# busboy
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Description =========== A Node.js module for parsing incoming HTML form data. This is an officially supported fork by [fastify](https://github.com/fastify/) organization of the amazing library [originally created](https://github.com/mscdex/busboy) by Brian White, aimed at addressing long-standing issues with it. Benchmark (Mean time for 500 Kb payload, 2000 cycles, 1000 cycle warmup): | Library | Version | Mean time in nanoseconds (less is better) | |-----------------------|---------|-------------------------------------------| | busboy | 0.3.1 | `340114` | | @fastify/busboy | 1.0.0 | `270984` | [Changelog](https://github.com/fastify/busboy/blob/master/CHANGELOG.md) since busboy 0.31. Requirements ============ * [Node.js](http://nodejs.org/) 10+ Install ======= npm i @fastify/busboy Examples ======== * Parsing (multipart) with default options: ```javascript const http = require('node:http'); const { inspect } = require('node:util'); const Busboy = require('busboy'); http.createServer((req, res) => { if (req.method === 'POST') { const busboy = new Busboy({ headers: req.headers }); busboy.on('file', (fieldname, file, filename, encoding, mimetype) => { console.log(`File [${fieldname}]: filename: ${filename}, encoding: ${encoding}, mimetype: ${mimetype}`); file.on('data', data => { console.log(`File [${fieldname}] got ${data.length} bytes`); }); file.on('end', () => { console.log(`File [${fieldname}] Finished`); }); }); busboy.on('field', (fieldname, val, fieldnameTruncated, valTruncated, encoding, mimetype) => { console.log(`Field [${fieldname}]: value: ${inspect(val)}`); }); busboy.on('finish', () => { console.log('Done parsing form!'); res.writeHead(303, { Connection: 'close', Location: '/' }); res.end(); }); req.pipe(busboy); } else if (req.method === 'GET') { res.writeHead(200, { Connection: 'close' }); res.end(`


`); } }).listen(8000, () => { console.log('Listening for requests'); }); // Example output, using http://nodejs.org/images/ryan-speaker.jpg as the file: // // Listening for requests // File [filefield]: filename: ryan-speaker.jpg, encoding: binary // File [filefield] got 11971 bytes // Field [textfield]: value: 'testing! :-)' // File [filefield] Finished // Done parsing form! ``` * Save all incoming files to disk: ```javascript const http = require('node:http'); const path = require('node:path'); const os = require('node:os'); const fs = require('node:fs'); const Busboy = require('busboy'); http.createServer(function(req, res) { if (req.method === 'POST') { const busboy = new Busboy({ headers: req.headers }); busboy.on('file', function(fieldname, file, filename, encoding, mimetype) { var saveTo = path.join(os.tmpdir(), path.basename(fieldname)); file.pipe(fs.createWriteStream(saveTo)); }); busboy.on('finish', function() { res.writeHead(200, { 'Connection': 'close' }); res.end("That's all folks!"); }); return req.pipe(busboy); } res.writeHead(404); res.end(); }).listen(8000, function() { console.log('Listening for requests'); }); ``` * Parsing (urlencoded) with default options: ```javascript const http = require('node:http'); const { inspect } = require('node:util'); const Busboy = require('busboy'); http.createServer(function(req, res) { if (req.method === 'POST') { const busboy = new Busboy({ headers: req.headers }); busboy.on('file', function(fieldname, file, filename, encoding, mimetype) { console.log('File [' + fieldname + ']: filename: ' + filename); file.on('data', function(data) { console.log('File [' + fieldname + '] got ' + data.length + ' bytes'); }); file.on('end', function() { console.log('File [' + fieldname + '] Finished'); }); }); busboy.on('field', function(fieldname, val, fieldnameTruncated, valTruncated) { console.log('Field [' + fieldname + ']: value: ' + inspect(val)); }); busboy.on('finish', function() { console.log('Done parsing form!'); res.writeHead(303, { Connection: 'close', Location: '/' }); res.end(); }); req.pipe(busboy); } else if (req.method === 'GET') { res.writeHead(200, { Connection: 'close' }); res.end('\
\
\
\ Node.js rules!
