Form-Data

A module to create readable "multipart/form-data" streams. Can be used to submit forms and file uploads to other web applications.

The API of this module is inspired by the XMLHttpRequest-2 FormData Interface.

Install

npm install form-data

Usage

In this example we are constructing a form with 3 fields that contain a string, a buffer and a file stream.

var FormData = require('form-data');
var fs = require('fs');

var form = new FormData();
form.append('my_field', 'my value');
form.append('my_buffer', new Buffer(10));
form.append('my_file', fs.createReadStream('/foo/bar.jpg'));

Also you can use http-response stream:

var FormData = require('form-data');
var http = require('http');

var form = new FormData();

http.request('http://nodejs.org/images/logo.png', function(response) {
  form.append('my_field', 'my value');
  form.append('my_buffer', new Buffer(10));
  form.append('my_logo', response);
});

Or @mikeal's request stream:

var FormData = require('form-data');
var request = require('request');

var form = new FormData();

form.append('my_field', 'my value');
form.append('my_buffer', new Buffer(10));
form.append('my_logo', request('http://nodejs.org/images/logo.png'));

In order to submit this form to a web application, call submit(url, [callback]) method:

form.submit('http://example.org/', function(err, res) {
  // res – response object (http.IncomingMessage)  //
  res.resume(); // for node-0.10.x
});

For more advanced request manipulations submit() method returns http.ClientRequest object, or you can choose from one of the alternative submission methods.

Alternative submission methods

You can use node's http client interface:

var http = require('http');

var request = http.request({
  method: 'post',
  host: 'example.org',
  path: '/upload',
  headers: form.getHeaders()
});

form.pipe(request);

request.on('response', function(res) {
  console.log(res.statusCode);
});

Or if you would prefer the 'Content-Length' header to be set for you:

form.submit('example.org/upload', function(err, res) {
  console.log(res.statusCode);
});

To use custom headers and pre-known length in parts:

var CRLF = '\r\n';
var form = new FormData();

var options = {
  header: CRLF + '--' + form.getBoundary() + CRLF + 'X-Custom-Header: 123' + CRLF + CRLF,
  knownLength: 1
};

form.append('my_buffer', buffer, options);

form.submit('http://example.com/', function(err, res) {
  if (err) throw err;
  console.log('Done');
});

Form-Data can recognize and fetch all the required information from common types of streams (fs.readStream, http.response and mikeal's request), for some other types of streams you'd need to provide "file"-related information manually:

someModule.stream(function(err, stdout, stderr) {
  if (err) throw err;

  var form = new FormData();

  form.append('file', stdout, {
    filename: 'unicycle.jpg',
    contentType: 'image/jpg',
    knownLength: 19806
  });

  form.submit('http://example.com/', function(err, res) {
    if (err) throw err;
    console.log('Done');
  });
});

For edge cases, like POST request to URL with query string or to pass HTTP auth credentials, object can be passed to form.submit() as first parameter:

form.submit({
  host: 'example.com',
  path: '/probably.php?extra=params',
  auth: 'username:password'
}, function(err, res) {
  console.log(res.statusCode);
});

In case you need to also send custom HTTP headers with the POST request, you can use the headers key in first parameter of form.submit():

form.submit({
  host: 'example.com',
  path: '/surelynot.php',
  headers: {'x-test-header': 'test-header-value'}
}, function(err, res) {
  console.log(res.statusCode);
});

Notes

getLengthSync() method DOESN'T calculate length for streams, use knownLength options as workaround.
If it feels like FormData hangs after submit and you're on node-0.10, please check Compatibility with Older Node Versions

TODO

Add new streams (0.10) support and try really hard not to break it for 0.8.x.

License

Form-Data is licensed under the MIT license.