next/server

next/server provides server-only helpers for use in Middleware and Edge API Routes.

NextRequest

The NextRequest object is an extension of the native Request interface, with the following added methods and properties:

  • cookies - A Map with cookies from the Request. See Using cookies in Edge Middleware
  • nextUrl: Includes an extended, parsed, URL object that gives you access to Next.js specific properties such as pathname, basePath, trailingSlash and i18n. Includes the following properties:
    • basePath (string)
    • buildId (string || undefined)
    • defaultLocale (string || undefined)
    • domainLocale
      • defaultLocale: (string)
      • domain: (string)
      • http: (boolean || undefined)
      • locales: (string[] || undefined)
    • locale (string || undefined)
    • url (URL)
  • ip: (string || undefined) - Has the IP address of the Request. This information is provided by your hosting platform.
  • geo - Has the geographic location from the Request. This information is provided by your hosting platform. Includes the following properties:
    • city (string || undefined)
    • country (string || undefined)
    • region (string || undefined)
    • latitude (string || undefined)
    • longitude (string || undefined)

You can use the NextRequest object as a direct replacement for the native Request interface, giving you more control over how you manipulate the request.

NextRequest can be imported from next/server:

import type { NextRequest } from 'next/server'

NextFetchEvent

The NextFetchEvent object extends the native FetchEvent object, and includes the waitUntil() method.

The waitUntil() method can be used to prolong the execution of the function if you have other background work to make.

import { NextResponse } from 'next/server'
import type { NextFetchEvent, NextRequest } from 'next/server'

export async function middleware(req: NextRequest, event: NextFetchEvent) {
  event.waitUntil(
    fetch('https://my-analytics-platform.com', {
      method: 'POST',
      body: JSON.stringify({ pathname: req.nextUrl.pathname }),
    })
  )

  return NextResponse.next()
}

The NextFetchEvent object can be imported from next/server:

import type { NextFetchEvent } from 'next/server'

NextResponse

The NextResponse class extends the native Response interface, with the following:

Public Methods

Public methods are available on an instance of the NextResponse class. Depending on your use case, you can create an instance and assign to a variable, then access the following public methods:

  • cookies - A Map with the cookies in the Response

Static Methods

The following static methods are available on the NextResponse class directly:

  • redirect() - Returns a NextResponse with a redirect set
  • rewrite() - Returns a NextResponse with a rewrite set
  • next() - Returns a NextResponse that will continue the middleware chain

To use the methods above, you must return the NextResponse object returned. NextResponse can be imported from next/server:

import { NextResponse } from 'next/server'

userAgent

The userAgent helper allows you to interact with the user agent object from the request. It is abstracted from the native Request object, and is an opt in feature. It has the following properties:

  • isBot: (boolean) Whether the request comes from a known bot
  • browser
    • name: (string || undefined) The name of the browser
    • version: (string || undefined) The version of the browser, determined dynamically
  • device
    • model: (string || undefined) The model of the device, determined dynamically
    • type: (string || undefined) The type of the browser, can be one of the following values: console, mobile, tablet, smarttv, wearable, embedded, or undefined
    • vendor: (string || undefined) The vendor of the device, determined dynamically
  • engine
    • name: (string || undefined) The name of the browser engine, could be one of the following values: Amaya, Blink, EdgeHTML, Flow, Gecko, Goanna, iCab, KHTML, Links, Lynx, NetFront, NetSurf, Presto, Tasman, Trident, w3m, WebKit or undefined
    • version: (string || undefined) The version of the browser engine, determined dynamically, or undefined
  • os
    • name: (string || undefined) The name of the OS, could be undefined
    • version: (string || undefined) The version of the OS, determined dynamically, or undefined
  • cpu
    • architecture: (string || undefined) The architecture of the CPU, could be one of the following values: 68k, amd64, arm, arm64, armhf, avr, ia32, ia64, irix, irix64, mips, mips64, pa-risc, ppc, sparc, sparc64 or undefined

userAgent can be imported from next/server:

import { userAgent } from 'next/server'
import { NextRequest, NextResponse, userAgent } from 'next/server'

export function middleware(request: NextRequest) {
  const url = request.nextUrl
  const { device } = userAgent(request)
  const viewport = device.type === 'mobile' ? 'mobile' : 'desktop'
  url.searchParams.set('viewport', viewport)
  return NextResponse.rewrite(url)
}

FAQ

Why does redirect use 307 and 308?

When using redirect() you may notice that the status codes used are 307 for a temporary redirect, and 308 for a permanent redirect. While traditionally a 302 was used for a temporary redirect, and a 301 for a permanent redirect, many browsers changed the request method of the redirect, from a POST to GET request when using a 302, regardless of the origins request method.

Taking the following example of a redirect from /users to /people, if you make a POST request to /users to create a new user, and are conforming to a 302 temporary redirect, the request method will be changed from a POST to a GET request. This doesn't make sense, as to create a new user, you should be making a POST request to /people, and not a GET request.

The introduction of the 307 status code means that the request method is preserved as POST.

  • 302 - Temporary redirect, will change the request method from POST to GET
  • 307 - Temporary redirect, will preserve the request method as POST

The redirect() method uses a 307 by default, instead of a 302 temporary redirect, meaning your requests will always be preserved as POST requests.

If you want to cause a GET response to a POST request, use 303.

Learn more about HTTP Redirects.

How do I access Environment Variables?

process.env can be used to access Environment Variables from Edge Middleware. They are evaluated during next build:

WorksDoes not work
console.log(process.env.MY_ENV_VARIABLE)const getEnv = name => process.env[name]
const { MY_ENV_VARIABLE } = process.env
const { "MY-ENV-VARIABLE": MY_ENV_VARIABLE } = process.env

Related