DATAMONGO-1855 - Polishing

Introduce base class to share code between imperative and reactive GridFs.

Original Pull Request: #637

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

@@ -49,6 +49,7 @@ import com.mongodb.reactivestreams.client.gridfs.AsyncInputStream;
  * {@link #close()} is propagated as cancellation signal to the binary {@link Publisher}.
  *
  * @author Mark Paluch
+ * @author Christoph Strobl
  * @since 2.2
  */
 @RequiredArgsConstructor
@@ -75,10 +76,10 @@ class AsyncInputStreamAdapter implements AsyncInputStream {
 			.get();
 
 	// see DEMAND
-	private volatile long demand;
+	volatile long demand;
 
 	// see SUBSCRIBED
-	private volatile int subscribed = SUBSCRIPTION_NOT_SUBSCRIBED;
+	volatile int subscribed = SUBSCRIPTION_NOT_SUBSCRIBED;
 
 	/*
 	 * (non-Javadoc)
@@ -94,20 +95,23 @@ class AsyncInputStreamAdapter implements AsyncInputStream {
 				try {
 
 					if (error != null) {
+
 						sink.error(error);
 						return;
 					}
 
 					if (bytecount == -1) {
+
 						sink.success(-1);
 						return;
 					}
 
 					ByteBuffer byteBuffer = db.asByteBuffer();
 					int toWrite = byteBuffer.remaining();
-					dst.put(byteBuffer);
 
+					dst.put(byteBuffer);
 					sink.success(toWrite);
+
 				} catch (Exception e) {
 					sink.error(e);
 				} finally {
@@ -127,6 +131,7 @@ class AsyncInputStreamAdapter implements AsyncInputStream {
 	public Publisher<Success> close() {
 
 		return Mono.create(sink -> {
+
 			cancelled = true;
 
 			if (error != null) {
@@ -141,6 +146,7 @@ class AsyncInputStreamAdapter implements AsyncInputStream {
 	protected void request(int n) {
 
 		if (complete) {
+
 			terminatePendingReads();
 			return;
 		}
@@ -150,67 +156,9 @@ class AsyncInputStreamAdapter implements AsyncInputStream {
 		if (SUBSCRIBED.get(this) == SUBSCRIPTION_NOT_SUBSCRIBED) {
 
 			if (SUBSCRIBED.compareAndSet(this, SUBSCRIPTION_NOT_SUBSCRIBED, SUBSCRIPTION_SUBSCRIBED)) {
-
-				buffers.subscribe(new CoreSubscriber<DataBuffer>() {
-
-					@Override
-					public Context currentContext() {
-						return subscriberContext;
-					}
-
-					@Override
-					public void onSubscribe(Subscription s) {
-						subscription = s;
-
-						Operators.addCap(DEMAND, AsyncInputStreamAdapter.this, -1);
-						s.request(1);
-					}
-
-					@Override
-					public void onNext(DataBuffer dataBuffer) {
-
-						if (cancelled || complete) {
-							DataBufferUtils.release(dataBuffer);
-							Operators.onNextDropped(dataBuffer, subscriberContext);
-							return;
-						}
-
-						BiConsumer<DataBuffer, Integer> poll = readRequests.poll();
-
-						if (poll == null) {
-
-							DataBufferUtils.release(dataBuffer);
-							Operators.onNextDropped(dataBuffer, subscriberContext);
-							subscription.cancel();
-							return;
-						}
-
-						poll.accept(dataBuffer, dataBuffer.readableByteCount());
-
-						requestFromSubscription(subscription);
-					}
-
-					@Override
-					public void onError(Throwable t) {
-
-						if (cancelled || complete) {
-							Operators.onErrorDropped(t, subscriberContext);
-							return;
-						}
-
-						error = t;
-						complete = true;
-						terminatePendingReads();
-					}
-
-					@Override
-					public void onComplete() {
-
-						complete = true;
-						terminatePendingReads();
-					}
-				});
+				buffers.subscribe(new DataBufferCoreSubscriber());
 			}
+
 		} else {
 
 			Subscription subscription = this.subscription;
@@ -245,4 +193,65 @@ class AsyncInputStreamAdapter implements AsyncInputStream {
 			readers.accept(factory.wrap(new byte[0]), -1);
 		}
 	}
+
+	private class DataBufferCoreSubscriber implements CoreSubscriber<DataBuffer> {
+
+		@Override
+		public Context currentContext() {
+			return AsyncInputStreamAdapter.this.subscriberContext;
+		}
+
+		@Override
+		public void onSubscribe(Subscription s) {
+
+			AsyncInputStreamAdapter.this.subscription = s;
+
+			Operators.addCap(DEMAND, AsyncInputStreamAdapter.this, -1);
+			s.request(1);
+		}
+
+		@Override
+		public void onNext(DataBuffer dataBuffer) {
+
+			if (cancelled || complete) {
+				DataBufferUtils.release(dataBuffer);
+				Operators.onNextDropped(dataBuffer, AsyncInputStreamAdapter.this.subscriberContext);
+				return;
+			}
+
+			BiConsumer<DataBuffer, Integer> poll = AsyncInputStreamAdapter.this.readRequests.poll();
+
+			if (poll == null) {
+
+				DataBufferUtils.release(dataBuffer);
+				Operators.onNextDropped(dataBuffer, AsyncInputStreamAdapter.this.subscriberContext);
+				subscription.cancel();
+				return;
+			}
+
+			poll.accept(dataBuffer, dataBuffer.readableByteCount());
+
+			requestFromSubscription(subscription);
+		}
+
+		@Override
+		public void onError(Throwable t) {
+
+			if (AsyncInputStreamAdapter.this.cancelled || AsyncInputStreamAdapter.this.complete) {
+				Operators.onErrorDropped(t, AsyncInputStreamAdapter.this.subscriberContext);
+				return;
+			}
+
+			AsyncInputStreamAdapter.this.error = t;
+			AsyncInputStreamAdapter.this.complete = true;
+			terminatePendingReads();
+		}
+
+		@Override
+		public void onComplete() {
+
+			AsyncInputStreamAdapter.this.complete = true;
+			terminatePendingReads();
+		}
+	}
 }

