A Node.js module for parsing form data, especially file uploads.
If you have any how-to kind of questions, please read the Contributing
Guide and Code of Conduct
documents.
For bugs reports and feature requests, please create an
issue or ping @tunnckoCore / @3a1FcBx0
at Twitter.
![Minimum Required Nodejs][nodejs-img]
This project is semantically versioned and available as
part of the Tidelift Subscription for professional grade
assurances, enhanced support and security.
Learn more.
The maintainers of formidable and thousands of other packages are working
with Tidelift to deliver commercial support and maintenance for the Open Source
dependencies you use to build your applications. Save time, reduce risk, and
improve code health, while paying the maintainers of the exact dependencies you
use.
![][npmv-url] [![]npm-monthly-img][npmv-url] [![]npm-yearly-img][npmv-url] [![]npm-alltime-img]npmv-url
Check VERSION NOTES for more information on v1, v2, and v3 plans, NPM dist-tags and branches.
This module was initially developed by
@felixge for
Transloadit, a service focused on uploading and
encoding images and videos. It has been battle-tested against hundreds of GBs of
file uploads from a large variety of clients and is considered production-ready
and is used in production for years.
Currently, we are few maintainers trying to deal with it. :) More contributors
are always welcome! :heart: Jump on
issue #412 which is
closed, but if you are interested we can discuss it and add you after strict
rules, like enabling Two-Factor Auth in your npm and GitHub accounts.
options.fileWriteStreamHandler)This project requires Node.js >= 10.13. Install it using
yarn or npm.
We highly
recommend to use Yarn when you think to contribute to this project.
This is a low-level package, and if you're using a high-level framework it may
already be included. Check the examples below and the examples/ folder.
# v2
npm install formidable
npm install formidable@latest
npm install formidable@v2
# or v3
npm install formidable@v3
Note: In near future v3 will be published on the latest NPM dist-tag. Future not ready releases will continue to be published on canary dist-tag.
For more examples look at the examples/ directory.
Parse an incoming file upload, with the
Node.js's built-in http module.
const http = require('http');
const formidable = require('formidable');
const server = http.createServer((req, res) => {
if (req.url === '/api/upload' && req.method.toLowerCase() === 'post') {
// parse a file upload
const form = formidable({ multiples: true });
form.parse(req, (err, fields, files) => {
if (err) {
res.writeHead(err.httpCode || 400, { 'Content-Type': 'text/plain' });
res.end(String(err));
return;
}
res.writeHead(200, { 'Content-Type': 'application/json' });
res.end(JSON.stringify({ fields, files }, null, 2));
});
return;
}
// show a file upload form
res.writeHead(200, { 'Content-Type': 'text/html' });
res.end(`
<h2>With Node.js <code>"http"</code> module</h2>
<form action="/api/upload" enctype="multipart/form-data" method="post">
<div>Text field title: <input type="text" name="title" /></div>
<div>File: <input type="file" name="multipleFiles" multiple="multiple" /></div>
<input type="submit" value="Upload" />
</form>
`);
});
server.listen(8080, () => {
console.log('Server listening on http://localhost:8080/ ...');
});
There are multiple variants to do this, but Formidable just need Node.js Request
stream, so something like the following example should work just fine, without
any third-party Express.js middleware.
Or try the
examples/with-express.js
const express = require('express');
const formidable = require('formidable');
const app = express();
app.get('/', (req, res) => {
res.send(`
<h2>With <code>"express"</code> npm package</h2>
<form action="/api/upload" enctype="multipart/form-data" method="post">
<div>Text field title: <input type="text" name="title" /></div>
<div>File: <input type="file" name="someExpressFiles" multiple="multiple" /></div>
<input type="submit" value="Upload" />
</form>
`);
});
app.post('/api/upload', (req, res, next) => {
const form = formidable({ multiples: true });
form.parse(req, (err, fields, files) => {
if (err) {
next(err);
return;
}
res.json({ fields, files });
});
});
app.listen(3000, () => {
console.log('Server listening on http://localhost:3000 ...');
});
Of course, with Koa v1, v2 or future v3 the things
are very similar. You can use formidable manually as shown below or through
the koa-better-body package which is
using formidable under the hood and support more features and different
request bodies, check its documentation for more info.
