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.
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
arenhage 