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

@@ -39,6 +39,7 @@ import com.mongodb.reactivestreams.client.gridfs.AsyncInputStream;
  * Utility to adapt a {@link AsyncInputStream} to a {@link Publisher} emitting {@link DataBuffer}.
  *
  * @author Mark Paluch
+ * @author Christoph Strobl
  * @since 2.2
  */
 class DataBufferPublisherAdapter {
@@ -51,7 +52,7 @@ class DataBufferPublisherAdapter {
 	 * @param dataBufferFactory must not be {@literal null}.
 	 * @return the resulting {@link Publisher}.
 	 */
-	public static Flux<DataBuffer> createBinaryStream(AsyncInputStream inputStream, DataBufferFactory dataBufferFactory) {
+	static Flux<DataBuffer> createBinaryStream(AsyncInputStream inputStream, DataBufferFactory dataBufferFactory) {
 
 		State state = new State(inputStream, dataBufferFactory);
 
@@ -73,17 +74,17 @@ class DataBufferPublisherAdapter {
 	@RequiredArgsConstructor
 	static class State {
 
-		static final AtomicLongFieldUpdater<State> DEMAND = AtomicLongFieldUpdater.newUpdater(State.class, "demand");
+		private static final AtomicLongFieldUpdater<State> DEMAND = AtomicLongFieldUpdater.newUpdater(State.class, "demand");
 
-		static final AtomicIntegerFieldUpdater<State> STATE = AtomicIntegerFieldUpdater.newUpdater(State.class, "state");
+		private static final AtomicIntegerFieldUpdater<State> STATE = AtomicIntegerFieldUpdater.newUpdater(State.class, "state");
 
-		static final AtomicIntegerFieldUpdater<State> READ = AtomicIntegerFieldUpdater.newUpdater(State.class, "read");
+		private static final AtomicIntegerFieldUpdater<State> READ = AtomicIntegerFieldUpdater.newUpdater(State.class, "read");
 
-		static final int STATE_OPEN = 0;
-		static final int STATE_CLOSED = 1;
+		private static final int STATE_OPEN = 0;
+		private static final int STATE_CLOSED = 1;
 
-		static final int READ_NONE = 0;
-		static final int READ_IN_PROGRESS = 1;
+		private static final int READ_NONE = 0;
+		private static final int READ_IN_PROGRESS = 1;
 
 		final AsyncInputStream inputStream;
 		final DataBufferFactory dataBufferFactory;
@@ -140,66 +141,79 @@ class DataBufferPublisherAdapter {
 			DataBuffer dataBuffer = dataBufferFactory.allocateBuffer();
 			ByteBuffer intermediate = ByteBuffer.allocate(dataBuffer.capacity());
 
-			Mono.from(inputStream.read(intermediate)).subscribe(new CoreSubscriber<Integer>() {
+			Mono.from(inputStream.read(intermediate)).subscribe(new BufferCoreSubscriber(sink, dataBuffer, intermediate));
+		}
 
-				@Override
-				public Context currentContext() {
-					return sink.currentContext();
-				}
+		private class BufferCoreSubscriber implements CoreSubscriber<Integer> {
 
-				@Override
-				public void onSubscribe(Subscription s) {
-					s.request(1);
-				}
+			private final FluxSink<DataBuffer> sink;
+			private final DataBuffer dataBuffer;
+			private final ByteBuffer intermediate;
 
-				@Override
-				public void onNext(Integer bytes) {
+			BufferCoreSubscriber(FluxSink<DataBuffer> sink, DataBuffer dataBuffer, ByteBuffer intermediate) {
 
-					if (isClosed()) {
+				this.sink = sink;
+				this.dataBuffer = dataBuffer;
+				this.intermediate = intermediate;
+			}
 
-						onReadDone();
-						DataBufferUtils.release(dataBuffer);
-						Operators.onNextDropped(dataBuffer, sink.currentContext());
-						return;
-					}
+			@Override
+			public Context currentContext() {
+				return sink.currentContext();
+			}
 
-					intermediate.flip();
-					dataBuffer.write(intermediate);
+			@Override
+			public void onSubscribe(Subscription s) {
+				s.request(1);
+			}
 
-					sink.next(dataBuffer);
+			@Override
+			public void onNext(Integer bytes) {
 
-					try {
-						if (bytes == -1) {
-							sink.complete();
-						}
-					} finally {
-						onReadDone();
-					}
+				if (isClosed()) {
+
+					onReadDone();
+					DataBufferUtils.release(dataBuffer);
+					Operators.onNextDropped(dataBuffer, sink.currentContext());
+					return;
 				}
 
-				@Override
-				public void onError(Throwable t) {
+				intermediate.flip();
+				dataBuffer.write(intermediate);
 
-					if (isClosed()) {
+				sink.next(dataBuffer);
 
