@goa/busboy NPM

@goa/busboy

@goa/busboy is a fork of A Streaming Parser For HTML Form Data For Node.JS Written In ES6 And Optimised With JavaScript Compiler.

yarn add @goa/busboy

API

The package is available by importing its default function:

import Busboy from '@goa/busboy'

`class Busboy`

Busboy is a Writable stream. Emits the following events:

Event	Description
file	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.
field	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.

File Event

busboy.on('file',
  <string> fieldname,
  <ReadableStream> stream,
  <string> filename,
  <string> transferEncoding,
  <string> mimeType
)

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.

Field Event

busboy.on('field',
  <string> fieldname,
  <string> value,
  <boolean> fieldnameTruncated,
  <boolean> valueTruncated,
  <string> transferEncoding,
  <string> mimeType
)

constructor( `conf=: !BusBoyConfig,`): BusBoy

conf !BusBoyConfig (optional): The configuration.

BusBoyConfig: Options for the program.

Name	Type	Description	Default
headers	!Object	These are the HTTP headers of the incoming request, which are used by individual parsers.	-
highWaterMark	number	The `highWaterMark` to use for this Busboy instance (Default: WritableStream default).	-
fileHwm	number	The `highWaterMark` to use for file streams (Default: ReadableStream default).	-
defCharset	string	The default character set to use when one isn't defined.	`utf8`
preservePath	boolean	If paths in the multipart 'filename' field shall be preserved.	`false`
limits	BusBoyLimits	Various limits on incoming data.	-

BusBoyLimits: Various limits on incoming data.

Name	Type	Description	Default
fieldNameSize	number	Max field name size in bytes.	`100`
fieldSize	number	Max field value size in bytes.	`1024`
fields	number	Max number of non-file fields.	`Infinity`
fileSize	number	For multipart forms, the max file size in bytes.	`Infinity`
files	number	For multipart forms, the max number of file fields.	`Infinity`
parts	number	For multipart forms, the max number of parts (fields + files).	`Infinity`
headerPairs	number	For multipart forms, the max number of header key=> value pairs to parse.	`2000`

The constructor can throw errors:

Unsupported content type: $type - The Content-Type isn't one Busboy can parse.
Missing Content-Type - The provided headers don't include Content-Type at all.

import idio from '@idio/idio'
import render from '@depack/render'
import Busboy from '@goa/busboy'

(async () => {
  const { app, url } = await idio({
    async post(ctx, next) {
      if (ctx.request.method != 'POST') {
        return await next()
      }
      const busboy = new Busboy({ headers: ctx.request.headers })

      busboy.on('file', function(fieldname, file, filename, encoding, mimetype) {
        console.log(
          'File [%s]: filename: %s, encoding: %s, mimetype: %s',
          fieldname, filename, encoding, mimetype)
        file.on('data', (data) => {
          console.log('File [%s] got %s bytes', fieldname, data.length)
        })
        file.on('end', () => {
          console.log('File [%s] Finished', fieldname)
        })
      })

      busboy.on('field', (
        fieldname, val, fieldnameTruncated, valTruncated, encoding, mimetype,
      ) => {
        console.log('Field [%s]: value: %O', fieldname, val)
      })

      ctx.req.pipe(busboy)

      await new Promise((r, j) => {
        busboy.on('finish', () => {
          console.log('Done parsing form!')
          r()
        }).on('error', j)
      })
      ctx.status = 303
      ctx.body = 'OK'
      exitExample(app)
    },
    get(ctx) {
      ctx.body = render(<html>
        <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>)
    },
  })
  console.log(url)
})()

http://localhost:5000
Field [textfield]: value: ''
File [filefield]: filename: hi, encoding: 7bit, mimetype: application/octet-stream
File [filefield] got 12 bytes
File [filefield] Finished
Done parsing form!