Fastify plugin to parse the multipart content-type. Supports:
- Async / Await
- Async iterator support to handle multiple parts
- Stream & Disk mode
- Accumulate whole file in memory
- Mode to attach all fields to the request body
- Tested across Linux/Mac/Windows
Under the hood it uses busboy.
npm i fastify-multipart
If you are looking for the documentation for the legacy callback-api please see here.
const fastify = require('fastify')()
const fs = require('fs')
const util = require('util')
const path = require('path')
const { pipeline } = require('stream')
const pump = util.promisify(pipeline)
fastify.register(require('fastify-multipart'))
fastify.post('/', async function (req, reply) {
// process a single file
// also, consider that if you allow to upload multiple files
// you must consume all files otherwise the promise will never fulfill
const data = await req.file()
data.file // stream
data.fields // other parsed parts
data.fieldname
data.filename
data.encoding
data.mimetype
// to accumulate the file in memory! Be careful!
//
// await data.toBuffer() // Buffer
//
// or
await pump(data.file, fs.createWriteStream(data.filename))
// be careful of permission issues on disk and not overwrite
// sensitive files that could cause security risks
// also, consider that if the file stream is not consumed, the promise will never fulfill
reply.send()
})
fastify.listen(3000, err => {
if (err) throw err
console.log(`server listening on ${fastify.server.address().port}`)
})You can also pass optional arguments to busboy when registering with fastify. This is useful for setting limits on the content that can be uploaded. A full list of available options can be found in the busboy documentation.
Note: if the file stream that is provided by data.file is not consumed (like in the example above with the usage of pump) the promise won't be fulfilled at the end of the multipart processing.
This behavior is inherited from busboy.
fastify.register(require('fastify-multipart'), {
limits: {
fieldNameSize: 100, // Max field name size in bytes
fieldSize: 1000000, // Max field value size in bytes
fields: 10, // Max number of non-file fields
fileSize: 100, // For multipart forms, the max file size
files: 1, // Max number of file fields
headerPairs: 2000 // Max number of header key=>value pairs
}
});If you do set upload limits, be sure to catch the error. An error or exception will occur if a limit is reached. These events are documented in more detail here.
Note: if the file stream that is provided by data.file is not consumed (like in the example below with the usage of pump) the promise won't be fulfilled at the end of the multipart processing.
This behavior is inherited from busboy.
try {
const data = await req.file()
await pump(data.file, fs.createWriteStream(data.filename))
} catch (error) {
if (error instanceof fastify.multipartErrors.FilesLimitError) {
// handle error
}
}Additionally, you can pass per-request options to the req.file, req.files, req.saveRequestFiles or req.multipartIterator function.
fastify.post('/', async function (req, reply) {
const options = { limits: { fileSize: 1000 } };
const data = await req.file(options)
await pump(data.file, fs.createWriteStream(data.filename))
reply.send()
})fastify.post('/', async function (req, reply) {
const parts = await req.files()
for await (const part of parts) {
await pump(part.file, fs.createWriteStream(part.filename))
}
reply.send()
})fastify.post('/upload/raw/any', async function (req, reply) {
const parts = await req.parts()
for await (const part of parts) {
if (part.file) {
await pump(part.file, fs.createWriteStream(part.filename))
} else {
console.log(part)
}
}
reply.send()
})fastify.post('/upload/raw/any', async function (req, reply) {
const data = await req.file()
const buffer = await data.toBuffer()
// upload to S3
reply.send()
})This will store all files in the operating system default directory for temporary files. As soon as the response ends all files are removed.
fastify.post('/upload/files', async function (req, reply) {
// stores files to tmp dir and return files
const files = await req.saveRequestFiles()
files[0].filepath
files[0].fieldname
files[0].filename
files[0].encoding
files[0].mimetype
files[0].fields // other parsed parts
reply.send()
})This allows you to parse all fields automatically and assign them to the request.body. By default files are accumulated in memory (Be careful!) to buffer objects. Uncaught errors are handled by fastify.
fastify.register(require('fastify-multipart'), { attachFieldsToBody: true })
fastify.post('/upload/files', async function (req, reply) {
const uploadValue = await req.body.upload.toBuffer() // access files
const fooValue = await req.body.foo.value // other fields
})You can also define a onFile handler to avoid accumulate all files in memory.
async function onFile(part) {
await pump(part.file, fs.createWriteStream(part.filename))
}
fastify.register(require('fastify-multipart'), { attachFieldsToBody: true, onFile })
fastify.post('/upload/files', async function (req, reply) {
const fooValue = await req.body.foo.value // other fields
})If you enable attachFieldsToBody and set sharedSchemaId a shared JSON Schema is added which can be used to validate parsed multipart fields.
const opts = {
attachFieldsToBody: true,
sharedSchemaId: '#mySharedSchema'
}
fastify.register(require('fastify-multipart'), opts)
fastify.post('/upload/files', {
schema: {
body: {
type: 'object',
required: ['myField'],
properties: {
myField: { $ref: '#mySharedSchema'},
// or
myFiles: { type: 'array', items: fastify.getSchema('mySharedSchema') },
// or
hello: {
properties: {
value: {
type: 'string',
enum: ['male']
}
}
}
}
}
}
}, function (req, reply) {
console.log({ body: req.body })
reply.send('done')
})We export all custom errors via a server decorator fastify.multipartErrors. This is useful if you want to react to specific errors. They are derivated from fastify-error and include the correct statusCode property.
fastify.post('/upload/files', async function (req, reply) {
const { FilesLimitError } = fastify.multipartErrors
})This project is kindly sponsored by:
Licensed under MIT.