-						Operators.onErrorDropped(t, sink.currentContext());
-						return;
+				try {
+					if (bytes == -1) {
+						sink.complete();
 					}
-
+				} finally {
 					onReadDone();
-					DataBufferUtils.release(dataBuffer);
-					Operators.onNextDropped(dataBuffer, sink.currentContext());
-					sink.error(t);
 				}
+			}
 
-				@Override
-				public void onComplete() {
+			@Override
+			public void onError(Throwable t) {
 
-					if (onShouldRead()) {
-						emitNext(sink);
-					}
+				if (isClosed()) {
+
+					Operators.onErrorDropped(t, sink.currentContext());
+					return;
 				}
-			});
+
+				onReadDone();
+				DataBufferUtils.release(dataBuffer);
+				Operators.onNextDropped(dataBuffer, sink.currentContext());
+				sink.error(t);
+			}
+
+			@Override
+			public void onComplete() {
+
+				if (onShouldRead()) {
+					emitNext(sink);
+				}
+			}
 		}
 	}
 }

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

@@ -0,0 +1,104 @@
+/*
+ * Copyright 2019 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.gridfs;
+
+import java.util.Optional;
+
+import org.bson.Document;
+import org.springframework.data.mongodb.core.convert.MongoConverter;
+import org.springframework.data.mongodb.core.convert.QueryMapper;
+import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
+import org.springframework.util.StringUtils;
+
+import com.mongodb.client.gridfs.model.GridFSUploadOptions;
+
+/**
+ * Base class offering common tasks like query mapping and {@link GridFSUploadOptions} computation to be shared across
+ * imperative and reactive implementations.
+ *
+ * @author Christoph Strobl
+ * @since 2.2
+ */
+class GridFsOperationsSupport {
+
+	private final QueryMapper queryMapper;
+	private final MongoConverter converter;
+
+	/**
+	 * @param converter must not be {@literal null}.
+	 */
+	GridFsOperationsSupport(MongoConverter converter) {
+
+		Assert.notNull(converter, "MongoConverter must not be null!");
+
+		this.converter = converter;
+		this.queryMapper = new QueryMapper(converter);
+	}
+
+	/**
+	 * @param query pass the given query though a {@link QueryMapper} to apply type conversion.
+	 * @return never {@literal null}.
+	 */
+	protected Document getMappedQuery(Document query) {
+		return queryMapper.getMappedObject(query, Optional.empty());
+	}
+
+	/**
+	 * Compute the {@link GridFSUploadOptions} to be used from the given {@literal contentType} and {@literal metadata}
+	 * {@link Document}.
+	 *
+	 * @param contentType can be {@literal null}.
+	 * @param metadata can be {@literal null}
+	 * @return never {@literal null}.
+	 */
+	protected GridFSUploadOptions computeUploadOptionsFor(@Nullable String contentType, @Nullable Document metadata) {
+
+		Document targetMetadata = new Document();
+
+		if (StringUtils.hasText(contentType)) {
+			targetMetadata.put(GridFsResource.CONTENT_TYPE_FIELD, contentType);
+		}
+
+		if (metadata != null) {
+			targetMetadata.putAll(metadata);
+		}
+
+		GridFSUploadOptions options = new GridFSUploadOptions();
+		options.metadata(targetMetadata);
+
+		return options;
+	}
+
+	/**
+	 * Convert a given {@literal value} into a {@link Document}.
+	 *
+	 * @param value can be {@literal null}.
+	 * @return an empty {@link Document} if the source value is {@literal null}.
+	 */
+	protected Document toDocument(@Nullable Object value) {
+
+		if (value instanceof Document) {
+			return (Document) value;
+		}
+
+		Document document = new Document();
+		if (value != null) {
+			converter.write(value, document);
+		}
+		return document;
+	}
+}

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

@@ -29,7 +29,6 @@ import org.bson.types.ObjectId;
 import org.springframework.core.io.support.ResourcePatternResolver;
 import org.springframework.data.mongodb.MongoDbFactory;
 import org.springframework.data.mongodb.core.convert.MongoConverter;
-import org.springframework.data.mongodb.core.convert.QueryMapper;
 import org.springframework.data.mongodb.core.query.Query;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
@@ -40,7 +39,6 @@ import com.mongodb.client.gridfs.GridFSBucket;
 import com.mongodb.client.gridfs.GridFSBuckets;
 import com.mongodb.client.gridfs.GridFSFindIterable;
 import com.mongodb.client.gridfs.model.GridFSFile;
-import com.mongodb.client.gridfs.model.GridFSUploadOptions;
 
 /**
  * {@link GridFsOperations} implementation to store content into MongoDB GridFS.
@@ -54,13 +52,11 @@ import com.mongodb.client.gridfs.model.GridFSUploadOptions;
  * @author Hartmut Lang
  * @author Niklas Helge Hanft
  */
-public class GridFsTemplate implements GridFsOperations, ResourcePatternResolver {
+public class GridFsTemplate extends GridFsOperationsSupport implements GridFsOperations, ResourcePatternResolver {
 
 	private final MongoDbFactory dbFactory;
 
 	private final @Nullable String bucket;
-	private final MongoConverter converter;
-	private final QueryMapper queryMapper;
 
 	/**
 	 * Creates a new {@link GridFsTemplate} using the given {@link MongoDbFactory} and {@link MongoConverter}.
@@ -81,14 +77,12 @@ public class GridFsTemplate implements GridFsOperations, ResourcePatternResolver
 	 */
 	public GridFsTemplate(MongoDbFactory dbFactory, MongoConverter converter, @Nullable String bucket) {
 
