how to download a file saved in gridFS using nodeJS

I need to download a resume from GridFS, below is the code ive written to do it, but this seems to not give me a physical file for download, this is used to reading the contents. How can i download the file?

exports.getFileById = function(req, res){
var conn = mongoose.connection;
var gfs = Grid(conn.db, mongoose.mongo);
var id = req.params.ID;
gfs.exist({_id: id,root: 'resume'}, function (err, found) {
    if (err) return handleError(err);
    if (!found)
        return res.send('Error on the database looking for the file.');
    gfs.createReadStream({_id: id,root: 'resume'}).pipe(res);
});
};

Hope this helps!

exports.downloadResume = function(req, res){
var conn = mongoose.connection;
var gfs = Grid(conn.db, mongoose.mongo);
gfs.findOne({ _id: <resumeId>, root: <collectionName> }, function (err, file) {
    if (err) {
        return res.status(400).send(err);
    }
    else if (!file) {
        return res.status(404).send('Error on the database looking for the file.');
    }

    res.set('Content-Type', file.contentType);
    res.set('Content-Disposition', 'attachment; filename="' + file.filename + '"');

    var readstream = gfs.createReadStream({
      _id: <resumeId>,
      root: '<collectionName>'
    });
    
    readstream.on("error", function(err) { 
        res.end();
    });
    readstream.pipe(res);
  });
};