Authentication and authorization are key components in any modern web application. In this chapter, we will learn how to implement authentication and authorization in a Next.js 13 application using the App Router. We will see how to protect routes and efficiently manage user sessions.

Authentication with Next.js

To implement authentication, we can use several libraries. One of the most common is NextAuth.js, which offers a ready-made solution to handle different authentication providers like Google, GitHub, among others.

Configuring NextAuth.js

First, we need to install NextAuth.js in our project:

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After installing the library, we can configure the authentication provider. Below is how to configure NextAuth.js to use authentication with Google.

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In this case, we have set up the Google provider and created the API to handle authentication. Remember to store the credentials in environment variables.

Protecting a Route

To protect a route, we can use the useSession hook that NextAuth.js provides to verify if the user is authenticated. If the user is not authenticated, we can redirect them to the login page.

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This approach is ideal for protecting routes that should only be accessible to authenticated users.

Role-Based Authorization

Authorization goes a step beyond authentication, as it involves checking if the user has the necessary permissions to access certain resources. For example, we might have an application with different user roles, such as "admin" and "user", and only allow administrators to access certain routes.

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This example demonstrates how to implement role-based authorization, ensuring that only authorized users can access certain pages.

Session Management

NextAuth.js automatically manages sessions, but you can also customize their duration and behavior. For example, you can define the session lifespan in the configuration file:

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Such configurations allow you to tailor the user experience and ensure session security.

Conclusion

Implementing authentication and authorization in Next.js 13 using the App Router is a relatively straightforward process thanks to tools like NextAuth.js. In this chapter, we have seen how to protect routes, manage user roles, and handle sessions. These concepts are essential to ensure that only authorized users can access the private parts of the application.