MongoDB authentication integration in Next.js with NextAuth.js enhances the security of web applications. Integrating authentication in a Next.js application using MongoDB as the database can be efficiently achieved with the NextAuth.js library. NextAuth.js is a complete open-source authentication solution for Next.js applications that supports various sign-in methods, including OAuth, Email, and Credentials.

Prerequisites

• NodeJS
• MongoDB
• NextJS

Authentication types in NextJS

Next.js supports various authentication methods. Here are the main ones:

• Credentials-based login (Email + Password): A standard choice for web applications is where users log in with an email and password. This method is familiar and easy to implement. It requires robust security measures to protect against threats like phishing attacks.
• OAuth Providers: This approach allows users to log in with their existing accounts on platforms like Google, GitHub, or Facebook.
• Custom Authentication: This method allows users to create their own authentication methods, such as token-based login. For example, when a user logs in successfully, their token is stored in local storage. The session for the user is then managed by comparing the token using JWT (JSON Web Token).

Steps to implement Authentication

Step 1: Create a nextJS application by using this command

npx create-next-app myapp

Step 2: Navigate to project directory

cd myapp

Step 3: Install the necessary packages/libraries in your project using the following commands.

npm install next-auth  mongoose

Project Structure:

The updated dependencies in package.json file will look like:

"dependencies": {
    "next": "latest",
    "react": "latest",
    "react-dom": "latest",
    "next-auth": "^4.0.0",
    "@next-auth/mongodb-adapter": "^0.0.0",
    "mongodb": "^4.0.0"
  }

Steps for MongoDB connection

Step 1: Create a "libs/mongodb.js" file in your project folder

Step 2: Add these code to your "mongodb.js" file.

Note: Ensure your .env contains the MONGODB_URI and NODE_ENV

import { MongoClient } from 'mongodb';

const client = new MongoClient(process.env.MONGODB_URI, {
  useNewUrlParser: true,
  useUnifiedTopology: true,
});

let clientPromise;

if (process.env.NODE_ENV === 'development') {
  if (!global._mongoClientPromise) {
    global._mongoClientPromise = client.connect();
  }
  clientPromise = global._mongoClientPromise;
} else {
  clientPromise = client.connect();
}

export default clientPromise;

Example: Implementation of MongoDB Authentication In NextJS Using NextAuth.Js

import NextAuth from "next-auth/next";
import CredentialsProvider from "next-auth/providers/credentials";
import { clientPromise } from '../../../util/db';

export const authOptions = {
    providers: [
        CredentialsProvider({
            name: "credentials",
            credentials: {},
            async authorize(credentials) {
                const db = await connectToDatabase();
                const users = db.collection('users');
                const user = await users.findOne({
                    email: credentials.email,
                    password: credentials.password,
                });

                if (user) {
                    return Promise.resolve(user);
                }
                return Promise.resolve(null);
            },
  ],
    session: {
        strategy: "jwt",
    },
    secret: process.env.NEXTAUTH_SECRET,
    pages: {
        signIn: "/login",
    },
};

const handler = NextAuth(authOptions);

export { handler as GET, handler as POST };

import NextAuth from 'next-auth';
import Providers from 'next-auth/providers';
import { MongoClient } from 'mongodb';
import GoogleProvider from "next-auth/providers/google"

export default NextAuth({
    providers: [
        GoogleProvider({
            clientId: process.env.GOOGLE_CLIENT_ID,
            clientSecret: process.env.GOOGLE_CLIENT_SECRET,
            profile(profile) {
                return {
                    // Return all the profile information you need.
                    // The only truly required field is `id`
                    // to be able identify the account when added to a database
                }
            },
        })
    ],
    session: {
        jwt: true,
    },
    callbacks: {
        async session({ session, token }) {
            session.user.id = token.sub;
            return session;
        },
    },
    database: process.env.MONGODB_URI,
});

.env File structure:

Output:

Conclusion

In this article, we've set up authentication in a Next.js application using MongoDB and NextAuth.js. This includes configuring MongoDB connection, setting up NextAuth.js with MongoDB adapter, creating a sign-in page, and protecting pages. This setup provides a robust foundation for handling authentication in your Next.js applications with MongoDB.