How to Implement Authentication in Next.js 14 With NextAuth.js, Shadcn/ui, react-hook-form, and Zod

A Comprehensive Guide: Credentials (Email and Password) Ensuring the security and privacy of users is more important than ever. Web authentication plays a crucial role in this aspect, serving as the first line of defense to protect users’ information and data. Today, we have tools like NextAuth.js that make our job much easier, allowing us to implement different types of authentication easily in our Next.js applications. In this series of tutorials, we are going to build a complete authentication system in Next.js 14, starting with the basics: authentication with email and password. What Is NextAuth.js (Auth.js)? Within the JavaScript ecosystem and, more specifically, in applications developed with Next.js, one of the most prominent libraries for handling authentication is NextAuth.js. This tool offers a simple and easy-to-implement solution for adding authentication to our applications. The best thing is its flexibility; it allows the integration of different authentication providers such as Google, Facebook, and Twitter, in addition to credential-based authentication, such as the classic email and password. Implementing Credentials Authentication Credential authentication is especially useful in applications where you need full control over the authentication process and storage of user credentials, or when you do not want to rely on external authentication providers. Setting Up Create a new Next.js project with the following command, and follow the steps indicated. We will use TypeScript and the folder. src/ npx create-next-app@latest 2. Install the dependencies needed in the project. This time, we’ll use ; you can use the package manager of your choice. pnpm pnpm install next-auth prisma react-hook-form zod, bcrypt For the UI, we’ll use Shadcn/ui. pnpm dlx shadcn-ui@latest init is an open-source database toolkit. We will use it to store user credentials. : prisma Authentication for Next.js. : next-auth a library that helps you validate forms in React. : react-hook-form a data validator. : zod to hash passwords. : bcrypt : a collection of reusable components. shadcn/ui 3. Create the following structure for the project: ... ├── prisma/ ... ├── src/ │ ├── actions/ │ │ └── auth-actions.tsx │ ├── app/ │ │ ├── api/auth/[...nextauth] │ │ │ └── route.ts │ │ ├── auth/ │ │ │ ├── signin │ │ │ │ └── page.tsx │ │ │ └── signup │ │ │ └── page.tsx │ │ │ ... │ ├── components/ │ │ ├── auth/ │ │ │ ├── auth-buttons.tsx │ │ │ ├── signin-form.tsx │ │ │ ├── signup-form.tsx │ │ │ └── user-nav.ts │ │ ├── ui/ │ │ │ ... │ │ ├── auth-provider.tsx │ │ ├── icons.tsx │ │ └── theme-provider.tsx │ ├── lib/ │ │ ├── prisma.ts │ │ ├── types.d.ts │ │ └── utils.ts │ ... ... Setting Up Prisma We’ll use Prisma to store and retrieve users in the database. Prisma allows the integration of different database types so you can use any database you need, we’ll use SQLite. . Initializing Prisma npx prisma init --datasource-provider sqlite This creates the prism folder with its schemas. Creating the models. To create the models, we’ll use the ones provided by and customize them a little bit as follows: @auth/prisma-adapter : prisma/schema.prisma generator client { provider = "prisma-client-js" output = "../../node_modules/.prisma/client" }

datasource db { provider = "sqlite" url = env("DATABASE_URL") }

... model User { id String @id @default(cuid()) username String password String email String @unique emailVerified DateTime? phone String? image String? } ... 3. Creating the first . migration npx prisma migrate dev --name first-migration With this command, more files have been created in the Prisma folder, and the database has been synchronized with the models. 4. Prisma client Finally, we create a Prisma Client. : lib/prisma.ts import { PrismaClient } from "@prisma/client";

const globalForPrisma = global as unknown as { prisma: PrismaClient; };

export const prisma = globalForPrisma.prisma || new PrismaClient();

if (process.env.NODE_ENV !== "production") globalForPrisma.prisma = prisma;

export default prisma; Setting Up NextAuth.js Creating variables. env # Secret key for NextAuth.js, used for encryption and session security. It should be a long, # random string unique to your application. NEXTAUTH_SECRET=XXX3B2CC28F123456C6934531CXXXXX

# Base URL for your Next.js app, used by NextAuth.js for redirects and callbacks. NEXTAUTH_URL=http://localhost:3000/ Creating the auth route. This path allows handling all authentication requests (such as login, logout, and vendor callbacks) on a single endpoint. src/app/api/auth/[...nextauth] Creating the providers. ... // Imports the Prisma User type for typing. import { User } from '@prisma/client'

// Configuration of authentication options for NextAuth. export const authOptions: AuthOptions = { ... // Defines authentication providers, in this case, only credentials. providers: [ CredentialsProvider({ name: 'Credentials', // Defines the required fields for authentication. credentials: { email: { label: 'Email', type: 'text' }, password: { label: 'Password', type: 'password' }, }, // Function to authenticate the user with the provided credentials. async authorize(credentials) { // Searches for the user in the database by email. const user = await prisma.user.findUnique({ where: { email: credentials?.email, }, })

