Storing data stream from POST request in GridFS, express, mongoDB, node.js

Question

I am trying to figure out how I can post an image directly to GridFS without storing it anywhere on the server as a temporary file first.

I am using Postman (chrome ext.) to post a file, and I manage to store this post as a file using:

req.pipe(fs.createWriteStream('./test.png'));

I am also able to store directly to GridFS from a readStream when the readStream is created from a file on the server. (see code)

I have the following files, saveFromReq.js which listens for the POST and basically just passes this on to the savePic.js.

saveFromReq.js:

var express = require('express');
var app = express();
var savePic = require('./savePic');
var fs = require('fs');
var GridStore = require('mongodb').GridStore;
var pic = './square.png';
var picID;



//When the following

 //var pic = fs.createReadStream('./square.png', {autoClose: true});

//is not commented out, and 'req' is replaced with 'pic' in the savePic function,
//the file square.png is stored correctly to GridFS

app.post('/picture', function(req, res){

    savePic(req, function(id){});
    res.writeHead(200, {'Content-Type': 'text' });
    res.end("Sucsess!\n");

});

app.listen(process.env.PORT || 3413);

savePic.js:

var savePic = function(req, callback){


var Db = require('mongodb').Db,
    MongoClient = require('mongodb').MongoClient,
    Server = require('mongodb').Server,
    ReplSetServers = require('mongodb').ReplSetServers,
    ObjectID = require('mongodb').ObjectID,
    Binary = require('mongodb').Binary,
    GridStore = require('mongodb').GridStore,
    Grid = require('mongodb').Grid,
    Code = require('mongodb').Code,
    BSON = require('mongodb').pure().BSON,
    assert = require('assert');
    fs = require('fs');

    //When the following 

      //req.pipe(fs.createWriteStream('./test.png'));

    //is not commented out, the correct image is stored to test.png, and 
    //the sequence after req.on("data"... starts
    //(That sequence does not start at all when this is commented out..)

var fileId = new ObjectID();
var db = new Db('testDB', new Server('localhost', 27017));
// Establish connection to db
db.open(function(err, db) {


  var gridStore = new GridStore(db, 'test', 'w');

  //open 
  gridStore.open(function(err, gridStore) {
    console.log("opened");


    req.on("data", function (data) {
        console.log("data recieved");
            gridStore.write(data, function (err, gridStore) {
                if (err) {
                    console.log("error writing file");
                }
            });
        });
     req.on("end", function () {
            gridStore.close(function (err, gridStore) {
                if (!err) {
                    console.log("The file has been stored to database.");
                    db.close();
                }
            });
        });
           req.pipe(gridStore);


      });




});
callback(fileId);
};
module.exports = savePic;

Any help would be greatly appreciated!

Solution 1

gridfs-stream makes that pretty easy:

// `gfs` is a gridfs-stream instance
app.post('/picture', function(req, res) {
  req.pipe(gfs.createWriteStream({
    filename: 'test'
  }));
  res.send("Success!");
});

Solution 2

while @robertklep's answer is correct, I would like to add something to his answer. This code shows how you can send back the stored file's metadata.

app.post('/picture', function(req, res) {
  req.pipe(gfs.createWriteStream({
    filename: 'test'
  }).on('close', function(savedFile){
    console.log('file saved', savedFile);
    return res.json({file: savedFile});
  }));
})  

Solution 3

This worked for me with mongoose:

 var gfs = Grid(mongoose.connection.db, mongoose.mongo);
    var writeStream = gfs.createWriteStream({
        filename: name,
        mode: 'w',
        content_type: 'video/mp4'
    });
    writeStream.on('close', function() {
        console.log('close event');
    });

    fs.createReadStream('uploads/' + name + '/' + name + '.mp4').pipe(writeStream);
    console.log('stream.write: ' + name + '/' + name + '.mp4');

I am struggling a couple of days with getting the video on client side browser. That is what I tried so far:

var readstream = gfs.createReadStream({
        filename: file.filename
    });

    readstream.on('data', function(data) {
        res.write(data);
        console.log(data);
    });

    readstream.on('end', function() {
        res.end();        
    });

    readstream.on('error', function (err) {
        console.log('An error occurred!', err);
        throw err;
    });

My Data on MongoDB side looks like:

db.fs.chunks.find() { "_id" : ObjectId("5757e76df14741bf0391aaca"), "files_id" : ObjectId("5757e76df14741bf0391aac8"), "n" : 0, "data" : BinData(0,"AAAAIGZ0eXBpc29....

And the contentType is 'video/mp4':

logging on browser side prints this:

Object { 0: "�", 1: "�", 2: "�", 3: " ", 4: "f", 5: "t", 6: "y", 7: "p", 8: "i", 9: "s", 85003 more… }

Could someone please save my live? I hope you do not see my post as not convenient in this place.

Comments

[hussainb]

Thanks ,This works. Also, can you please tell how to handle 'file type multiple' or multiple file controls in a form. and how to get the original file name from the post.

[JN_newbie]

@robert, I am new to gridfs. Can you please tell me what is the filename in createWriteStream. What will be the case if i want to store bytes? Should I create a new question for it?

[robertklep]

@Java_NewBie the filename is documented here. Basically, it's an (optional) identifier for the GridFS document that you're creating (so you can access that document not just through it's unique _id property but also through a human-readable string). You can make this string anything you want.

[JN_newbie]

@robertklep Thankyou robert. I am trying to use the above code to store video( bytes) which will send from the device in gridfs with your answer. but I am struggling to store it. I need an understanding. I have posted the question on the separate thread, but someone navigated to this link as duplicate.Thankyou

[vinesh]

@robertklep how can I get the details of the file stored in callback? Thanks!

[robertklep]

@vinesh you mean the meta data? See this.

[vinesh]

@robertklep Yup, I figured out to find the metadata for the stored file. your answer helped me to solve problem. Thanks :)