Note: this example is assuming Koa v2. Be aware that you should pass ctx.req
which is Node.js's Request, and NOT the ctx.request which is Koa's Request
object - there is a difference.
const Koa = require('koa');
const formidable = require('formidable');
const app = new Koa();
app.on('error', (err) => {
console.error('server error', err);
});
app.use(async (ctx, next) => {
if (ctx.url === '/api/upload' && ctx.method.toLowerCase() === 'post') {
const form = formidable({ multiples: true });
// not very elegant, but that's for now if you don't want to use `koa-better-body`
// or other middlewares.
await new Promise((resolve, reject) => {
form.parse(ctx.req, (err, fields, files) => {
if (err) {
reject(err);
return;
}
ctx.set('Content-Type', 'application/json');
ctx.status = 200;
ctx.state = { fields, files };
ctx.body = JSON.stringify(ctx.state, null, 2);
resolve();
});
});
await next();
return;
}
// show a file upload form
ctx.set('Content-Type', 'text/html');
ctx.status = 200;
ctx.body = `
<h2>With <code>"koa"</code> npm package</h2>
<form action="/api/upload" enctype="multipart/form-data" method="post">
<div>Text field title: <input type="text" name="title" /></div>
<div>File: <input type="file" name="koaFiles" multiple="multiple" /></div>
<input type="submit" value="Upload" />
</form>
`;
});
app.use((ctx) => {
console.log('The next middleware is called');
console.log('Results:', ctx.state);
});
app.listen(3000, () => {
console.log('Server listening on http://localhost:3000 ...');
});
The benchmark is quite old, from the old codebase. But maybe quite true though.
Previously the numbers was around ~500 mb/sec. Currently with moving to the new
Node.js Streams API it's faster. You can clearly see the differences between the
Node versions.
Note: a lot better benchmarking could and should be done in future.
Benchmarked on 8GB RAM, Xeon X3440 (2.53 GHz, 4 cores, 8 threads)
~/github/node-formidable master
❯ nve --parallel 8 10 12 13 node benchmark/bench-multipart-parser.js
⬢ Node 8
1261.08 mb/sec
⬢ Node 10
1113.04 mb/sec
⬢ Node 12
2107.00 mb/sec
⬢ Node 13
2566.42 mb/sec
All shown are equivalent.
Please pass options to the function/constructor, not by assigning
them to the instance form
const formidable = require('formidable');
const form = formidable(options);
// or
const { formidable } = require('formidable');
const form = formidable(options);
// or
const { IncomingForm } = require('formidable');
const form = new IncomingForm(options);
// or
const { Formidable } = require('formidable');
const form = new Formidable(options);
See it's defaults in src/Formidable.js DEFAULT_OPTIONS
(the DEFAULT_OPTIONS constant).
options.encoding {string} - default 'utf-8'; sets encoding foroptions.uploadDir {string} - default os.tmpdir(); the directory forfs.rename().options.keepExtensions {boolean} - default false; to include theoptions.allowEmptyFiles {boolean} - default true; allow upload emptyoptions.minFileSize {number} - default 1 (1byte); the minium size ofoptions.maxFileSize {number} - default 200 * 1024 * 1024 (200mb);options.maxFields {number} - default 1000; limit the number of fields, set 0 for unlimitedoptions.maxFieldsSize {number} - default 20 * 1024 * 1024 (20mb);options.hashAlgorithm {string | false} - default false; include checksums calculatedoptions.fileWriteStreamHandler {function} - default null, which byoptions.multiples {boolean} - default false; when you call the.parse method, the files argument (of the callback) will contain arrays ofmultiplefields argument will contain arrays of values foroptions.filename {function} - default undefined Use it to controloptions.filter {function} - default function that always returns true.
Use it to filter files before they are uploaded. Must return a boolean.
options.filename {function} function (name, ext, part, form) -> stringNote: If this size of combined fields, or size of some file is exceeded, an'error' event is fired.
