Form-Data #

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

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

Install #

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

Custom options #

You can provide custom options, such as maxDataSize:

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

var form = new FormData({ maxDataSize: 20971520 });
form.append('my_field', 'my value');
form.append('my_buffer', /* something big */);

List of available options could be found in combined-stream

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', // ... or:
    filepath: 'photos/toys/unicycle.jpg',
    contentType: 'image/jpeg',
    knownLength: 19806
  });

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

The filepath property overrides filename and may contain a relative path. This is typically used when uploading multiple files from a directory.

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);
});

Integration with other libraries #

Request #

Form submission using request:

var formData = {
  my_field: 'my_value',
  my_file: fs.createReadStream(__dirname + '/unicycle.jpg'),
};

request.post({url:'http://service.com/upload', formData: formData}, function(err, httpResponse, body) {
  if (err) {
    return console.error('upload failed:', err);
  }
  console.log('Upload successful!  Server responded with:', body);
});

For more details see request readme.

node-fetch #

You can also submit a form using node-fetch:

var form = new FormData();

form.append('a', 1);

fetch('http://example.com', { method: 'POST', body: form })
    .then(function(res) {
        return res.json();
    }).then(function(json) {
        console.log(json);
    });

Notes #

• getLengthSync() method DOESN'T calculate length for streams, use knownLength options as workaround.
• Starting version 2.x FormData has dropped support for node@0.10.x.

License #

Form-Data is released under the MIT license.