// Checks if the user exists and if the password is correct. if (!user) throw new Error('User name or password is not correct')

if (!credentials?.password) throw new Error('Please Provide Your Password') const isPasswordCorrect = await bcrypt.compare(credentials.password, user.password)

if (!isPasswordCorrect) throw new Error('User name or password is not correct')

// Returns the user without including the password. const { password, ...userWithoutPass } = user return userWithoutPass }, }), ], }

// Exports the configured NextAuth handler to handle GET and POST requests. const handler = NextAuth(authOptions) export { handler as GET, handler as POST } 4. Creating the Auth Provider. : src/components/auth-provider.tsx 'use client'

import { SessionProvider } from 'next-auth/react'

export default function AuthProvider({ children }: { children: React.ReactNode }) { return {children} } This component acts as a session provider for Next.js applications that use NextAuth for authentication. Wrapping components or pages in this provider grants them access to the session context, allowing child components to use NextAuth hooks and functionality, such as , to access or modify the state of the user’s current session. useSession : src/app/layout.tsx /* All imports */ export default function RootLayout({ children }: { children: React.ReactNode }) { return ( {children} ) } Setting Up the UI With Shadcn/ui Installing shadcn/ui following the . documentation (step 2) Would you like to use TypeScript (recommended)? yes Which style would you like to use? › Default Which color would you like to use as base color? › Slate Where is your global CSS file? › src/app/globals.css Do you want to use CSS variables for colors? › yes Are you using a custom tailwind prefix eg. tw-? Leave blank Where is your tailwind.config.js located? › tailwind.config.js Configure the import alias for components: › @/components Configure the import alias for utils: › @/lib/utils Are you using React Server Components? › yes You can use the theme of your choice. 2. Implementing Dark mode : src/app/layout.tsx /* All imports */ export default function RootLayout({ children }: { children: React.ReactNode }) { return ( {children}

) } 2. Installing the following shadcn/ui components: pnpm dlx shadcn-ui@latest add avatar button dropdown-menu form input label tabs toast Creating Authentication Components : src/components/auth-buttons.tsx 'use client'

import Link from 'next/link' import { signIn, useSession } from 'next-auth/react'

import { Button } from '../ui/button' import { UserNav } from './user-nav'

export default function AuthButtons() { // Use the useSession hook to access session data const { data: session } = useSession()

return ( {session && session.user ? ( ) : ( <> signIn()} > Sign In Sign Up )} ) } This component dynamically displays authentication options based on the user's session status. If the user is logged in, it shows user-specific navigation. Otherwise, it offers buttons to sign in or sign up, making use of Next.js's routing and NextAuth's authentication capabilities for a smooth user experience. Modify the home page, and add the auth buttons. This is how it looks: : src/components/auth/signup-form.tsx 'use client'

/* all imports */

// Function to register a new user import { registerUser } from '@/actions/auth-actions'

// Define the validation schema for the signup form using Zod const formSchema = z .object({ username: z .string({ required_error: 'Username is required', }) .min(2, 'User name must have at least 2 characters') .max(12, 'Username must be up to 12 characters') .regex(new RegExp('^[a-zA-Z0-9]+$'), 'No special characters allowed!'), email: z.string({ required_error: 'Email is required' }).email('Please enter a valid email address'), password: z .string({ required_error: 'Password is required' }) .min(6, 'Password must have at least 6 characters') .max(20, 'Password must be up to 20 characters'), confirmPassword: z .string({ required_error: 'Confirm your password is required' }) .min(6, 'Password must have at least 6 characters') .max(20, 'Password must be up to 20 characters'), }) .refine(values => values.password === values.confirmPassword, { message: "Password and Confirm Password doesn't match!", path: ['confirmPassword'], })

// Type inference for form inputs based on the Zod schema type InputType = z.infer

export function SignUpForm() { const [isLoading, setIsLoading] = useState(false) const { toast } = useToast() // Hook to show toast notifications

// Initialize form handling with React Hook Form and Zod for validation const form = useForm ({ resolver: zodResolver(formSchema), })

// Handles form submission async function onSubmit(values: InputType) { try { setIsLoading(true) const { confirmPassword, ...user } = values // Exclude confirmPassword from data to be sent

const response = await registerUser(user) // Register the user if ('error' in response) { toast({ title: 'Something went wrong!', description: response.error, variant: 'success', }) } else { toast({ title: 'Account Created!', description: 'Your account has been created successfully! You can now login.', }) } } catch (error) { console.error(error) toast({ title: 'Something went wrong!', description: "We couldn't create your account. Please try again later!", variant: 'destructive', }) } finally { setIsLoading(false) } }

return ( // Each FormField validates and displays an input ( )} />

// Repeated structure for email, password, and confirmPassword with respective validations and icons {isLoading && } // Show loading icon if isLoading is true Sign Up ) } This component encapsulates a user registration form, utilizing react-hook-form for form state management and Zod for schema validation. While this is not a tutorial on these technologies, we are only using the basics of them, if you have more questions, you can go to their documentation. I have added some more styles to the page, and it looks like this: : src/actions/auth-action/ts 'use server'

