@multipart/form-data

@multipart/form-data is Multipart/Form-Data And File Upload Middleware For Koa Written In ES6 And Optimised With JavaScript Compiler.

Originally, this was a Multer fork, however it was rewritten specifically for Koa2, and the interfaces were updated to be async rather than callbacks. Differences:

When the file size limit is reached, the next middleware is called, rather than waiting to drain the request stream. This can result in the client-side EPIPE (connection reset) errors when sending files larger than allowed. But ideally, Node.JS applications should be run behind a proxy such as NginX to limit the upload size.
Removes the unnecessary typeis dependency that includes the mime-type database, just checks the Content-Type to start with multipart/form-data.
Compiled with Google Closure Compiler and has just 1 dependency (text-decoding) to decode non-utf8 fields (e.g., when a form submitted had the accept-charset attribute).

yarn add @multipart/form-data

Table Of Contents
API
class FormData
FormDataFile
Copyright & License

API

The package is available by importing its default and named functions:

import FormData, {
  diskStorage, memoryStorage, FormDataError,
} from '@multipart/form-data'

`class FormData`

This class is used to create middleware according to the required file upload strategy.

FormData: An instance to create middleware.

Name	Type & Description
constructor	new (options?: !FormDataConfig) => FormData

	Creates a new form-data instance.
single	(name: string) => !_goa.Middleware

	Accept a single file.
array	(name: string, maxFiles: string) => !_goa.Middleware

	Accept multiple files.
fields	(fields: !Array<FormDataField>) => !_goa.Middleware

	Accept files according to the configured fields.
none	() => !_goa.Middleware

	Do not accept files, only fields.
any	() => !_goa.Middleware

	Accept any fields and files.

Creates a new instance according to the config. It is later used to access the middleware functions described below.

FormDataConfig: The configuration for the instance.

Name	Type	Description	Default
dest	string	The directory where to store the files using the `DiskStorage`. If not specified, files will be saved in the system's temp directory (`os.tmpdir()`).	-
storage	FormDataStorageEngine	An instance of a custom storage engine.	-
fileFilter	FormDataFileFilter	The file filter.	-
limits	_goa.BusBoyLimits	The limits of the uploaded data.	-
preservePath	boolean	Whether to keep the full path of files instead of just the base name.	`false`

`single(fieldname)`: Accept a single file.

import Multipart from '@multipart/form-data'
import Goa from '@goa/koa'

const app = new Goa()
const multipart = new Multipart({
  dest: 'temp',
})
const middleware = multipart.single('file')
app.use(middleware)
app.use((ctx) => {
  console.log('Fields: %O', ctx.req.body)
  delete ctx.req.file.stream
  console.log('File: %O', ctx.req.file)
})

Fields: { hello: 'world', name: 'multipart' }
File: { fieldname: 'file',
  originalname: 'test.txt',
  encoding: '7bit',
  mimetype: 'application/octet-stream',
  destination: 'temp',
  filename: 'afb49cada5f721d7fa8337f072d03ec5',
  path: 'temp/afb49cada5f721d7fa8337f072d03ec5',
  size: 12 }

`array(fieldname, maxCount)`: Accept multiple files under the same field name.

import Multipart from '@multipart/form-data'
import Goa from '@goa/koa'

const app = new Goa()
const multipart = new Multipart({
  dest: 'temp',
  preservePath: true,
})
const middleware = multipart.array('file', 2)
app.use(middleware)
app.use((ctx) => {
  log('Fields', ctx.req.body)
  log('Files', ctx.req.files)
})

Fields: { hello: 'world', name: 'multipart' }
Files: [ { fieldname: 'file',
    originalname: 'test/fixture/test.txt',
    encoding: '7bit',
    mimetype: 'application/octet-stream',
    destination: 'temp',
    filename: '0fa202db40',
    path: 'temp/0fa202db40',
    size: 12 },
  { fieldname: 'file',
    originalname: 'test/fixture/test.txt',
    encoding: '7bit',
    mimetype: 'application/octet-stream',
    destination: 'temp',
    filename: '149e4b08d6',
    path: 'temp/149e4b08d6',
    size: 12 } ]

`fields(Array<FormDataField>)`: Accept files according to the configured fields and place them in a hashmap.

