DATAMONGO-1813 - Add GridFsOperations.getResource(GridFSFile).

We now provide GridFsOperations.getResource(GridFSFile) to create GridFsResource without a database lookup. This allows direct creation of GridFsResource for GridFSFile.

Original pull request: #543.

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

@@ -34,6 +34,7 @@ import com.mongodb.client.gridfs.GridFSFindIterable;
  * @author Thomas Darimont
  * @author Martin Baumgartner
  * @author Christoph Strobl
+ * @author Hartmut Lang
  */
 public interface GridFsOperations extends ResourcePatternResolver {
 
@@ -157,6 +158,13 @@ public interface GridFsOperations extends ResourcePatternResolver {
 	 */
 	GridFsResource getResource(String filename);
 
+	/**
+	 * Returns the {@link GridFsResource} for a {@link com.mongodb.client.gridfs.model.GridFSFile}.
+	 * @param file must not be {@literal null}.
+	 * @return the resource for the file.
+	 */
+	GridFsResource getResource(com.mongodb.client.gridfs.model.GridFSFile file);
+
 	/**
 	 * Returns all {@link GridFsResource}s matching the given file name pattern.
 	 *

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

@@ -51,6 +51,7 @@ import com.mongodb.client.gridfs.model.GridFSUploadOptions;
  * @author Martin Baumgartner
  * @author Christoph Strobl
  * @author Mark Paluch
+ * @author Hartmut Lang
  */
 public class GridFsTemplate implements GridFsOperations, ResourcePatternResolver {
 
@@ -228,7 +229,16 @@ public class GridFsTemplate implements GridFsOperations, ResourcePatternResolver
 	public GridFsResource getResource(String location) {
 
 		GridFSFile file = findOne(query(whereFilename().is(location)));
-		return file != null ? new GridFsResource(file, getGridFs().openDownloadStream(location)) : null;
+		return file != null ? getResource(file) : null;
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.gridfs.GridFsOperations#getResource(com.mongodb.client.gridfs.model.GridFSFile)
+	 */
+	public GridFsResource getResource(GridFSFile file) {
+
+		return new GridFsResource(file, getGridFs().openDownloadStream(file.getFilename()));
 	}
 
 	/*

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

@@ -42,6 +42,7 @@ import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
 
 import com.mongodb.MongoGridFSException;
 import com.mongodb.client.gridfs.GridFSFindIterable;
+import com.mongodb.client.gridfs.model.GridFSFile;
 
 /**
  * Integration tests for {@link GridFsTemplate}.
@@ -50,6 +51,7 @@ import com.mongodb.client.gridfs.GridFSFindIterable;
  * @author Philipp Schneider
  * @author Thomas Darimont
  * @author Martin Baumgartner
+ * @author Hartmut Lang
  */
 @RunWith(SpringJUnit4ClassRunner.class)
 @ContextConfiguration("classpath:gridfs/gridfs.xml")
@@ -225,6 +227,20 @@ public class GridFsTemplateIntegrationTests {
 		assertThatThrownBy(() -> result.getContentType()).isInstanceOf(MongoGridFSException.class);
 	}
 
+	@Test // DATAMONGO-1813
+	public void convertFileToResource() throws IOException {
+
+		Document metadata = new Document("key", "value");
+		ObjectId reference = operations.store(resource.getInputStream(), "foobar", metadata);
+
+		List<com.mongodb.client.gridfs.model.GridFSFile> files = new ArrayList<com.mongodb.client.gridfs.model.GridFSFile>();
+		GridFSFile file = operations.findOne(query(whereMetaData("key").is("value")));
+		GridFsResource result = operations.getResource(file);
+
+		assertThat(result.contentLength()).isEqualTo(resource.contentLength());
+		assertThat(((BsonObjectId) result.getId()).getValue()).isEqualTo(reference);
+	}
+
 	class Metadata {
 		String version;
 	}