@fastify/express/index.js

Express compatibility layer for Fastify

'use strict'

const fp = require('fastify-plugin')
const Express = require('express')
const kMiddlewares = Symbol('fastify-express-middlewares')

function fastifyExpress (fastify, options, next) {
  const {
    expressHook = 'onRequest',
    createProxyHandler
  } = options

  fastify.decorate('use', use)
  fastify[kMiddlewares] = []
  fastify.decorate('express', Express())
  fastify.express.disable('x-powered-by')

  fastify
    .addHook(expressHook, enhanceRequest)
    .addHook(expressHook, runConnect)
    .addHook('onRegister', onRegister)

  function use (path, fn) {
    if (typeof path === 'string') {
      const prefix = this.prefix
      path = prefix + (path === '/' && prefix.length > 0 ? '' : path)
    }
    this[kMiddlewares].push([path, fn])
    if (fn == null) {
      this.express.use(path)
    } else {
      this.express.use(path, fn)
    }
    return this
  }

  function enhanceRequest (req, reply, next) {
    // Allow attaching custom Proxy handlers to Express req
    if (typeof createProxyHandler === 'function') {
      req.raw = new Proxy(req.raw, createProxyHandler(req))
    }

    const { url } = req.raw
    req.raw.originalUrl = url
    req.raw.id = req.id
    req.raw.hostname = req.hostname
    req.raw.ip = req.ip
    req.raw.ips = req.ips
    req.raw.log = req.log
    reply.raw.log = req.log
    reply.raw.send = function send (...args) {
      // Restore req.raw.url to its original value https://github.com/fastify/fastify-express/issues/11
      req.raw.url = url
      return reply.send.apply(reply, args)
    }

    // backward compatibility for body-parser
    if (req.body) {
      req.raw.body = req.body
    }
    // backward compatibility for cookie-parser
    if (req.cookies) {
      req.raw.cookies = req.cookies
    }

    // Make it lazy as it does a bit of work
    Object.defineProperty(req.raw, 'protocol', {
      get () {
        return req.protocol
      }
    })

    next()
  }

  function runConnect (req, reply, next) {
    if (this[kMiddlewares].length > 0) {
      for (const [headerName, headerValue] of Object.entries(reply.getHeaders())) {
        reply.raw.setHeader(headerName, headerValue)
      }

      this.express(req.raw, reply.raw, next)
    } else {
      next()
    }
  }

  function onRegister (instance) {
    const middlewares = instance[kMiddlewares].slice()
    instance[kMiddlewares] = []
    instance.decorate('express', Express())
    instance.express.disable('x-powered-by')
    instance.decorate('use', use)
    for (const middleware of middlewares) {
      instance.use(...middleware)
    }
  }

  next()
}

module.exports = fp(fastifyExpress, {
  fastify: '5.x',
  name: '@fastify/express'
})
module.exports.default = fastifyExpress
module.exports.fastifyExpress = fastifyExpress