Click to show the FormDataField interface.

FormDataField: The item to use in the .fields method.

Name	Type	Description
name*	string	The name of the field.
maxCount	number	The maximum count of the field.

import Multipart from '@multipart/form-data'
import Goa from '@goa/koa'

const app = new Goa()
const multipart = new Multipart({
  dest: 'temp',
})
const middleware = multipart.fields([
  { name: 'file', maxCount: 2 },
  { name: 'picture', maxCount: 1 },
])
app.use(middleware)
app.use((ctx) => {
  log('Fields', ctx.req.body)
  log('Files', ctx.req.files)
})

Fields: { hello: 'world', name: 'multipart' }
Files: { file: 
   [ { fieldname: 'file',
       originalname: 'test.txt',
       encoding: '7bit',
       mimetype: 'application/octet-stream',
       destination: 'temp',
       filename: '13093f0764',
       path: 'temp/13093f0764',
       size: 12 },
     { fieldname: 'file',
       originalname: 'test.txt',
       encoding: '7bit',
       mimetype: 'application/octet-stream',
       destination: 'temp',
       filename: '22e2e6e6f7',
       path: 'temp/22e2e6e6f7',
       size: 12 } ],
  picture: 
   [ { fieldname: 'picture',
       originalname: 'large.jpg',
       encoding: '7bit',
       mimetype: 'application/octet-stream',
       destination: 'temp',
       filename: '352a1aea6a',
       path: 'temp/352a1aea6a',
       size: 1592548 } ] }

`none()`: Do not accept files, only fields.

import Multipart from '@multipart/form-data'
import Goa from '@goa/koa'

const app = new Goa()
const multipart = new Multipart({
  dest: 'temp',
})
const middleware = multipart.none()
app.use(middleware)
app.use((ctx) => {
  log('Fields', ctx.req.body)
  log('Files', ctx.req.files)
})

Fields: { hello: 'world', name: 'multipart' }
Files: undefined

`any()`: Accept all files and fields.

import Multipart from '@multipart/form-data'
import Goa from '@goa/koa'

const app = new Goa()
const multipart = new Multipart({
  dest: 'temp',
})
const middleware = multipart.any()
app.use(middleware)
app.use((ctx) => {
  log('Fields', ctx.req.body)
  log('Files', ctx.req.files)
})

Fields: { hello: 'world', name: 'multipart' }
Files: [ { fieldname: 'file',
    originalname: 'test.txt',
    encoding: '7bit',
    mimetype: 'application/octet-stream',
    destination: 'temp',
    filename: '7218bd891a',
    path: 'temp/7218bd891a',
    size: 12 },
  { fieldname: 'picture',
    originalname: 'large.jpg',
    encoding: '7bit',
    mimetype: 'application/octet-stream',
    destination: 'temp',
    filename: 'e7a8050980',
    path: 'temp/e7a8050980',
    size: 1592548 } ]

`FormDataFile`

MultipartFormData adds a body object and a file or files object to the request object. The body hashmap contains the values of the text fields of the form, the file or files object contains the files uploaded via the form.

import('stream').Readable stream.Readable: A stream that pushes data when it becomes available.

FormDataFile: The information about each file.

Name	Type	Description
fieldname*	string	The field name specified in the form.
originalname*	string	The name of the file on the user's computer.
encoding*	string	The encoding type of the file.
mimetype*	string	The mime type of the file.
size*	number	The size of the file in bytes.
destination*	string	The folder to which the file has been saved. Set by DiskStorage.
filename*	string	The name of the file within the `destination`. Set by DiskStorage.
path*	string	The full path to the uploaded file. Set by DiskStorage.
buffer*	Buffer	The `Buffer` of the entire file. Set by MemoryStorage.
stream*	stream.Readable	The Readable stream with the file data. This stream should not be read other than by a storage engine.

Copyright & License

GNU Affero General Public License v3.0

Original work by Multer's contributors under MIT license found in COPYING.

	© Art Deco for Idio 2019			Tech Nation Visa Sucks