Store file in Mongo's GridFS with ExpressJS after upload - mongodb

Question

I have started building a REST api using expressJS. I am new to node so please bear with me. I want to be able to let users upload a file directly to Mongo's GridFS using a post to the /upload route.
From what I understand in expressJS documentation the req.files.image object is available in the route after uploading, which also includes a path and filename attribute. But how can I exactly read the image data and store it into GridFS?
I have looked into gridfs-stream but I can't tie ends together. Do I first need to read the file and then use that data for the writestream pipe? Or can I just use the file object from express and use those attributes to construct a writestream? Any pointers would be appreciated!

Answer 1

Here's a simple demo:
var express = require('express');
var fs = require('fs');
var mongo = require('mongodb');
var Grid = require('gridfs-stream');
var db = new mongo.Db('test', new mongo.Server("127.0.0.1", 27017), { safe : false });
db.open(function (err) {
if (err) {
throw err;
}
var gfs = Grid(db, mongo);
var app = express();
app.use(express.bodyParser());
app.post('/upload', function(req, res) {
var tempfile = req.files.filename.path;
var origname = req.files.filename.name;
var writestream = gfs.createWriteStream({ filename: origname });
// open a stream to the temporary file created by Express...
fs.createReadStream(tempfile)
.on('end', function() {
res.send('OK');
})
.on('error', function() {
res.send('ERR');
})
// and pipe it to gfs
.pipe(writestream);
});
app.get('/download', function(req, res) {
// TODO: set proper mime type + filename, handle errors, etc...
gfs
// create a read stream from gfs...
.createReadStream({ filename: req.param('filename') })
// and pipe it to Express' response
.pipe(res);
});
app.listen(3012);
});
I use httpie to upload a file:
http --form post localhost:3012/upload filename#~/Desktop/test.png
You can check your database if the file is uploaded:
$ mongofiles list -d test
connected to: 127.0.0.1
test.png 5520
You can also download it again:
http --download get localhost:3012/download?filename=test.png