+		super(converter);
+
 		Assert.notNull(dbFactory, "MongoDbFactory must not be null!");
-		Assert.notNull(converter, "MongoConverter must not be null!");
 
 		this.dbFactory = dbFactory;
-		this.converter = converter;
 		this.bucket = bucket;
-
-		this.queryMapper = new QueryMapper(converter);
 	}
 
 	/*
@@ -137,16 +131,9 @@ public class GridFsTemplate implements GridFsOperations, ResourcePatternResolver
 	 * (non-Javadoc)
 	 * @see org.springframework.data.mongodb.gridfs.GridFsOperations#store(java.io.InputStream, java.lang.String, java.lang.String, java.lang.Object)
 	 */
-	public ObjectId store(InputStream content, @Nullable String filename, @Nullable String contentType, @Nullable Object metadata) {
-
-		Document document = null;
-
-		if (metadata != null) {
-			document = new Document();
-			converter.write(metadata, document);
-		}
-
-		return store(content, filename, contentType, document);
+	public ObjectId store(InputStream content, @Nullable String filename, @Nullable String contentType,
+			@Nullable Object metadata) {
+		return store(content, filename, contentType, toDocument(metadata));
 	}
 
 	/*
@@ -161,25 +148,11 @@ public class GridFsTemplate implements GridFsOperations, ResourcePatternResolver
 	 * (non-Javadoc)
 	 * @see org.springframework.data.mongodb.gridfs.GridFsOperations#store(java.io.InputStream, java.lang.String, com.mongodb.Document)
 	 */
-	public ObjectId store(InputStream content, @Nullable String filename, @Nullable String contentType, @Nullable Document metadata) {
+	public ObjectId store(InputStream content, @Nullable String filename, @Nullable String contentType,
+			@Nullable Document metadata) {
 
 		Assert.notNull(content, "InputStream must not be null!");
-
-		GridFSUploadOptions options = new GridFSUploadOptions();
-
-		Document mData = new Document();
-
-		if (StringUtils.hasText(contentType)) {
-			mData.put(GridFsResource.CONTENT_TYPE_FIELD, contentType);
-		}
-
-		if (metadata != null) {
-			mData.putAll(metadata);
-		}
-
-		options.metadata(mData);
-
-		return getGridFs().uploadFromStream(filename, content, options);
+		return getGridFs().uploadFromStream(filename, content, computeUploadOptionsFor(contentType, metadata));
 	}
 
 	/*
@@ -210,8 +183,8 @@ public class GridFsTemplate implements GridFsOperations, ResourcePatternResolver
 	 */
 	public void delete(Query query) {
 
-		for (GridFSFile x : find(query)) {
-			getGridFs().delete(((BsonObjectId) x.getId()).getValue());
+		for (GridFSFile gridFSFile : find(query)) {
+			getGridFs().delete(((BsonObjectId) gridFSFile.getId()).getValue());
 		}
 	}
 
@@ -246,9 +219,9 @@ public class GridFsTemplate implements GridFsOperations, ResourcePatternResolver
 	}
 
 	/*
-     * (non-Javadoc)
-     * @see org.springframework.core.io.support.ResourcePatternResolver#getResources(java.lang.String)
-     */
+	 * (non-Javadoc)
+	 * @see org.springframework.core.io.support.ResourcePatternResolver#getResources(java.lang.String)
+	 */
 	public GridFsResource[] getResources(String locationPattern) {
 
 		if (!StringUtils.hasText(locationPattern)) {
@@ -272,10 +245,6 @@ public class GridFsTemplate implements GridFsOperations, ResourcePatternResolver
 		return new GridFsResource[] { getResource(locationPattern) };
 	}
 
-	private Document getMappedQuery(Document query) {
-		return queryMapper.getMappedObject(query, Optional.empty());
-	}
-
 	private GridFSBucket getGridFs() {
 
 		MongoDatabase db = dbFactory.getDb();

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

@@ -22,12 +22,10 @@ import org.bson.Document;
 import org.bson.types.ObjectId;
 import org.reactivestreams.Publisher;
 import org.springframework.core.io.buffer.DataBuffer;
-import org.springframework.core.io.support.ResourcePatternResolver;
 import org.springframework.data.domain.Sort;
 import org.springframework.data.mongodb.core.query.Query;
 import org.springframework.lang.Nullable;
 
-import com.mongodb.client.gridfs.GridFSFindIterable;
 import com.mongodb.client.gridfs.model.GridFSFile;
 import com.mongodb.reactivestreams.client.gridfs.AsyncInputStream;
 
@@ -35,6 +33,7 @@ import com.mongodb.reactivestreams.client.gridfs.AsyncInputStream;
  * Collection of operations to store and read files from MongoDB GridFS using reactive infrastructure.
  *
  * @author Mark Paluch
+ * @author Christoph Strobl
  * @since 2.2
  */
 public interface ReactiveGridFsOperations {
@@ -44,29 +43,32 @@ public interface ReactiveGridFsOperations {
 	 *
 	 * @param content must not be {@literal null}.
 	 * @param filename must not be {@literal null} or empty.
-	 * @return the {@link ObjectId} of the {@link com.mongodb.client.gridfs.model.GridFSFile} just created.
+	 * @return a {@link Mono} emitting the {@link ObjectId} of the {@link com.mongodb.client.gridfs.model.GridFSFile} just
+	 *         created.
 	 */
 	default Mono<ObjectId> store(Publisher<DataBuffer> content, String filename) {
 		return store(content, filename, (Object) null);
 	}
 