\ \
\ '); } }).listen(8000, function() { console.log('Listening for requests'); }); // Example output: // // Listening for requests // Field [textfield]: value: 'testing! :-)' // Field [selectfield]: value: '9001' // Field [checkfield]: value: 'on' // Done parsing form! ``` API === _Busboy_ is a _Writable_ stream Busboy (special) events ----------------------- * **file**(< _string_ >fieldname, < _ReadableStream_ >stream, < _string_ >filename, < _string_ >transferEncoding, < _string_ >mimeType) - Emitted for each new file form field found. `transferEncoding` contains the 'Content-Transfer-Encoding' value for the file stream. `mimeType` contains the 'Content-Type' value for the file stream. * Note: if you listen for this event, you should always handle the `stream` no matter if you care about the file contents or not (e.g. you can simply just do `stream.resume();` if you want to discard the contents), otherwise the 'finish' event will never fire on the Busboy instance. However, if you don't care about **any** incoming files, you can simply not listen for the 'file' event at all and any/all files will be automatically and safely discarded (these discarded files do still count towards `files` and `parts` limits). * If a configured file size limit was reached, `stream` will both have a boolean property `truncated` (best checked at the end of the stream) and emit a 'limit' event to notify you when this happens. * The property `bytesRead` informs about the number of bytes that have been read so far. * **field**(< _string_ >fieldname, < _string_ >value, < _boolean_ >fieldnameTruncated, < _boolean_ >valueTruncated, < _string_ >transferEncoding, < _string_ >mimeType) - Emitted for each new non-file field found. * **partsLimit**() - Emitted when specified `parts` limit has been reached. No more 'file' or 'field' events will be emitted. * **filesLimit**() - Emitted when specified `files` limit has been reached. No more 'file' events will be emitted. * **fieldsLimit**() - Emitted when specified `fields` limit has been reached. No more 'field' events will be emitted. Busboy methods -------------- * **(constructor)**(< _object_ >config) - Creates and returns a new Busboy instance. * The constructor takes the following valid `config` settings: * **headers** - _object_ - These are the HTTP headers of the incoming request, which are used by individual parsers. * **autoDestroy** - _boolean_ - Whether this stream should automatically call .destroy() on itself after ending. (Default: false). * **highWaterMark** - _integer_ - highWaterMark to use for this Busboy instance (Default: WritableStream default). * **fileHwm** - _integer_ - highWaterMark to use for file streams (Default: ReadableStream default). * **defCharset** - _string_ - Default character set to use when one isn't defined (Default: 'utf8'). * **preservePath** - _boolean_ - If paths in the multipart 'filename' field shall be preserved. (Default: false). * **isPartAFile** - __function__ - Use this function to override the default file detection functionality. It has following parameters: * fieldName - __string__ The name of the field. * contentType - __string__ The content-type of the part, e.g. `text/plain`, `image/jpeg`, `application/octet-stream` * fileName - __string__ The name of a file supplied by the part. (Default: `(fieldName, contentType, fileName) => (contentType === 'application/octet-stream' || fileName !== undefined)`) * **limits** - _object_ - Various limits on incoming data. Valid properties are: * **fieldNameSize** - _integer_ - Max field name size (in bytes) (Default: 100 bytes). * **fieldSize** - _integer_ - Max field value size (in bytes) (Default: 1 MiB, which is 1024 x 1024 bytes). * **fields** - _integer_ - Max number of non-file fields (Default: Infinity). * **fileSize** - _integer_ - For multipart forms, the max file size (in bytes) (Default: Infinity). * **files** - _integer_ - For multipart forms, the max number of file fields (Default: Infinity). * **parts** - _integer_ - For multipart forms, the max number of parts (fields + files) (Default: Infinity). * **headerPairs** - _integer_ - For multipart forms, the max number of header key=>value pairs to parse **Default:** 2000 * **headerSize** - _integer_ - For multipart forms, the max size of a multipart header **Default:** 81920. * The constructor can throw errors: * **Busboy expected an options-Object.** - Busboy expected an Object as first parameters. * **Busboy expected an options-Object with headers-attribute.** - The first parameter is lacking of a headers-attribute. * **Limit $limit is not a valid number** - Busboy expected the desired limit to be of type number. Busboy throws this Error to prevent a potential security issue by falling silently back to the Busboy-defaults. Potential source for this Error can be the direct use of environment variables without transforming them to the type number. * **Unsupported Content-Type.** - The `Content-Type` isn't one Busboy can parse. * **Missing Content-Type-header.** - The provided headers don't include `Content-Type` at all.