Extend `GridFsTemplate` and its reactive variant to accept a provided `GridFSBucket` instance.

Allow to pass in a GridFSBucket from outside to avoid recreating instances on every method call.

Closes #1627
Original pull request:# 4389

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

@@ -22,6 +22,7 @@ import java.io.InputStream;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Optional;
+import java.util.function.Supplier;
 
 import org.bson.Document;
 import org.bson.types.ObjectId;
@@ -30,6 +31,7 @@ import org.springframework.data.mongodb.MongoDatabaseFactory;
 import org.springframework.data.mongodb.core.convert.MongoConverter;
 import org.springframework.data.mongodb.core.query.Query;
 import org.springframework.data.mongodb.util.BsonUtils;
+import org.springframework.data.util.Lazy;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
@@ -56,9 +58,7 @@ import com.mongodb.client.gridfs.model.GridFSUploadOptions;
  */
 public class GridFsTemplate extends GridFsOperationsSupport implements GridFsOperations, ResourcePatternResolver {
 
-	private final MongoDatabaseFactory dbFactory;
-
-	private final @Nullable String bucket;
+	private Supplier<GridFSBucket> bucketSupplier;
 
 	/**
 	 * Creates a new {@link GridFsTemplate} using the given {@link MongoDatabaseFactory} and {@link MongoConverter}.
@@ -78,13 +78,22 @@ public class GridFsTemplate extends GridFsOperationsSupport implements GridFsOpe
 	 * @param bucket can be {@literal null}.
 	 */
 	public GridFsTemplate(MongoDatabaseFactory dbFactory, MongoConverter converter, @Nullable String bucket) {
+		this(converter, Lazy.of(() -> getGridFs(dbFactory, bucket)));
+	}
 
-		super(converter);
+	/**
+	 * Creates a new {@link GridFsTemplate} using the given {@link MongoConverter} and {@link Supplier} providing the
+	 * required {@link GridFSBucket}.
+	 *
+	 * @param converter must not be {@literal null}.
+	 * @param gridFSBucket must not be {@literal null}.
+	 * @since 4.2
+	 */
+	public GridFsTemplate(MongoConverter converter, Supplier<GridFSBucket> gridFSBucket) {
 
-		Assert.notNull(dbFactory, "MongoDbFactory must not be null");
+		super(converter);
 
-		this.dbFactory = dbFactory;
-		this.bucket = bucket;
+		this.bucketSupplier = gridFSBucket;
 	}
 
 	public ObjectId store(InputStream content, @Nullable String filename, @Nullable String contentType,
@@ -142,7 +151,7 @@ public class GridFsTemplate extends GridFsOperationsSupport implements GridFsOpe
 	}
 
 	public ClassLoader getClassLoader() {
-		return dbFactory.getClass().getClassLoader();
+		return this.getClassLoader();
 	}
 
 	public GridFsResource getResource(String location) {
@@ -182,7 +191,11 @@ public class GridFsTemplate extends GridFsOperationsSupport implements GridFsOpe
 		return new GridFsResource[] { getResource(locationPattern) };
 	}
 
-	private GridFSBucket getGridFs() {
+	GridFSBucket getGridFs() {
+		return this.bucketSupplier.get();
+	}
+
+	private static GridFSBucket getGridFs(MongoDatabaseFactory dbFactory, @Nullable String bucket) {
 
 		MongoDatabase db = dbFactory.getMongoDatabase();
 		return bucket == null ? GridFSBuckets.create(db) : GridFSBuckets.create(db, bucket);

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

@@ -27,7 +27,6 @@ import org.bson.BsonValue;
 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;
@@ -37,6 +36,7 @@ import org.springframework.data.mongodb.core.convert.MongoConverter;
 import org.springframework.data.mongodb.core.query.Query;
 import org.springframework.data.mongodb.core.query.SerializationUtils;
 import org.springframework.data.mongodb.util.BsonUtils;
+import org.springframework.data.util.Lazy;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
@@ -61,9 +61,8 @@ import com.mongodb.reactivestreams.client.gridfs.GridFSUploadPublisher;
  */
 public class ReactiveGridFsTemplate extends GridFsOperationsSupport implements ReactiveGridFsOperations {
 
-	private final ReactiveMongoDatabaseFactory dbFactory;
 	private final DataBufferFactory dataBufferFactory;
-	private final @Nullable String bucket;
+	private Mono<GridFSBucket> bucketSupplier;
 
 	/**
 	 * Creates a new {@link ReactiveGridFsTemplate} using the given {@link ReactiveMongoDatabaseFactory} and
@@ -100,15 +99,27 @@ public class ReactiveGridFsTemplate extends GridFsOperationsSupport implements R
 	 */
 	public ReactiveGridFsTemplate(DataBufferFactory dataBufferFactory, ReactiveMongoDatabaseFactory dbFactory,
 			MongoConverter converter, @Nullable String bucket) {
+		this(converter, Mono.defer(Lazy.of(() -> doGetBucket(dbFactory, bucket))), dataBufferFactory);
+	}
+
+	/**
+	 * Creates a new {@link ReactiveGridFsTemplate} using the given {@link MongoConverter}, {@link Mono} emitting a
+	 * {@link ReactiveMongoDatabaseFactory} and {@link DataBufferFactory}.
+	 * 
+	 * @param converter must not be {@literal null}.
+	 * @param gridFSBucket must not be {@literal null}.
+	 * @param dataBufferFactory must not be {@literal null}.
+	 * @since 4.2
+	 */
+	public ReactiveGridFsTemplate(MongoConverter converter, Mono<GridFSBucket> gridFSBucket,
+			DataBufferFactory dataBufferFactory) {
 
 		super(converter);
 