 	/**
-	 * Stores the given content into a file with the given name.
+	 * Stores the given content into a file applying the given metadata.
 	 *
 	 * @param content must not be {@literal null}.
 	 * @param metadata can be {@literal null}.
-	 * @return the {@link ObjectId} of the {@link com.mongodb.client.gridfs.model.GridFSFile} just created.
+	 * @return a {@link Mono} emitting the {@link ObjectId} of the {@link com.mongodb.client.gridfs.model.GridFSFile} just
+	 *         created.
 	 */
 	default Mono<ObjectId> store(Publisher<DataBuffer> content, @Nullable Object metadata) {
 		return store(content, null, metadata);
 	}
 
 	/**
-	 * Stores the given content into a file with the given name.
+	 * Stores the given content into a file applying the given metadata.
 	 *
 	 * @param content must not be {@literal null}.
 	 * @param metadata can be {@literal null}.
-	 * @return the {@link ObjectId} of the {@link com.mongodb.client.gridfs.model.GridFSFile} just created.
+	 * @return a {@link Mono} emitting the {@link ObjectId} of the {@link com.mongodb.client.gridfs.model.GridFSFile} just
+	 *         created.
 	 */
 	default Mono<ObjectId> store(Publisher<DataBuffer> content, @Nullable Document metadata) {
 		return store(content, null, metadata);
@@ -78,7 +80,8 @@ public interface ReactiveGridFsOperations {
 	 * @param content must not be {@literal null}.
 	 * @param filename must not be {@literal null} or empty.
 	 * @param contentType can be {@literal null}.
-	 * @return the {@link ObjectId} of the {@link com.mongodb.client.gridfs.model.GridFSFile} just created.
+	 * @return a {@link Mono} emitting the {@link ObjectId} of the {@link com.mongodb.client.gridfs.model.GridFSFile} just
+	 *         created.
 	 */
 	default Mono<ObjectId> store(Publisher<DataBuffer> content, @Nullable String filename, @Nullable String contentType) {
 		return store(content, filename, contentType, (Object) null);
@@ -91,7 +94,8 @@ public interface ReactiveGridFsOperations {
 	 * @param content must not be {@literal null}.
 	 * @param filename can be {@literal null} or empty.
 	 * @param metadata can be {@literal null}.
-	 * @return the {@link ObjectId} of the {@link com.mongodb.client.gridfs.model.GridFSFile} just created.
+	 * @return a {@link Mono} emitting the {@link ObjectId} of the {@link com.mongodb.client.gridfs.model.GridFSFile} just
+	 *         created.
 	 */
 	default Mono<ObjectId> store(Publisher<DataBuffer> content, @Nullable String filename, @Nullable Object metadata) {
 		return store(content, filename, null, metadata);
@@ -105,7 +109,8 @@ public interface ReactiveGridFsOperations {
 	 * @param filename must not be {@literal null} or empty.
 	 * @param contentType can be {@literal null}.
 	 * @param metadata can be {@literal null}
-	 * @return the {@link ObjectId} of the {@link com.mongodb.client.gridfs.model.GridFSFile} just created.
+	 * @return a {@link Mono} emitting the {@link ObjectId} of the {@link com.mongodb.client.gridfs.model.GridFSFile} just
+	 *         created.
 	 */
 	Mono<ObjectId> store(AsyncInputStream content, @Nullable String filename, @Nullable String contentType,
 			@Nullable Object metadata);
@@ -118,7 +123,8 @@ public interface ReactiveGridFsOperations {
 	 * @param filename must not be {@literal null} or empty.
 	 * @param contentType can be {@literal null}.
 	 * @param metadata can be {@literal null}
-	 * @return the {@link ObjectId} of the {@link com.mongodb.client.gridfs.model.GridFSFile} just created.
+	 * @return a {@link Mono} emitting the {@link ObjectId} of the {@link com.mongodb.client.gridfs.model.GridFSFile} just
+	 *         created.
 	 */
 	Mono<ObjectId> store(Publisher<DataBuffer> content, @Nullable String filename, @Nullable String contentType,
 			@Nullable Object metadata);
@@ -129,7 +135,8 @@ public interface ReactiveGridFsOperations {
 	 * @param content must not be {@literal null}.
 	 * @param filename must not be {@literal null} or empty.
 	 * @param metadata can be {@literal null}.
-	 * @return the {@link ObjectId} of the {@link com.mongodb.client.gridfs.model.GridFSFile} just created.
+	 * @return a {@link Mono} emitting the {@link ObjectId} of the {@link com.mongodb.client.gridfs.model.GridFSFile} just
+	 *         created.
 	 */
 	default Mono<ObjectId> store(Publisher<DataBuffer> content, @Nullable String filename, @Nullable Document metadata) {
 		return store(content, filename, null, metadata);
@@ -142,63 +149,85 @@ public interface ReactiveGridFsOperations {
 	 * @param filename must not be {@literal null} or empty.
 	 * @param contentType can be {@literal null}.
 	 * @param metadata can be {@literal null}.
-	 * @return the {@link ObjectId} of the {@link com.mongodb.client.gridfs.model.GridFSFile} just created.
+	 * @return a {@link Mono} emitting the {@link ObjectId} of the {@link com.mongodb.client.gridfs.model.GridFSFile} just
+	 *         created.
 	 */
 	Mono<ObjectId> store(AsyncInputStream content, @Nullable String filename, @Nullable String contentType,
 			@Nullable Document metadata);
 
