How to send an object in multipart formData using request in node.js

Question

I'm trying to formulate a POST using request, but I keep getting an error anytime I try and add the to object to formData.

var fs      = require('fs');
var request = require('request');
var file    = './test/assets/test.pdf';

var opts = {
  url: 'my_service',
  method: 'POST',
  auth: { user: 'username', password: 'password' },
  json: true,
  formData: {
    front: fs.createReadStream(file),
    to: {
      name: 'joe bob',
      address_1: '123 main st',
      ...
    }
  }
};

request(opts, function(err, resp, body) {
  console.log(err, body);
});

Here is the error:

/sandbox/project/node_modules/request/node_modules/combined-stream/node_modules/delayed-stream/lib/delayed_stream.js:33
  source.on('error', function() {});
         ^
TypeError: undefined is not a function
    at Function.DelayedStream.create (/Users/me/sandbox/project/node_modules/request/node_modules/combined-stream/node_modules/delayed-stream/lib/delayed_stream.js:33:10)
    at FormData.CombinedStream.append (/Users/me/sandbox/project/node_modules/request/node_modules/combined-stream/lib/combined_stream.js:43:37)
    at FormData.append (/Users/me/sandbox/lproject/node_modules/request/node_modules/form-data/lib/form_data.js:43:3)
    at appendFormValue (/Users/me/sandbox/project/node_modules/request/request.js:466:21)
    at Request.init (/Users/me/sandbox/project/node_modules/request/request.js:477:11)
    at new Request (/Users/me/sandbox/project/node_modules/request/request.js:264:8)
    at request (/Users/me/sandbox/project/node_modules/request/index.js:50:10)
    at Object.<anonymous> (/Users/me/sandbox/project/test.js:30:1)
    at Module._compile (module.js:460:26)
    at Object.Module._extensions..js (module.js:478:10)

If I remove the to object, everything works.

Why is this - what am I doing wrong?

Answer 1

The formData attribute doesn't handle objects passed in as a value. see the documentation. A solution would be to use JSON.stringify

var fs      = require('fs');
var request = require('request');
var file    = './test/assets/test.pdf';

var toObj = {
  name: 'joe bob',
  address_1: '123 main st',
  ...
};
var opts = {
  url: 'my_service',
  method: 'POST',
  auth: { user: 'username', password: 'password' },
  json: true,
  formData: {
    front: fs.createReadStream(file),
    to: JSON.stringify(toObj)
  }
};

request(opts, function(err, resp, body) {
  console.log(err, body);
});

note: It's actually the form-data package which supports only strings. Request uses form-data. Here's their usage doc which mentions using "a string, a buffer and a file stream."