middleware-multipart.md

description
A multipart/form-data middleware based on busboy library.

@marblejs/middleware-multipart

Installation

yarn add @marblejs/middleware-multipart

Requires @marblejs/core to be installed.

Importing

import { multipart$ } from '@marblejs/middleware-multipart';

Type declaration

multipart$ :: ParserOpts -> HttpMiddlewareEffect

Parameters

parameter	definition
options	<optional> ParserOpts

ParserOpts

parameter	definition
files	<optional> Array<string>
stream	<optional> StreamHandler
maxFileSize	<optional> number
maxFileCount	<optional> number
maxFieldSize	<optional> number
maxFieldCount	<optional> number

Usage

{% hint style="warning" %} Make sure that you always handle the files that a user uploads. Never add it as a global middleware since a malicious user could upload files to a route that you didn't handle. Only use this it on routes where you are handling the uploaded files. {% endhint %}

In-memory storage:

import { multipart$ } from '@marblejs/middleware-multipart';

const effect$ = r.pipe(
  r.matchPath('/'),
  r.matchType('POST'),
  r.useEffect(req$ => req$.pipe(
    use(multipart$()),
    map(req => ({ body: {
      files: req.files,    // file data
      body: req.body,      // all incoming body fields
    }}))
  )));

Out-of-memory storage:

import { multipart$, StreamHandler } from '@marblejs/middleware-multipart';

const stream: StreamHandler = ({ file, fieldname }) => {
  // stream here incoming file to different location...
  const destination = // ... and grab the persisted file location
  return of({ destination });
};

const effect$ = r.pipe(
  r.matchPath('/'),
  r.matchType('POST'),
  r.useEffect(req$ => req$.pipe(
    use(multipart$({
      stream,
      maxFileCount: 1,
      files: ['image_1'],
    })),
    map(req => ({ body: {
      files: req.files['image_1'],  // file data
      body: req.body,               // all incoming body fields
    }}))
  )));

You can intercept incoming files and stream them to the different place, eg. to OS filesystem or AWS S3 bucket. The prervious example shows how you can specify constraints for multipart/form-data parsing the accepts only one image_1 field.

Each file included inside req.files object contains the following information:

key	description
fieldname	Field name specified in the form
filename	Name of the file on the user's computer
encoding	Encoding type of the file
mimetype	Mime type of the file
size	Size of the file in bytes (in-memory parsing)
destination	The place in which the file has been saved (if not in-memory parsing)
buffer	A Buffer of the entire file (in-memory parsing)

You can define the following middleware options:

key	description
maxFileCount	The total count of files that can be sent
maxFieldCount	The total count of fields that can be sent
maxFileSize	The max possible file size in bytes
files	An array of acceptable field names
stream	A handler which you can use to stream incoming files to different location