 		Assert.notNull(dataBufferFactory, "DataBufferFactory must not be null");
-		Assert.notNull(dbFactory, "ReactiveMongoDatabaseFactory must not be null");
 
+		this.bucketSupplier = gridFSBucket;
 		this.dataBufferFactory = dataBufferFactory;
-		this.dbFactory = dbFactory;
-		this.bucket = bucket;
 	}
 
 	@Override
@@ -247,11 +258,15 @@ public class ReactiveGridFsTemplate extends GridFsOperationsSupport implements R
 		return doGetBucket().flatMapMany(callback::doInBucket);
 	}
 
-	protected Mono<GridFSBucket> doGetBucket() {
+	static Mono<GridFSBucket> doGetBucket(ReactiveMongoDatabaseFactory dbFactory, @Nullable String bucket) {
 		return dbFactory.getMongoDatabase()
 				.map(db -> bucket == null ? GridFSBuckets.create(db) : GridFSBuckets.create(db, bucket));
 	}
 
+	protected Mono<GridFSBucket> doGetBucket() {
+		return bucketSupplier;
+	}
+
 	/**
 	 * @param <T>
 	 * @author Mathieu Ouellet

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/config/MongoNamespaceTests.java

@@ -20,6 +20,11 @@ import static org.springframework.test.util.ReflectionTestUtils.*;
 
 import javax.net.ssl.SSLSocketFactory;
 
+import java.util.function.Supplier;
+
+import com.mongodb.client.MongoCollection;
+import com.mongodb.client.gridfs.GridFSBucket;
+import com.mongodb.client.gridfs.model.GridFSFile;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.springframework.beans.factory.annotation.Autowired;
@@ -168,8 +173,12 @@ public class MongoNamespaceTests {
 		assertThat(ctx.containsBean("gridFsTemplate")).isTrue();
 		GridFsOperations operations = (GridFsOperations) ctx.getBean("gridFsTemplate");
 
-		MongoDatabaseFactory dbf = (MongoDatabaseFactory) getField(operations, "dbFactory");
-		assertThat(getField(dbf, "databaseName")).isEqualTo("database");
+		Supplier<GridFSBucket> gridFSBucketSupplier = (Supplier<GridFSBucket>) getField(operations, "bucketSupplier");
+		GridFSBucket gfsBucket = gridFSBucketSupplier.get();
+		assertThat(gfsBucket.getBucketName()).isEqualTo("fs"); // fs is the default
+
+		MongoCollection<GridFSFile> filesCollection = (MongoCollection<GridFSFile>) getField(gfsBucket, "filesCollection");
+		assertThat(filesCollection.getNamespace().getDatabaseName()).isEqualTo("database");
 
 		MongoConverter converter = (MongoConverter) getField(operations, "converter");
 		assertThat(converter).isNotNull();
@@ -181,9 +190,12 @@ public class MongoNamespaceTests {
 		assertThat(ctx.containsBean("secondGridFsTemplate")).isTrue();
 		GridFsOperations operations = (GridFsOperations) ctx.getBean("secondGridFsTemplate");
 
-		MongoDatabaseFactory dbf = (MongoDatabaseFactory) getField(operations, "dbFactory");
-		assertThat(getField(dbf, "databaseName")).isEqualTo("database");
-		assertThat(getField(operations, "bucket")).isEqualTo(null);
+		Supplier<GridFSBucket> gridFSBucketSupplier = (Supplier<GridFSBucket>) getField(operations, "bucketSupplier");
+		GridFSBucket gfsBucket = gridFSBucketSupplier.get();
+		assertThat(gfsBucket.getBucketName()).isEqualTo("fs"); // fs is the default
+
+		MongoCollection<GridFSFile> filesCollection = (MongoCollection<GridFSFile>) getField(gfsBucket, "filesCollection");
+		assertThat(filesCollection.getNamespace().getDatabaseName()).isEqualTo("database");
 
 		MongoConverter converter = (MongoConverter) getField(operations, "converter");
 		assertThat(converter).isNotNull();
@@ -195,9 +207,12 @@ public class MongoNamespaceTests {
 		assertThat(ctx.containsBean("thirdGridFsTemplate")).isTrue();
 		GridFsOperations operations = (GridFsOperations) ctx.getBean("thirdGridFsTemplate");
 
-		MongoDatabaseFactory dbf = (MongoDatabaseFactory) getField(operations, "dbFactory");
-		assertThat(getField(dbf, "databaseName")).isEqualTo("database");
-		assertThat(getField(operations, "bucket")).isEqualTo("bucketString");
+		Supplier<GridFSBucket> gridFSBucketSupplier = (Supplier<GridFSBucket>) getField(operations, "bucketSupplier");
+		GridFSBucket gfsBucket = gridFSBucketSupplier.get();
+		assertThat(gfsBucket.getBucketName()).isEqualTo("bucketString"); // fs is the default
+
+		MongoCollection<GridFSFile> filesCollection = (MongoCollection<GridFSFile>) getField(gfsBucket, "filesCollection");
+		assertThat(filesCollection.getNamespace().getDatabaseName()).isEqualTo("database");
 
 		MongoConverter converter = (MongoConverter) getField(operations, "converter");
 		assertThat(converter).isNotNull();