Summary
This chapter demonstrates how to define a server action for handling credential-based sign-in with validation and error handling, and how to integrate that action into a React form component using useFormState to manage form submission and feedback.

General domain of usage
User authentication

Let's ensure that the login functionality is working correctly.

### 1. Create the authenticate action
In the `actions.ts` file, establish a new action named `authenticate`. This action should incorporate the `signIn` function from `auth.ts`:

### Modify login form
Within the `login-form.tsx `component, leverage React's `useFormState` to invoke the server action.

Learn to build modern, high-performance web applications using Next.js. Set up projects with structured layouts, styling, and routing for seamless navigation. Fetch and display data efficiently while optimizing rendering and performance. Implement advanced features like pagination, CRUD operations, and global search for dynamic web apps. Deploy your Next.js projects and connect them with databases, and add authentication to protect user data.

Let's discuss what you need to learn before diving into the Next.js framework, what to expect from this course, and what you'll build.

We will set up the project, inspect ways to add styling to our app and cover visual aspects such as images, fonts, pages, and layouts.

Learn how to easily create and manage a new view for your app and navigate through all pages seamlessly with an incorporated routing system.

Deploy the Next.js app using GitHub and Vercel accounts. Additionally, establish a database to supply the app with the necessary data.

Consider how to obtain and show data to the user clearly and efficiently.

Discover how to implement modern web features such as pagination, CRUD operations, global search, form validation, and more.

Authentication implementation in Next.js.

Connecting the UI with Authentication Logic

Back to the Project

1. Create the authenticate action

Modify login form

In Practice