Introduction

Goal of the Tutorial

The purpose of this tutorial is to introduce you to the basics of authentication in Next.js. By the end of this tutorial, you should have a good understanding of what authentication is, why it's important, and how it's integrated into Next.js applications.

Learning Outcomes

• Understanding of what authentication is.
• The importance of authentication in web development.
• Integration of authentication in Next.js applications.
• Working with an example of authentication in Next.js.

Prerequisites

• Basic knowledge of JavaScript.
• Familiarity with React.js and Next.js.
• Basic understanding of web development concepts.

Step-by-Step Guide

Authentication is the process of verifying the identity of a user. It's an essential part of most web applications.

In Next.js, one common way to add authentication is by using the NextAuth.js library. This is an easy-to-implement, full-featured, open-source library for Next.js applications.

Install NextAuth.js

First, install next-auth and @prisma/client in your Next.js project:

npm install next-auth @prisma/client

Configure NextAuth.js

Next, create a [...nextauth].js file inside the pages/api/auth directory:

import NextAuth from 'next-auth'
import Providers from 'next-auth/providers'

export default NextAuth({
  providers: [
    Providers.GitHub({
      clientId: process.env.GITHUB_ID,
      clientSecret: process.env.GITHUB_SECRET
    })
  ],
})

In this file, we are importing the necessary modules and exporting a default function that uses the NextAuth function to configure our authentication provider.

Code Examples

Below is an example of how you can protect your pages and API routes.

Protecting Pages

You can use the useSession hook from next-auth/client to protect your pages:

import { useSession } from 'next-auth/client'

export default function Page() {
  const [ session, loading ] = useSession()

  if (loading) return null

  if (!loading && !session) return <p>Access Denied</p>

  return (
    <>
      <h1>Protected Page</h1>
      <p>You can view this page because you are signed in.</p>
    </>
  )
}

Protecting API Routes

You can also protect your API routes by using the getSession function from next-auth/client:

import { getSession } from 'next-auth/client'

export default async (req, res) => {
  const session = await getSession({ req })

  if (session) {
    res.send({ content: 'This is protected content. You can access this content because you are signed in.' })
  } else {
    res.send({ error: 'You must be sign in to view this content' })
  }
}

Summary

In this tutorial, we've learned about authentication, its importance, and how to integrate it into Next.js applications using NextAuth.js. We have also seen examples of how to protect pages and API routes.

Next Steps

• Explore more about NextAuth.js and its providers.
• Try to implement different authentication methods like email/password, social login etc.

Additional Resources

• NextAuth.js Documentation

Practice Exercises

Exercise 1

Implement authentication in a Next.js application using NextAuth.js and Google as authentication provider.

Exercise 2

Create a Next.js application where only authenticated users can view certain pages.

Exercise 3

Create a Next.js application where only authenticated users can access certain API routes.

Solutions and Explanations

Please refer to the code examples given above and the NextAuth.js documentation for solutions to these exercises.