-	Mono<ObjectId> store(Publisher<DataBuffer> content, String filename, String contentType, Document metadata);
+	/**
+	 * Stores the given content into a file with the given name and content type using the given metadata.
+	 *
+	 * @param content must not be {@literal null}.
+	 * @param filename must not be {@literal null} or empty.
+	 * @param contentType can be {@literal null}.
+	 * @param metadata can be {@literal null}.
+	 * @return a {@link Mono} emitting the {@link ObjectId} of the {@link com.mongodb.client.gridfs.model.GridFSFile} just
+	 *         created.
+	 */
+	Mono<ObjectId> store(Publisher<DataBuffer> content, @Nullable String filename, @Nullable String contentType,
+			@Nullable Document metadata);
 
 	/**
-	 * Returns all files matching the given query. Note, that currently {@link Sort} criterias defined at the
-	 * {@link Query} will not be regarded as MongoDB does not support ordering for GridFS file access.
+	 * Returns a {@link Flux} emitting all files matching the given query. <br />
+	 * <strong>Note:</strong> Currently {@link Sort} criteria defined at the {@link Query} will not be regarded as MongoDB
+	 * does not support ordering for GridFS file access.
 	 *
 	 * @see <a href="https://jira.mongodb.org/browse/JAVA-431">MongoDB Jira: JAVA-431</a>
 	 * @param query must not be {@literal null}.
-	 * @return {@link GridFSFindIterable} to obtain results from. Eg. by calling
-	 *         {@link GridFSFindIterable#into(java.util.Collection)}.
+	 * @return {@link Flux#empty()} if no mach found.
 	 */
 	Flux<GridFSFile> find(Query query);
 
 	/**
-	 * Returns a single {@link com.mongodb.client.gridfs.model.GridFSFile} matching the given query or {@literal null} in
-	 * case no file matches.
+	 * Returns a {@link Mono} emitting a single {@link com.mongodb.client.gridfs.model.GridFSFile} matching the given
+	 * query or {@link Mono#empty()} in case no file matches. <br />
+	 * <strong>NOTE</strong> If more than one file matches the given query the resulting {@link Mono} emits an error. If
+	 * you want to obtain the first found file use {@link #findFirst(Query)}.
 	 *
 	 * @param query must not be {@literal null}.
-	 * @return
+	 * @return {@link Mono#empty()} if not match found.
 	 */
 	Mono<GridFSFile> findOne(Query query);
 
+	/**
+	 * Returns a {@link Mono} emitting the frist {@link com.mongodb.client.gridfs.model.GridFSFile} matching the given
+	 * query or {@link Mono#empty()} in case no file matches.
+	 *
+	 * @param query must not be {@literal null}.
+	 * @return {@link Mono#empty()} if not match found.
+	 */
+	Mono<GridFSFile> findFirst(Query query);
+
 	/**
 	 * Deletes all files matching the given {@link Query}.
 	 *
 	 * @param query must not be {@literal null}.
+	 * @return a {@link Mono} signalling operation completion.
 	 */
 	Mono<Void> delete(Query query);
 
 	/**
-	 * Returns the {@link GridFsResource} with the given file name.
+	 * Returns a {@link Mono} emitting the {@link ReactiveGridFsResource} with the given file name.
 	 *
 	 * @param filename must not be {@literal null}.
-	 * @return the resource. Use {@link org.springframework.core.io.Resource#exists()} to check if the returned
-	 *         {@link GridFsResource} is actually present.
-	 * @see ResourcePatternResolver#getResource(String)
+	 * @return {@link Mono#empty()} if no match found.
 	 */
 	Mono<ReactiveGridFsResource> getResource(String filename);
 
 	/**
-	 * Returns the {@link GridFsResource} for a {@link GridFSFile}.
+	 * Returns a {@link Mono} emitting the {@link ReactiveGridFsResource} for a {@link GridFSFile}.
 	 *
 	 * @param file must not be {@literal null}.
-	 * @return the resource for the file.
+	 * @return {@link Mono#empty()} if no match found.
 	 */
 	Mono<ReactiveGridFsResource> getResource(GridFSFile file);
 
 	/**
-	 * Returns all {@link GridFsResource}s matching the given file name pattern.
+	 * Returns a {@link Flux} emitting all {@link ReactiveGridFsResource}s matching the given file name pattern.
 	 *
 	 * @param filenamePattern must not be {@literal null}.
-	 * @return
+	 * @return {@link Flux#empty()} if no match found.
 	 */
 	Flux<ReactiveGridFsResource> getResources(String filenamePattern);
 }

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

@@ -21,24 +21,22 @@ import static org.springframework.data.mongodb.gridfs.GridFsCriteria.*;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 
-import java.util.Optional;
-
 import org.bson.Document;
 import org.bson.types.ObjectId;
 import org.reactivestreams.Publisher;
 import org.springframework.core.io.buffer.DataBuffer;
 import org.springframework.core.io.buffer.DataBufferFactory;
 import org.springframework.core.io.buffer.DefaultDataBufferFactory;
+import org.springframework.dao.IncorrectResultSizeDataAccessException;
 import org.springframework.data.mongodb.ReactiveMongoDatabaseFactory;
 import org.springframework.data.mongodb.core.convert.MongoConverter;
-import org.springframework.data.mongodb.core.convert.QueryMapper;
 import org.springframework.data.mongodb.core.query.Query;
+import org.springframework.data.mongodb.core.query.SerializationUtils;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
 
 import com.mongodb.client.gridfs.model.GridFSFile;
-import com.mongodb.client.gridfs.model.GridFSUploadOptions;
 import com.mongodb.reactivestreams.client.MongoDatabase;
 import com.mongodb.reactivestreams.client.gridfs.AsyncInputStream;
 import com.mongodb.reactivestreams.client.gridfs.GridFSBucket;
@@ -53,13 +51,11 @@ import com.mongodb.reactivestreams.client.gridfs.GridFSFindPublisher;
  * @author Mark Paluch
  * @since 2.2
  */
-public class ReactiveGridFsTemplate implements ReactiveGridFsOperations {
+public class ReactiveGridFsTemplate extends GridFsOperationsSupport implements ReactiveGridFsOperations {
 
