How to get a binary stream by GridFS ObjectId with Spring Data MongoDB

Question

I can\'t figure out how to stream a binary file from GridFS with spring-data-mongodb and its GridFSTemplate when I already have the right ObjectId.

Answer 1

There is a bit mess in these types:

• GridFSFile is type from MongoDB driver
• GridFsResource is type from Spring
• ObjectId is type from BSON API

From Spring GridFsTemplate source:

public getResource(String location) {

    GridFSFile file = findOne(query(whereFilename().is(location)));
    return file != null ? new GridFsResource(file, getGridFs().openDownloadStream(location)) : null;
}

There is an ugly solution:

@Autowired
private GridFsTemplate template;

@Autowired
private GridFsOperations operations;

public InputStream loadResource(ObjectId id) throws IOException {
    GridFSFile file = template.findOne(query(where("_id").is(id)));
    GridFsResource resource = template.getResource(file.getFilename());

    GridFSFile file = operations.findOne(query(where("_id").is(id)));
    GridFsResource resource = operations.getResource(file.getFilename());
    return resource.getInputStream();
}