Support decoding legacy files that don't contain filenames

JAVA-2546

Author: rozza

driver-async/src/test/functional/com/mongodb/async/client/gridfs/GridFSBucketSmokeTestSpecification.groovy

@@ -44,6 +44,7 @@ import static com.mongodb.async.client.TestHelper.runSlow
 import static com.mongodb.async.client.gridfs.helpers.AsyncStreamHelper.toAsyncInputStream
 import static com.mongodb.async.client.gridfs.helpers.AsyncStreamHelper.toAsyncOutputStream
 import static com.mongodb.client.model.Filters.eq
+import static com.mongodb.client.model.Updates.unset
 import static org.bson.codecs.configuration.CodecRegistries.fromCodecs
 import static org.bson.codecs.configuration.CodecRegistries.fromRegistries
 
@@ -511,5 +512,47 @@ class GridFSBucketSmokeTestSpecification extends FunctionalSpecification {
         then:
         fileAsDocument.getDocument('metadata').getBinary('uuid').getType() == 4 as byte
     }
+
+    @Unroll
+    def 'should handle missing file name data when downloading #description'() {
+        given:
+        def content = multiChunkString
+        def contentBytes = content as byte[]
+        ObjectId fileId
+
+        when:
+        if (direct) {
+            fileId = run(gridFSBucket.&uploadFromStream, 'myFile', toAsyncInputStream(content.getBytes()));
+        } else {
+            def outputStream = gridFSBucket.openUploadStream('myFile')
+            run(outputStream.&write, ByteBuffer.wrap(contentBytes))
+            run(outputStream.&close)
+            fileId = outputStream.getObjectId()
+        }
+
+        then:
+        run(filesCollection.&count) == 1
+
+        when:
+        // Remove filename
+        run(filesCollection.&updateOne, eq('_id', fileId), unset('filename'))
+
+        def byteBuffer = ByteBuffer.allocate(contentBytes.length)
+        if (direct) {
+            run(gridFSBucket.openDownloadStream(fileId).&read, byteBuffer)
+        } else {
+            def outputStream = toAsyncOutputStream(byteBuffer)
+            run(gridFSBucket.&downloadToStream, fileId, outputStream)
+            run(outputStream.&close)
+        }
+
+        then:
+        byteBuffer.array() == contentBytes
+
+        where:
+        description | direct
+        'directly'  | true
+        'a stream'  | false
+    }
 }
 

driver-core/src/main/com/mongodb/client/gridfs/codecs/GridFSFileCodec.java

@@ -65,7 +65,7 @@ public GridFSFile decode(final BsonReader reader, final DecoderContext decoderCo
         BsonDocument bsonDocument = bsonDocumentCodec.decode(reader, decoderContext);
 
         BsonValue id = bsonDocument.get("_id");
-        String filename = bsonDocument.getString("filename").getValue();
+        String filename = bsonDocument.get("filename", new BsonString("")).asString().getValue();
         long length = bsonDocument.getNumber("length").longValue();
         int chunkSize = bsonDocument.getNumber("chunkSize").intValue();
         Date uploadDate = new Date(bsonDocument.getDateTime("uploadDate").getValue());

driver/src/test/functional/com/mongodb/client/gridfs/GridFSBucketSmokeTestSpecification.groovy

@@ -35,6 +35,8 @@ import java.security.MessageDigest
 
 import static com.mongodb.Fixture.getDefaultDatabaseName
 import static com.mongodb.Fixture.getMongoClient
+import static com.mongodb.client.model.Filters.eq
+import static com.mongodb.client.model.Updates.unset
 import static org.bson.codecs.configuration.CodecRegistries.fromCodecs
 import static org.bson.codecs.configuration.CodecRegistries.fromRegistries
 
@@ -557,4 +559,47 @@ class GridFSBucketSmokeTestSpecification extends FunctionalSpecification {
         then:
         gridFSContentBytes == contentBytes
     }
+
+    @Unroll
+    def 'should handle missing file name data when downloading #description'() {
+        given:
+        def content = multiChunkString
+        def contentBytes = content as byte[]
+        ObjectId fileId
+        byte[] gridFSContentBytes
+
+        when:
+        if (direct) {
+            fileId = gridFSBucket.uploadFromStream('myFile', new ByteArrayInputStream(contentBytes));
+        } else {
+            def outputStream = gridFSBucket.openUploadStream('myFile')
+            outputStream.write(contentBytes)
+            outputStream.close()
+            fileId = outputStream.getObjectId()
+        }
+
+        then:
+        filesCollection.count() == 1
+
+        when:
+        // Remove filename
+        filesCollection.updateOne(eq('_id', fileId), unset('filename'))
+
+        if (direct) {
+            gridFSContentBytes = gridFSBucket.openDownloadStream(fileId).getBytes()
+        } else {
+            def outputStream = new ByteArrayOutputStream(contentBytes.length)
+            gridFSBucket.downloadToStream(fileId, outputStream)
+            outputStream.close()
+            gridFSContentBytes = outputStream.toByteArray()
+        }
+
+        then:
+        gridFSContentBytes == contentBytes
+
+        where:
+        description | direct
+        'directly'  | true
+        'a stream'  | false
+    }
 }