// The amount of bytes received for this form so far.
form.bytesReceived;
// The expected number of bytes in this form.
form.bytesExpected;
options.filter {function} function ({name, originalFilename, mimetype}) -> booleanNote: use an outside variable to cancel all uploads upon the first error
const options = {
filter: function ({name, originalFilename, mimetype}) {
// keep only images
return mimetype && mimetype.includes("image");
}
};
Parses an incoming Node.js request containing form data. If callback is
provided, all fields and files are collected and passed to the callback.
const formidable = require('formidable');
const form = formidable({ multiples: true, uploadDir: __dirname });
form.parse(req, (err, fields, files) => {
console.log('fields:', fields);
console.log('files:', files);
});
You may overwrite this method if you are interested in directly accessing the
multipart stream. Doing so will disable any 'field' / 'file' events
processing which would occur otherwise, making you fully responsible for
handling the processing.
About uploadDir, given the following directory structure project-name ├── src │ └── server.js │ └── uploads └── image.jpg
__dirname would be the same directory as the source file itself (src)
`${__dirname}/../uploads`
to put files in uploads.
Omitting __dirname would make the path relative to the current working directory. This would be the same if server.js is launched from src but not project-name.
null will use default which is os.tmpdir()
Note: If the directory does not exist, the uploaded files are silently discarded. To make sure it exists:
import {createNecessaryDirectoriesSync} from "filesac";
const uploadPath = `${__dirname}/../uploads`;
createNecessaryDirectoriesSync(`${uploadPath}/x`);
In the example below, we listen on couple of events and direct them to thedata listener, so you can do whatever you choose there, based on whether its
before the file been emitted, the header value, the header name, on field, on
file and etc.
Or the other way could be to just override the form.onPart as it's shown a bit
later.
form.once('error', console.error);
form.on('fileBegin', (formname, file) => {
form.emit('data', { name: 'fileBegin', formname, value: file });
});
form.on('file', (formname, file) => {
form.emit('data', { name: 'file', formname, value: file });
});
form.on('field', (fieldName, fieldValue) => {
form.emit('data', { name: 'field', key: fieldName, value: fieldValue });
});
form.once('end', () => {
console.log('Done!');
});
// If you want to customize whatever you want...
form.on('data', ({ name, key, value, buffer, start, end, formname, ...more }) => {
if (name === 'partBegin') {
}
if (name === 'partData') {
}
if (name === 'headerField') {
}
if (name === 'headerValue') {
}
if (name === 'headerEnd') {
}
if (name === 'headersEnd') {
}
if (name === 'field') {
console.log('field name:', key);
console.log('field value:', value);
}
if (name === 'file') {
console.log('file:', formname, value);
}
if (name === 'fileBegin') {
console.log('fileBegin:', formname, value);
}
});
A method that allows you to extend the Formidable library. By default we include
4 plugins, which esentially are adapters to plug the different built-in parsers.
The plugins added by this method are always enabled.
See src/plugins/ for more detailed look on default plugins.
The plugin param has such signature:
function(formidable: Formidable, options: Options): void;
The architecture is simple. The plugin is a function that is passed with the
Formidable instance (the form across the README examples) and the options.
Note: the plugin function's this context is also the same instance.
const formidable = require('formidable');
const form = formidable({ keepExtensions: true });
form.use((self, options) => {
// self === this === form
console.log('woohoo, custom plugin');
// do your stuff; check `src/plugins` for inspiration
});
form.parse(req, (error, fields, files) => {
console.log('done!');
});
Important to note, is that inside plugin this.options, self.options andoptions MAY or MAY NOT be the same. General best practice is to always use thethis, so you can later test your plugin independently and more easily.
If you want to disable some parsing capabilities of Formidable, you can disable
the plugin which corresponds to the parser. For example, if you want to disable
multipart parsing (so the src/parsers/Multipart.js
which is used in src/plugins/multipart.js), then
you can remove it from the options.enabledPlugins, like so
const { Formidable } = require('formidable');
const form = new Formidable({
hashAlgorithm: 'sha1',
enabledPlugins: ['octetstream', 'querystring', 'json'],
});
Be aware that the order MAY be important too. The names corresponds 1:1 to
files in src/plugins/ folder.
