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) license.