 31 * result + ObjectUtils.nullSafeHashCode(resume);
 		return result;
 	}
@@ -239,6 +251,7 @@ public class ChangeStreamOptions {
 		private @Nullable FullDocumentBeforeChange fullDocumentBeforeChangeLookup;
 		private @Nullable Collation collation;
 		private @Nullable Object resumeTimestamp;
+		private @Nullable Boolean showExpandedEvents;
 		private Resume resume = Resume.UNDEFINED;
 
 		private ChangeStreamOptionsBuilder() {}
@@ -432,6 +445,19 @@ public class ChangeStreamOptions {
 			return this;
 		}
 
+		/**
+		 * Set whether expanded change events (e.g. createIndexes, shardCollection) should be emitted.
+		 *
+		 * @param showExpandedEvents {@code true} to include expanded events.
+		 * @return this.
+		 */
+		@Contract("_ -> this")
+		public ChangeStreamOptionsBuilder showExpandedEvents(boolean showExpandedEvents) {
+
+			this.showExpandedEvents = showExpandedEvents;
+			return this;
+		}
+
 		/**
 		 * @return the built {@link ChangeStreamOptions}
 		 */
@@ -446,6 +472,7 @@ public class ChangeStreamOptions {
 			options.fullDocumentBeforeChangeLookup = this.fullDocumentBeforeChangeLookup;
 			options.collation = this.collation;
 			options.resumeTimestamp = this.resumeTimestamp;
+			options.showExpandedEvents = this.showExpandedEvents;
 			options.resume = this.resume;
 
 			return options;

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

@@ -2148,6 +2148,7 @@ public class ReactiveMongoTemplate implements ReactiveMongoOperations, Applicati
 					publisher = options.getCollation().map(Collation::toMongoCollation).map(publisher::collation)
 							.orElse(publisher);
 					publisher = options.getResumeBsonTimestamp().map(publisher::startAtOperationTime).orElse(publisher);
+					publisher = options.getShowExpandedEvents().map(publisher::showExpandedEvents).orElse(publisher);
 
 					if (options.getFullDocumentBeforeChangeLookup().isPresent()) {
 						publisher = publisher.fullDocumentBeforeChange(options.getFullDocumentBeforeChangeLookup().get());

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

@@ -243,6 +243,7 @@ public class ChangeStreamRequest<T>
 		private @Nullable String databaseName;
 		private @Nullable String collectionName;
 		private @Nullable Duration maxAwaitTime;
+		private @Nullable Boolean showExpandedEvents;
 		private @Nullable MessageListener<ChangeStreamDocument<Document>, ? super T> listener;
 		private final ChangeStreamOptionsBuilder delegate = ChangeStreamOptions.builder();
 
@@ -470,6 +471,20 @@ public class ChangeStreamRequest<T>
 			return this;
 		}
 
+		/**
+		 * Set whether expanded change events (e.g. createIndexes, shardCollection) should be emitted.
+		 *
+		 * @param showExpandedEvents {@code true} to include expanded events.
+		 * @return this.
+		 */
+		@Contract("_ -> this")
+		public ChangeStreamRequestBuilder<T> showExpandedEvents(boolean showExpandedEvents) {
+
+			this.showExpandedEvents = showExpandedEvents;
+			this.delegate.showExpandedEvents(showExpandedEvents);
+			return this;
+		}
+
 		/**
 		 * @return the build {@link ChangeStreamRequest}.
 		 */

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

@@ -90,6 +90,7 @@ class ChangeStreamTask extends CursorReadingTask<ChangeStreamDocument<Document>,
 		FullDocumentBeforeChange fullDocumentBeforeChange = null;
 		BsonTimestamp startAt = null;
 		boolean resumeAfter = true;
+		boolean showExpandedEvents = false;
 
 		if (options instanceof ChangeStreamRequest.ChangeStreamRequestOptions requestOptions) {
 
@@ -105,6 +106,10 @@ class ChangeStreamTask extends CursorReadingTask<ChangeStreamDocument<Document>,
 				}
 			}
 
+			if (changeStreamOptions.getShowExpandedEvents().isPresent()) {
+				showExpandedEvents = changeStreamOptions.getShowExpandedEvents().get();
+			}
+
 			if (changeStreamOptions.getResumeToken().isPresent()) {
 
 				resumeToken = changeStreamOptions.getResumeToken().get().asDocument();
@@ -155,6 +160,10 @@ class ChangeStreamTask extends CursorReadingTask<ChangeStreamDocument<Document>,
 			iterable = iterable.collation(collation);
 		}
 
+		if (showExpandedEvents) {
+			iterable = iterable.showExpandedEvents(showExpandedEvents);
+		}
+
 		iterable = iterable.fullDocument(fullDocument);
 		if(fullDocumentBeforeChange != null) {
 			iterable = iterable.fullDocumentBeforeChange(fullDocumentBeforeChange);

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

@@ -53,4 +53,12 @@ public class ChangeStreamOptionsUnitTests {
 		assertThat(options.isResumeAfter()).isFalse();
 		assertThat(options.isStartAfter()).isFalse();
 	}
+
+	@Test // GH-5069
+	void shouldStoreShowExpandedEvents() {
+
+		ChangeStreamOptions options = ChangeStreamOptions.builder().showExpandedEvents(true).build();
+
+		assertThat(options.getShowExpandedEvents()).isPresent().hasValue(true);
+	}
 }

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

@@ -1668,6 +1668,21 @@ public class ReactiveMongoTemplateUnitTests {
 
 	}
 
+	@Test // GH-5069
+	void changeStreamOptionShowExpandedEventsShouldBeApplied() {
+
+		when(factory.getMongoDatabase(anyString())).thenReturn(Mono.just(db));
+		when(collection.watch(any(Class.class))).thenReturn(changeStreamPublisher);
+		when(changeStreamPublisher.showExpandedEvents(anyBoolean())).thenReturn(changeStreamPublisher);
+		when(changeStreamPublisher.fullDocument(any())).thenReturn(changeStreamPublisher);
+
+		ChangeStreamOptions options = ChangeStreamOptions.builder()
+				.showExpandedEvents(true).build();
+		template.changeStream("database", "collection", options, Object.class).subscribe();
+
+		verify(changeStreamPublisher).showExpandedEvents(true);
+	}
+
 	@Test // GH-4462
 	void replaceShouldUseCollationWhenPresent() {
 

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

@@ -140,6 +140,22 @@ class ChangeStreamTaskUnitTests {
 		verify(changeStreamIterable).fullDocumentBeforeChange(FullDocumentBeforeChange.REQUIRED);
 	}
 
+	@Test // GH-5069
+	void shouldApplyShowExpandedEventsToChangeStream() {
+		
+		when(changeStreamIterable.showExpandedEvents(true)).thenReturn(changeStreamIterable);
+
+		ChangeStreamRequest request = ChangeStreamRequest.builder() //
+				.collection("start-wars") //
+				.showExpandedEvents(true) //
+				.publishTo(message -> {}) //
+				.build();
+		
+		initTask(request, Document.class);
+
+		verify(changeStreamIterable).showExpandedEvents(true);
+	}
+
 	private MongoCursor<ChangeStreamDocument<Document>> initTask(ChangeStreamRequest request, Class<?> targetType) {
 
 		ChangeStreamTask task = new ChangeStreamTask(template, request, targetType, er -> {});