Send file in memory to API from Node Express

Question

I've an API in Node and Express which is receiving a file from a the client (Postman in development) and I use multer to get the file in memory like this:

router.post('/api/v1/upload', contrl.upload, contrl.uploadFile);

and then in my controller:

exports upload = multer({ storage: multer.memoryStorage() }).single('file');

Now I can access the file with req.file.buffer, but then I want to send this same file to another API. I'm using request-promise-native so this would be something like this:

const rp = require('request-promise-native')

exports.uploadFile = (req, res) => {

  const options = {
    method: 'POST',
    uri: `${uri}`,
    form: {
      file: req.file.buffer
    }
  }

  rp(options)
    .then(parsedBody => {
      return res.status(201).send(parsedBody);
    })
    .catch(err => res.status(400).send(err));
}

I removed some other params for simplicity, but this is not working, probably because Node doesn´t know how to handle the info inside req.file.buffer.

EDIT. Ok after some tests I tried to make this work with a real file instead of using multer memoryStorage. So I got this:

exports upload = multer({ dest: 'uploads/' }).single('file');

to save the file to disk, and then

const request = require('request')

exports.uploadFile = (req, res) => {

  const formData = {
    file: fs.createReadStream('uploads/' + req.file.filename)
  }
  const options = {
    url: `${uri}`
    formData
  }

  request.post(options, (err, response, body) => {
    if (err) return res.status(400).send(err);
    return res.status(201).send(response);
  });
}

And it works! But then when I change to memoryStorage in multer and I use file: req.file.buffer instead, it does not work.

EDIT2: I also tried to send the file as a stream when in memory, so I tried this

const bufferStream = new stream.PassThrough();
bufferStream.end(req.file.buffer);

and then passing it in the formData with file: bufferStream but also not working.

How can I achieve this? Thanks

Fidel Perez · Accepted Answer · 2021-04-20 13:19:34Z

3

I had the same problem a few times and always end up with a bad solution. thank you all for this post. Here is my solution with aixios in case someone can use it

//First use form-data
const FormData = require('form-data') ;
//use axios
const axios = require('axios') ;


//Note is very important passing contentType and filename 
//options
let form = new FormData() ;
//consider req.file is the file coming from multer
form.append('file',req.file.buffer,{
     contentType:req.file.mimetype,
     filename:req.file.originalname
  }) ;


//now do a post request with axios
// personally I like the use of async-await for promises but
//then() catch() will work just fine
let response = await axios.post('API_URL', form, {
  headers: form.getHeaders() 
});
// whatever you need with response ex.
console.log(response.data)

answered Apr 20, 2021 at 13:19

Fidel Perez

311 bronze badge

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Comments

obadogg · Accepted Answer · 2017-11-16 16:14:21Z

I recently encountered a similar situation，My process:web to node to PHP.I use "multer" and "request" resolve this problem and i don't use real file.

    const multer  = require('multer')
    const upload = multer();
    const request = require('request');

    router.post('/upload', upload.single('img'),(req,res,next) => {

        let formData = {
            'quality':80,
            //file field need set options 'contentType' and 'filename' for formData
            'file':{
                value:req.file.buffer,
                options:{
                    contentType:req.file.mimetype,
                    filename:req.file.originalname
                }
            }
        }    
       request.post({
             url:''/**uploadurl*/,
             formData
       },function(err,response,body){res.send(body)})
    })

Julien Klepatch · Accepted Answer · 2017-05-30 08:21:29Z

0

const rp = require('request-promise-native')

exports.uploadFile = (req, res) => {

  const options = {
    method: 'POST',
    uri: `${uri}`,
    formData: {
      file: req.file.buffer
    }
  }

  rp(options)
    .then(parsedBody => {
      return res.status(201).send(parsedBody);
    })
    .catch(err => res.status(400).send(err));
}

edited May 30, 2017 at 8:21

answered May 30, 2017 at 7:42

Julien Klepatch

3481 silver badge5 bronze badges

7 Comments

David Over a year ago

I get an error. Do I need some special header or something? In the response I can see "error": "Bad Request", "options": { "method":"POST", "uri": "....", "file": "cHJ1ZWJh=="}

Julien Klepatch Over a year ago

check the API that you are calling. They probably expect the request to be done in a certain way.

David Over a year ago

Nothing special. The API works fine if I use Postman and send a POST request with form-data and the file as File. When I inspect the request payload I get Content-Type: text/plain for the file, but if I use the above mechanism it's a binary object, so I'm guessing something is not quite right and the API does not know how to interpret this

Julien Klepatch Over a year ago

When you use base64 encoding you are sending plain text, not binary data. If you dont use base64 encoding what happen?

David Over a year ago

If I don´t use base64 then this is what I see in the request header "form": { ... "file": { "type": "Buffer", "data": [ 112, 114, 117, 101,... ]}}" and the same error from the API

|

ponury-kostek · Accepted Answer · 2017-06-06 12:32:19Z

0

This should solve your problem

const http = require('http');
exports.uploadFile = (req, res) => {
    // create new request to reupload file
    const request = http.request({  
        port : 80,
        hostname : '127.0.0.1',
        method : 'POST',
        path : '/'
    });
    let result = '';
    // grab response from new request
    request.on('data', (chunk) => {
        result += chunk;
    });
    // resend response from new request
    request.on('end', () => {
        res.status(201).end(result);
    });
    // resend error from new request
    request.on('error', (err) => {
        res.status(400).end(err);
    });
    // pipe your file to new request
    req.file.stream.pipe(request);
};

answered Jun 6, 2017 at 12:32

ponury-kostek

8,0835 gold badges27 silver badges33 bronze badges

Comments

Anup Nair · Accepted Answer · 2017-09-06 18:54:36Z

0

Use Node Memory Streams https://www.npmjs.com/package/memory-streams

var streams = require('memory-streams')
  , fs      = require('fs');

// Pipe  
var reader = fs.createReadStream('index.js');
var writer = new streams.WritableStream();
reader.pipe(writer);
reader.on('readable', function() {

  // Output the content as a string 
  console.log(writer.toString());

  // Output the content as a Buffer 
  console.log(writer.toBuffer());
});

answered Sep 6, 2017 at 18:54

Anup Nair

111 bronze badge

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