# Form-Data [](https://www.npmjs.com/package/form-data) [](https://gitter.im/form-data/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][xhr2-fd].
[xhr2-fd]: http://dev.w3.org/2006/webapi/XMLHttpRequest-2/Overview.html#the-formdata-interface
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## 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.
``` javascript
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:
``` javascript
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](https://github.com/request/request) stream:
``` javascript
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:
``` javascript
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`:
``` javascript
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](https://github.com/felixge/node-combined-stream/blob/master/lib/combined_stream.js#L7-L15)
### Alternative submission methods
You can use node's http client interface:
``` javascript
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:
``` javascript
form.submit('example.org/upload', function(err, res) {
console.log(res.statusCode);
});
```
To use custom headers and pre-known length in parts:
``` javascript
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:
``` javascript
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](https://wicg.github.io/entries-api/#dom-htmlinputelement-webkitdirectory).
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:
``` javascript
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()`:
``` javascript
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](https://github.com/request/request):
```javascript
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](https://github.com/request/request#multipartform-data-multipart-form-uploads).
#### node-fetch
You can also submit a form using [node-fetch](https://github.com/bitinn/node-fetch):
```javascript
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.
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