-	private final DataBufferFactory dataBufferFactory;
 	private final ReactiveMongoDatabaseFactory dbFactory;
+	private final DataBufferFactory dataBufferFactory;
 	private final @Nullable String bucket;
-	private final MongoConverter converter;
-	private final QueryMapper queryMapper;
 
 	/**
 	 * Creates a new {@link ReactiveGridFsTemplate} using the given {@link ReactiveMongoDatabaseFactory} and
@@ -97,16 +93,14 @@ public class ReactiveGridFsTemplate implements ReactiveGridFsOperations {
 	public ReactiveGridFsTemplate(DataBufferFactory dataBufferFactory, ReactiveMongoDatabaseFactory dbFactory,
 			MongoConverter converter, @Nullable String bucket) {
 
+		super(converter);
+
 		Assert.notNull(dataBufferFactory, "DataBufferFactory must not be null!");
 		Assert.notNull(dbFactory, "ReactiveMongoDatabaseFactory must not be null!");
-		Assert.notNull(converter, "MongoConverter must not be null!");
 
 		this.dataBufferFactory = dataBufferFactory;
 		this.dbFactory = dbFactory;
-		this.converter = converter;
 		this.bucket = bucket;
-
-		this.queryMapper = new QueryMapper(converter);
 	}
 
 	/*
@@ -138,22 +132,7 @@ public class ReactiveGridFsTemplate implements ReactiveGridFsOperations {
 			@Nullable Document metadata) {
 
 		Assert.notNull(content, "InputStream must not be null!");
-
-		GridFSUploadOptions options = new GridFSUploadOptions();
-
-		Document mData = new Document();
-
-		if (StringUtils.hasText(contentType)) {
-			mData.put(GridFsResource.CONTENT_TYPE_FIELD, contentType);
-		}
-
-		if (metadata != null) {
-			mData.putAll(metadata);
-		}
-
-		options.metadata(mData);
-
-		return Mono.from(getGridFs().uploadFromStream(filename, content, options));
+		return Mono.from(getGridFs().uploadFromStream(filename, content, computeUploadOptionsFor(contentType, metadata)));
 	}
 
 	/*
@@ -175,10 +154,7 @@ public class ReactiveGridFsTemplate implements ReactiveGridFsOperations {
 	 */
 	@Override
 	public Flux<GridFSFile> find(Query query) {
-
-		GridFSFindPublisher publisherToUse = prepareQuery(query);
-
-		return Flux.from(publisherToUse);
+		return Flux.from(prepareQuery(query));
 	}
 
 	/*
@@ -188,9 +164,29 @@ public class ReactiveGridFsTemplate implements ReactiveGridFsOperations {
 	@Override
 	public Mono<GridFSFile> findOne(Query query) {
 
-		GridFSFindPublisher publisherToUse = prepareQuery(query);
+		return Flux.from(prepareQuery(query).limit(2)) //
+				.collectList() //
+				.flatMap(it -> {
+					if (it.isEmpty()) {
+						return Mono.empty();
+					}
 
-		return Flux.from(publisherToUse.limit(1)).next();
+					if (it.size() > 1) {
+						return Mono.error(new IncorrectResultSizeDataAccessException(
+								"Query " + SerializationUtils.serializeToJsonSafely(query) + " returned non unique result.", 1));
+					}
+
+					return Mono.just(it.get(0));
+				});
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.gridfs.ReactiveGridFsOperations#findFirst(org.springframework.data.mongodb.core.query.Query)
+	 */
+	@Override
+	public Mono<GridFSFile> findFirst(Query query) {
+		return Flux.from(prepareQuery(query).limit(1)).next();
 	}
 
 	/*
@@ -199,9 +195,7 @@ public class ReactiveGridFsTemplate implements ReactiveGridFsOperations {
 	 */
 	@Override
 	public Mono<Void> delete(Query query) {
-
-		GridFSBucket gridFs = getGridFs();
-		return find(query).flatMap(it -> gridFs.delete(it.getId())).then();
+		return find(query).flatMap(it -> getGridFs().delete(it.getId())).then();
 	}
 
 	/*
@@ -273,25 +267,9 @@ public class ReactiveGridFsTemplate implements ReactiveGridFsOperations {
 		return publisherToUse;
 	}
 
-	private Document getMappedQuery(Document query) {
-		return queryMapper.getMappedObject(query, Optional.empty());
-	}
-
 	protected GridFSBucket getGridFs() {
 
 		MongoDatabase db = dbFactory.getMongoDatabase();
 		return bucket == null ? GridFSBuckets.create(db) : GridFSBuckets.create(db, bucket);
 	}
-
-	@Nullable
-	private Document toDocument(@Nullable Object metadata) {
-
-		Document document = null;
-
-		if (metadata != null) {
-			document = new Document();
-			converter.write(metadata, document);
-		}
-		return document;
-	}
 }

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/gridfs/ReactiveGridFsTemplateTests.java

@@ -16,10 +16,11 @@
 package org.springframework.data.mongodb.gridfs;
 
 import static org.assertj.core.api.Assertions.*;
-import static org.springframework.data.mongodb.core.query.Criteria.*;
+import static org.springframework.data.mongodb.core.query.Criteria.where;
 import static org.springframework.data.mongodb.core.query.Query.*;
 import static org.springframework.data.mongodb.gridfs.GridFsCriteria.*;
 