/* all imports */

export async function registerUser(user: Omit ) { try { // Attempt to create a new user record in the database const result = await prisma.user.create({ data: { ...user, // Hash the password before storing it password: await bcrypt.hash(user.password, 10), }, })

return result } catch (error) { console.log(error) // Handle known request errors from Prisma if (error instanceof Prisma.PrismaClientKnownRequestError) { // Check for unique constraint failure (e.g., email already exists) if (error.code === 'P2002') { return { error: 'Email already exists.' } } }

// Return a generic error message for any other errors return { error: 'An unexpected error occurred.' } } } function is designed to securely register a new user by creating a record in the database with the provided user information, excluding fields like , , , and . registerUser id phone emailVerified image It uses bcrypt to hash the user's password for secure storage. To test our sign-up and validate that the user is registering correctly, we need to add some callbacks; these are functions that allow you to customize the behavior of authentication and session management. : src/app/api/auth/[...nextauth] ...

export const authOptions: AuthOptions = { // Define custom pages for authentication flow pages: { signIn: '/auth/signin', // Custom sign-in page }, // Configure session management to use JSON Web Tokens (JWT) session: { strategy: 'jwt', }, // JWT configuration, including secret for token signing jwt: { secret: process.env.NEXTAUTH_SECRET, // Secret used to sign the JWT, stored in environment variables },

...

// Callbacks for customizing JWT and session behaviors callbacks: { // Callback to modify the JWT content. Adds user information if available. async jwt({ token, user }) { if (user) token.user = user as User // Cast user object to User type and assign to token return token },

// Callback to modify session content. Adds user information to the session. async session({ token, session }) { session.user = token.user // Assign user information from token to session return session }, }, } ... Callback : this callback is executed whenever a JSON Web Token (JWT) is created or updated during the authentication lifecycle. It allows you to modify the contents of the token before it is signed and sent to the client or stored on the server. jwt This is useful for adding additional information to the token, which may be relevant to your application logic. Callback : this callback is called each time the session data is read, such as during server-side rendering or in protected API requests. It allows session data to be modified before it is sent to the client. session This is especially useful for adding or modifying session data based on information stored in the JWT or other criteria. Finally, we need to extend the NextAuth and type definitions to include additional user information. Session JWT : src/lib/types.d.ts import { User } from '@prisma/client'

declare module 'next-auth' { interface Session { user: User } }

declare module 'next-auth/jwt' { interface JWT { user: User } } Now, if we fill out the form and submit it, we will be able to see the success toast. To verify that the user was saved in the database, we can see graphically the tables created by Prisma with the following command: nxp prisma studio We will have available the following route http://localhost:5555 : src/components/auth/user-nav.tsx /* all imports */

interface Props { user: User // Expect a user object of type User from Prisma client }

export function UserNav({ user }: Props) { return ( UU {user.username}

{user.email}

Sign Out ) } : src/components/auth/signin-form.tsx /* all imports */

// Schema definition for form validation using Zod const formSchema = z.object({ email: z.string({ required_error: 'Please enter your email' }).email('Please enter a valid email address'), password: z.string({ required_error: 'Please enter your password', }), })

// Type inference for form inputs based on the Zod schema type InputType = z.infer

// Props definition, optionally including a callback URL interface Props { callbackUrl?: string }

export function SignInForm({ callbackUrl }: Props) { const [isLoading, setIsLoading] = useState(false) const { toast } = useToast()

const router = useRouter() // Hook to control routing

const form = useForm ({ resolver: zodResolver(formSchema), // Set up Zod as the form validation resolver })

// Function to handle form submission async function onSubmit(values: InputType) { try { setIsLoading(true)

// Attempt to sign in using the 'credentials' provider const response = await signIn('credentials', { redirect: false, // Prevent automatic redirection email: values.email, password: values.password, })

// Handle unsuccessful sign in attempts if (!response?.ok) { toast({ title: 'Something went wrong!', description: response?.error, variant: 'destructive', }) return }

toast({ title: 'Welcome back! ', description: 'Redirecting you to your dashboard!', }) router.push(callbackUrl ? callbackUrl : '/') // Redirect to the callback URL or home page } catch (error) { toast({ title: 'Something went wrong!', description: "We couldn't create your account. Please try again later!", variant: 'destructive', }) } finally { setIsLoading(false) } }

return ( ( )} /> {/* Password field */} {/* Similar structure to email field, customized for password input */} {isLoading && } // Show loading spinner when processing Sign In ) } 🎉 It's done! We’ve finished implementing a basic authentication with NextAuth.js. There are still many things to do to have a complete authentication system, and we will cover them in the next tutorials. 🔗 Repo here Conclusion In summary, we have explored how to implement and customize an authentication system in Next.js using NextAuth, how to extend sessions and JWTs to enrich user management, and how to handle forms with effective validation using react-hook-form and Zod. Want to connect with the Author? Love connecting with friends all around the world on . 𝕏 Also published here