The busboy npm package is a Node.js module for parsing incoming HTML form data, particularly file uploads. It is a stream-based parser that can handle multipart/form-data, which is primarily used for uploading files via HTTP.
File Upload Parsing
This code sample demonstrates how to use busboy to parse file uploads from an HTML form. When a file is received, it logs the file details and the amount of data received.
const Busboy = require('busboy');
const http = require('http');
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 ${data.length} bytes`);
}).on('end', () => {
console.log(`File [${fieldname}] Finished`);
});
});
busboy.on('finish', () => {
console.log('Done parsing form!');
res.writeHead(303, { Connection: 'close', Location: '/' });
res.end();
});
req.pipe(busboy);
} else {
res.writeHead(404);
res.end();
}
}).listen(8000, () => {
console.log('Server listening on port 8000');
});Field Parsing
This code sample shows how to use busboy to parse non-file fields from an HTML form. It logs the name and value of each field received.
const Busboy = require('busboy');
const http = require('http');
http.createServer((req, res) => {
if (req.method === 'POST') {
const busboy = new Busboy({ headers: req.headers });
busboy.on('field', (fieldname, val, fieldnameTruncated, valTruncated, encoding, mimetype) => {
console.log(`Field [${fieldname}]: value: ${val}`);
});
busboy.on('finish', () => {
res.end('Done parsing form!');
});
req.pipe(busboy);
} else {
res.writeHead(404);
res.end();
}
}).listen(8000, () => {
console.log('Server listening on port 8000');
});Formidable is an npm package similar to busboy that is used for parsing form data, especially file uploads. It is also stream-based and can handle multipart/form-data. Compared to busboy, Formidable provides a higher-level abstraction and can also handle file uploads to disk, but it might be less efficient for large file uploads due to its buffering approach.
Multiparty is another npm package for parsing multipart/form-data. Like busboy, it is stream-based and suitable for handling large file uploads. However, multiparty differs in its API and the way it handles parts of the form data, which may make it more suitable for certain use cases.
Multer is a middleware for Express.js that handles multipart/form-data, which is primarily used for uploading files. It is built on top of busboy for maximum efficiency. Unlike busboy, which is a general-purpose stream parser, multer provides a set of convenient features specifically designed for Express applications.
A node.js module for parsing incoming HTML form data.
npm install busboy
var http = require('http'),
inspect = require('util').inspect;
var Busboy = require('busboy');
http.createServer(function(req, res) {
if (req.method === 'POST') {
var busboy = new Busboy({ headers: req.headers });
busboy.on('file', function(fieldname, file, filename, encoding, mimetype) {
console.log('File [' + fieldname + ']: filename: ' + filename + ', encoding: ' + encoding);
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, valTruncated, keyTruncated) {
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('<html><head></head><body>\
<form method="POST" enctype="multipart/form-data">\
<input type="text" name="textfield"><br />\
<input type="file" name="filefield"><br />\
<input type="submit">\
</form>\
</body></html>');
}
}).listen(8000, function() {
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!
var http = require('http'),
path = require('path'),
os = require('os');
var Busboy = require('busboy');
http.createServer(function(req, res) {
if (req.method === 'POST') {
var 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');
});
var http = require('http'),
inspect = require('util').inspect;
var Busboy = require('busboy');
http.createServer(function(req, res) {
if (req.method === 'POST') {
var 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, valTruncated, keyTruncated) {
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('<html><head></head><body>\
<form method="POST">\
<input type="text" name="textfield"><br />\
<select name="selectfield">\
<option value="1">1</option>\
<option value="10">10</option>\
<option value="100">100</option>\
<option value="9001">9001</option>\
</select><br />\
<input type="checkbox" name="checkfield">Node.js rules!<br />\
<input type="submit">\
</form>\
</body></html>');
}
}).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!
Busboy is a Writable stream
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.
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).stream also has a boolean property 'truncated', which indicates if the file stream was truncated because a configured file size limit was reached. It's probably best to check this value at the end of the stream.field(< string >fieldname, < string >value, < boolean >fieldnameTruncated, < boolean >valueTruncated) - 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.
(constructor)(< object >config) - Creates and returns a new Busboy instance with the following valid config settings:
headers - object - These are the HTTP headers of the incoming request, which are used by individual parsers.
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').
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: 1MB).
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 (same as node's http).
FAQs
A streaming parser for HTML form data for node.js
We found that busboy demonstrated a not healthy version release cadence and project activity because the last version was released a year ago. It has 1 open source maintainer collaborating on the project.
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