@fastify/express

fastify-express

This plugin adds full Express compatibility to Fastify, it exposes the same use function of Express, and it allows you to use any Express middleware or application.

Note	This plugin should not be used as a long-term solution, it aims to help you have a smooth transition from Express to Fastify, but you should migrate your Express specific code to Fastify over time.

Install

npm i fastify-express

Usage

Register the plugin and start using your Express middlewares.

const Fastify = require('fastify')

async function build () {
  const fastify = Fastify()
  await fastify.register(require('fastify-express'))
  // do you know we also have cors support?
  // https://github.com/fastify/fastify-cors
  fastify.use(require('cors')())
  // express.Application is also accessible
  fastify.express.disabled('x-powered-by') // true
  return fastify
}

build()
  .then(fastify => fastify.listen(3000))
  .catch(console.log)

Add a complete application

You can register an entire Express application and make it work with Fastify. Remember, fastify-express is just express under the covers and requires the same body parsers as you'd use in express.

// index.js
const fastify = require('fastify')()
const express = require('express')
const router = express.Router()

router.use(function (req, res, next) {
  res.setHeader('x-custom', true)
  next()
})

router.get('/hello', (req, res) => {
  res.status(201)
  res.json({ hello: 'world' })
})

router.get('/foo', (req, res) => {
  res.status(400)
  res.json({ foo: 'bar' })
})

router.patch('/bar', (req, res) => {
  if (!req.body || Object.keys(req.body).length === 0) {
    res.status(400)
    res.json({ msg: 'no req.body'})
  } else {
    res.status(200)
    res.json(req.body)
  }
})

router.use('*', (req, res) => {
  res.status(404)
  res.json({ msg: 'not found'})
})

fastify.register(require('fastify-express'))
  .after(() => {
    fastify.use(express.urlencoded({extended: false})) // for Postman x-www-form-urlencoded
    fastify.use(express.json())

    fastify.use(router)
  })

fastify.listen(3000, console.log)

Testing Your App

Run node index.js to start your server. Then run the following commands to ensure your server is working. Use the optional -v flag in curl for verbose output.

me@computer ~ % curl -X GET http://localhost:3000/hello
{"hello":"world"}%
me@computer ~ % curl -X GET http://localhost:3000/foo
{"foo":"bar"}%
me@computer ~ % curl -X GET http://localhost:3000/bar
{"msg":"not found"}%
me@computer ~ % curl -X PATCH -H 'content-type:application/json' http://localhost:3000/bar  
{"msg":"no req.body"}%
me@computer ~ % curl -X PATCH -H 'content-type:application/json' -d '{"foo2":"bar2"}' http://localhost:3000/bar
{"foo2":"bar2"}%  

Encapsulation support

The encapsulation works as usual with Fastify, you can register the plugin in a subsystem and your express code will work only inside there, or you can declare the express plugin top level and register a middleware in a nested plugin, and the middleware will be executed only for the nested routes of the specific plugin.

Register the plugin in its own subsystem:

const fastify = require('fastify')()

fastify.register(subsystem)

async function subsystem (fastify, opts) {
  await fastify.register(require('fastify-express'))
  fastify.use(require('cors')())
}

Register a middleware in a specific plugin:

const fastify = require('fastify')()

fastify
  .register(require('fastify-express'))
  .register(subsystem)

async function subsystem (fastify, opts) {
  fastify.use(require('cors')())
}

Hooks and middlewares

Every registered middleware will be run during the onRequest hook phase, so the registration order is important.
Take a look at the Lifecycle documentation page to understand better how every request is executed.

const fastify = require('fastify')()

fastify
  .register(require('fastify-express'))
  .register(subsystem)

async function subsystem (fastify, opts) {
  fastify.addHook('onRequest', async (req, reply) => {
    console.log('first')
  })

  fastify.use((req, res, next) => {
    console.log('second')
    next()
  })

  fastify.addHook('onRequest', async (req, reply) => {
    console.log('third')
  })
}

Restrict middleware execution to a certain path(s)

If you need to run a middleware only under certain path(s), just pass the path as first parameter to use and you are done!

const fastify = require('fastify')()
const path = require('path')
const serveStatic = require('serve-static')

fastify
  .register(require('fastify-express'))
  .register(subsystem)

async function subsystem (fastify, opts) {
  // Single path
  fastify.use('/css', serveStatic(path.join(__dirname, '/assets')))

  // Wildcard path
  fastify.use('/css/*', serveStatic(path.join(__dirname, '/assets')))

  // Multiple paths
  fastify.use(['/css', '/js'], serveStatic(path.join(__dirname, '/assets')))
}

TypeScript support

To use this module with TypeScript, make sure to install @types/express.

You will need to add "types": ["fastify-express"] to your tsconfig.json file when using require to import the plugin.

Middlewares alternatives

Fastify offers some alternatives to the most commonly used middlewares, following, you can find a list.

Express Middleware	Fastify Plugin
helmet	fastify-helmet
cors	fastify-cors
serve-static	fastify-static

License

Licensed under MIT.
express license