ExpressJS File Uploading – GridFS – MongoDB

In this blog post we will see how to handle multipart data/file uploading with expressjs. Save files to mongodb using GridFS and rending files.

To handle file uploads in express, i will use the library located at https://github.com/expressjs/multer

$ npm install multer --save

In your express app.js file

var app = express();
app.use('/uploads', express.static(__dirname + "/uploads"));
app.use(multer({dest: './uploads/'}))

The above code catches all multipart data, fileuploads automatically and stores the file to ‘uploads/’ folder. So its super easy. So basically if you have a form tag, with its action pointed to a express route. Fileupload server handling is taken care automatically and all file move to ‘uploads’ folder.

Now let’s see how to save uploaded file to mongodb. Detailed explanation of using gridfs here

Suppose the file upload URL is http://127.0.0.1:3000/upload

var fs = require('fs');
var mongoose = require('mongoose');
router.all('/upload',function(req,res){
     var dirname = require('path').dirname(__dirname);
     var filename = req.files.file.name;
     var path = req.files.file.path;
     var type = req.files.file.mimetype;
     
     var read_stream =  fs.createReadStream(dirname + '/' + path);

     var conn = req.conn;
     var Grid = require('gridfs-stream');
     Grid.mongo = mongoose.mongo;

     var gfs = Grid(conn.db);
     
     var writestream = gfs.createWriteStream({
        filename: filename 
    });
     read_stream.pipe(writestream);
       
});

Now let’s see how to view image file uploaded in mongo

If URL to view files is http://127.0.0.1:3000/file/mongo_id


router.get('/file/:id',function(req,res){
      var pic_id = req.param('id');
      var gfs = req.gfs;

       gfs.files.find({filename: pic_id}).toArray(function (err, files) {

        if (err) {
            res.json(err);
        }
        if (files.length > 0) {
            var mime = 'image/jpeg';
            res.set('Content-Type', mime);
            var read_stream = gfs.createReadStream({filename: pic_id});
            read_stream.pipe(res);
        } else {
            res.json('File Not Found');
        }
    });
});