Pull requests for new built-in plugins MAY be accepted - for example, more
advanced querystring parser. Add your plugin as a new file in src/plugins/
folder (lowercased) and follow how the other plugins are made.
If you want to use Formidable to only handle certain parts for you, you can do
something similar. Or see
#387 for
inspiration, you can for example validate the mime-type.
const form = formidable();
form.onPart = (part) => {
part.on('data', (buffer) => {
// do whatever you want here
});
};
For example, force Formidable to be used only on non-file "parts" (i.e., html
fields)
const form = formidable();
form.onPart = function (part) {
// let formidable handle only non-file parts
if (part.originalFilename === '' || !part.mimetype) {
// used internally, please do not override!
form._handlePart(part);
}
};
export interface File {
// The size of the uploaded file in bytes.
// If the file is still being uploaded (see `'fileBegin'` event),
// this property says how many bytes of the file have been written to disk yet.
file.size: number;
// The path this file is being written to. You can modify this in the `'fileBegin'` event in
// case you are unhappy with the way formidable generates a temporary path for your files.
file.filepath: string;
// The name this file had according to the uploading client.
file.originalFilename: string | null;
// calculated based on options provided
file.newFilename: string | null;
// The mime type of this file, according to the uploading client.
file.mimetype: string | null;
// A Date object (or `null`) containing the time this file was last written to.
// Mostly here for compatibility with the [W3C File API Draft](http://dev.w3.org/2006/webapi/FileAPI/).
file.mtime: Date | null;
file.hashAlgorithm: false | |'sha1' | 'md5' | 'sha256'
// If `options.hashAlgorithm` calculation was set, you can read the hex digest out of this var (at the end it will be a string)
file.hash: string | object | null;
}
This method returns a JSON-representation of the file, allowing you toJSON.stringify() the file which is useful for logging and responding to
requests.
'progress'Emitted after each incoming chunk of data that has been parsed. Can be used to
roll your own progress bar.
form.on('progress', (bytesReceived, bytesExpected) => {});
'field'Emitted whenever a field / value pair has been received.
form.on('field', (name, value) => {});
'fileBegin'Emitted whenever a new file is detected in the upload stream. Use this event if
you want to stream the file to somewhere else while buffering the upload on the
file system.
form.on('fileBegin', (formName, file) => {
// accessible here
// formName the name in the form (<input name="thisname" type="file">) or http filename for octetstream
// file.originalFilename http filename or null if there was a parsing error
// file.newFilename generated hexoid or what options.filename returned
// file.filepath default pathnme as per options.uploadDir and options.filename
// file.filepath = CUSTOM_PATH // to change the final path
});
'file'Emitted whenever a field / file pair has been received. file is an instance ofFile.
form.on('file', (formname, file) => {
// same as fileBegin, except
// it is too late to change file.filepath
// file.hash is available if options.hash was used
});
'error'Emitted when there is an error processing the incoming form. A request that
experiences an error is automatically paused, you will have to manually callrequest.resume() if you want the request to continue firing 'data' events.
May have error.httpCode and error.code attached.
form.on('error', (err) => {});
'aborted'Emitted when the request was aborted by the user. Right now this can be due to a
'timeout' or 'close' event on the socket. After this event is emitted, anerror event will follow. In the future there will be a separate 'timeout'
event (needs a change in the node core).
form.on('aborted', () => {});
'end'Emitted when the entire request has been received, and all contained files have
finished flushing to disk. This is a great place for you to send your response.
form.on('end', () => {});
multipart_parser.js.If the documentation is unclear or has a typo, please click on the page's Edit
button (pencil icon) and suggest a correction. If you would like to help us fix
a bug or add a new feature, please check our Contributing
Guide. Pull requests are welcome!
Thanks goes to these wonderful people
(emoji key):
From a Felix blog post:
Formidable is licensed under the MIT License.
[nodejs-img]: https://badgen.net/badge/node/=%2010.13/green?cache=300
