next-multiparty is a small utility library to ease the process of file uploads with Next.js. It uses formidable under the hood, but with much less work to do and a modern API

Installation is pretty straight forward. Simply run one of the following commands to install it to your Next.js app.

yarn add next-multiparty

npm i next-multiparty

pnpm add next-multiparty

TL;DR:

1. import { withFileUpload, getConfig } from 'next-multiparty'
2. Simply wrap any api route with withFileUpload
3. export const config = getConfig()
4. You now can access req.file (if the request contained one file field) or req.files
5. Call await req.file.toBuffer() to load the file into the memory

The withFileUpload function is a higher-order function which should be wrapped around an api route from next.js:

import { withFileUpload } from 'next-multiparty';
export default withFileUpload(async (req, res) => {
    res.json({test: 1})
})

By default it will attach the files and files which were posted to that endpoint to the NextApiRequest (in this case req) if the method was POST, PATCH or PUT and the Content-Type header was set to multipart/form-data.

If the request includes files they will be saved to the disk in the os.tmpdir() directory. After the execution of the handler all files will be cleaned up automatically.

The following properties are added to the Request:

• files: Array of EnhancedFile
• file: Single EnhancedFile. Will be undefined if there are no files
• fields: Object containing the name of the field as the key and the value of the field as the value

You can also pass a second parameter options to withFileUpload. Options is an object with the following values:

// Methods which should be allowed. Defaults to ['POST', 'PATCH', 'PUT']
allowedMethods?: HTTP_METHOD[];

// Flag whether the files should be removed after the execution of the handler. Defaults to true. You will probably not need to touch this.
cleanupFiles?: boolean;

// Options to change the behavior of formidable (e.g. max file size). Please refer to the https://github.com/node-formidable/formidable#options
formidableOptions?: formidable.Options

Basically just formidable.File but with two added helper functions:

// Loads the file asynchronously from the file system and loads it into the memory
// will throw if the file doesn't exists anymore
toBuffer: () => Promise<Buffer>

// Deletes the file from the file system if it exists
destroy: () => Promise<void>