Recently i got interested in trying out the gridfs specification for storing blobs in mongodb. Also it is always fun to play around with node.js so i ended using this for my server setup.

http://tmp-space.com

The Application The server application is a running node.js application with express as its web-framework. The application exposes a series of express routes which allows the user to create spaces, upload and remove files. Each space created is created with a timer which represents the life-cycle of the newly created space. When the space timer has run out, the space is removed along with all files uploaded to that space, simply put.. its a tmp-space.

There is really no special handling in this application what so ever, it is merely a statement of how easy it actually is to store and manage files within mongodb using the gridfs implementation.

Just how easy is it? Using express we can simply upload a file by form and serverside utilize the temporary files generated to get a hold of our uploaded file data. In this example lets assume i have an open connection to mongodb using mongoose, which is passed to gridfs to instantiate the gridfs driver. In this example I am using gridfs-stream.

var gfs = Grid(conn.db, mongoose.mongo);
var tempfile = req.files.file.path;
var originalFilename = req.files.file.name;
var writestream = gfs.createWriteStream({
  filename: originalFilename
  }).on('close', function(file) {
    // will send a success to caller
    res.send(file);
  });

// open a stream to the temporary file created by Express...
fs.createReadStream(tempfile)
  .on('end', function() {
  })
  .on('error', function() {
  })
  .pipe(writestream); //pipe it to gfs writestream and store it in the database

gridfs will handle all in between logic, adding and removing file metadata and the actual file chunks in our database. The files is stored in two separate collections:

fs.files -> contains file metadata

fs.chunks -> contains file chunks

Using gridfs, we can now easily grab files and stream them back with the user request:

var readstream = gfs.createReadStream({
  _id: req.params.filesId,
});
readstream.pipe(res);

also we can simply modify the response headers depending on how we want to respond to the caller

res.setHeader('Content-type', data.contentType);
res.setHeader('Content-disposition', 'attachment; filename=' + data.filename);

have a look and try it out! http://tmp-space.com