+import org.springframework.dao.IncorrectResultSizeDataAccessException;
 import reactor.core.publisher.Flux;
 import reactor.test.StepVerifier;
 
@@ -46,11 +47,14 @@ import com.mongodb.reactivestreams.client.gridfs.AsyncInputStream;
 import com.mongodb.reactivestreams.client.gridfs.helpers.AsyncStreamHelper;
 
 /**
+ * Integration tests for {@link ReactiveGridFsTemplate}.
+ *
  * @author Mark Paluch
+ * @author Christoph Strobl
  */
 @RunWith(SpringRunner.class)
 @ContextConfiguration("classpath:gridfs/reactive-gridfs.xml")
-public class ReactiveGridFsTemplateIntegrationTests {
+public class ReactiveGridFsTemplateTests {
 
 	Resource resource = new ClassPathResource("gridfs/gridfs.xml");
 
@@ -58,6 +62,7 @@ public class ReactiveGridFsTemplateIntegrationTests {
 
 	@Before
 	public void setUp() {
+
 		operations.delete(new Query()) //
 				.as(StepVerifier::create) //
 				.verifyComplete();
@@ -76,7 +81,8 @@ public class ReactiveGridFsTemplateIntegrationTests {
 				.as(StepVerifier::create) //
 				.assertNext(actual -> {
 					assertThat(((BsonObjectId) actual.getId()).getValue()).isEqualTo(reference);
-				}).verifyComplete();
+				}) //
+				.verifyComplete();
 	}
 
 	@Test // DATAMONGO-1855
@@ -92,7 +98,7 @@ public class ReactiveGridFsTemplateIntegrationTests {
 				.as(StepVerifier::create) //
 				.consumeNextWith(actual -> {
 					assertThat(actual.getObjectId()).isEqualTo(reference);
-				})//
+				}) //
 				.verifyComplete();
 	}
 
@@ -110,7 +116,8 @@ public class ReactiveGridFsTemplateIntegrationTests {
 				.as(StepVerifier::create) //
 				.consumeNextWith(actual -> {
 					assertThat(actual.getObjectId()).isEqualTo(reference);
-				})//
+					assertThat(actual.getMetadata()).containsEntry("version", "1.0");
+				}) //
 				.verifyComplete();
 	}
 
@@ -124,14 +131,69 @@ public class ReactiveGridFsTemplateIntegrationTests {
 
 		operations.findOne(query(where("_id").is(reference))).flatMap(operations::getResource)
 				.flatMapMany(ReactiveGridFsResource::getDownloadStream) //
-				.transform(DataBufferUtils::join).as(StepVerifier::create) //
+				.transform(DataBufferUtils::join) //
+				.as(StepVerifier::create) //
+				.consumeNextWith(dataBuffer -> {
+
+					byte[] actual = new byte[dataBuffer.readableByteCount()];
+					dataBuffer.read(actual);
+
+					assertThat(actual).isEqualTo(content);
+				}) //
+				.verifyComplete();
+	}
+
+	@Test // DATAMONGO-1855
+	public void shouldEmitFirstEntryWhenFindFirstRetrievesMoreThanOneResult() throws IOException {
+
+		AsyncInputStream upload1 = AsyncStreamHelper.toAsyncInputStream(resource.getInputStream());
+		AsyncInputStream upload2 = AsyncStreamHelper.toAsyncInputStream(new ClassPathResource("gridfs/another-resource.xml").getInputStream());
+
+		operations.store(upload1, "foo.xml", null, null).block();
+		operations.store(upload2, "foo2.xml", null, null).block();
+
+		operations.findFirst(query(where("filename").regex("foo*"))) //
+				.flatMap(operations::getResource) //
+				.as(StepVerifier::create) //
+				.expectNextCount(1) //
+				.verifyComplete();
+	}
+
+	@Test // DATAMONGO-1855
+	public void shouldEmitErrorWhenFindOneRetrievesMoreThanOneResult() throws IOException {
+
+		AsyncInputStream upload1 = AsyncStreamHelper.toAsyncInputStream(resource.getInputStream());
+		AsyncInputStream upload2 = AsyncStreamHelper.toAsyncInputStream(new ClassPathResource("gridfs/another-resource.xml").getInputStream());
+
+		operations.store(upload1, "foo.xml", null, null).block();
+		operations.store(upload2, "foo2.xml", null, null).block();
+
+		operations.findOne(query(where("filename").regex("foo*"))) //
+				.as(StepVerifier::create) //
+				.expectError(IncorrectResultSizeDataAccessException.class) //
+				.verify();
+	}
+
+	@Test // DATAMONGO-1855
+	public void getResourcesByPattern() throws IOException {
+
+		byte[] content = StreamUtils.copyToByteArray(resource.getInputStream());
+		AsyncInputStream upload = AsyncStreamHelper.toAsyncInputStream(resource.getInputStream());
+
+		operations.store(upload, "foo.xml", null, null).block();
+
+		operations.getResources("foo*") //
+				.flatMap(ReactiveGridFsResource::getDownloadStream) //
+				.transform(DataBufferUtils::join) //
+				.as(StepVerifier::create) //
 				.consumeNextWith(dataBuffer -> {
 
 					byte[] actual = new byte[dataBuffer.readableByteCount()];
 					dataBuffer.read(actual);
 
 					assertThat(actual).isEqualTo(content);
-				}).verifyComplete();
+				}) //
+				.verifyComplete();
 	}
 
 	static class Metadata {