In the auth.ts file, use the authorize function to manage the authentication logic. Validate the email and password using zod before checking if the user exists in the database.

auth.ts

import NextAuth from 'next-auth';
import { authConfig } from './auth.config';
import Credentials from 'next-auth/providers/credentials';
import { z } from 'zod';

export const { auth, signIn, signOut } = NextAuth({
  ...authConfig,
  providers: [
    Credentials({
      async authorize(credentials) {
        const parsedCredentials = z
          .object({ email: z.string().email(), password: z.string().min(6) })
          .safeParse(credentials);
      },
    }),
  ],
});

2. Fetching User from Database

After validating credentials, create a getUser function that queries the user from the database using Postgres.

auth.ts

import NextAuth from 'next-auth';
import Credentials from 'next-auth/providers/credentials';
import { authConfig } from './auth.config';
import { z } from 'zod';
import { sql } from '@vercel/postgres';
import type { User } from '@/app/lib/definitions';

async function getUser(email: string): Promise<User | undefined> {
  try {
    const user = await sql<User>`SELECT * FROM users WHERE email=${email}`;
    return user.rows[0];
  } catch (error) {
    console.error('Failed to fetch user:', error);
    throw new Error('Failed to fetch user.');
  }
}

export const { auth, signIn, signOut } = NextAuth({
  ...authConfig,
  providers: [
    Credentials({
      async authorize(credentials) {
        const parsedCredentials = z
          .object({ email: z.string().email(), password: z.string().min(6) })
          .safeParse(credentials);

        if (parsedCredentials.success) {
          const { email, password } = parsedCredentials.data;
          const user = await getUser(email);
          if (!user) return null;
        }

        return null;
      },
    }),
  ],
});

3. Checking Passwords Match

Call bcrypt.compare to check if the entered password matches the one stored in the database.

auth.ts

// ...
import type { User } from '@/app/lib/definitions';
import bcrypt from 'bcrypt';

async function getUser(email: string): Promise<User | undefined> {
  // ...
}

export const { auth, signIn, signOut } = NextAuth({
  ...authConfig,
  providers: [
    Credentials({
      async authorize(credentials) {
        const parsedCredentials = z
          .object({ email: z.string().email(), password: z.string().min(6) })
          .safeParse(credentials);

        if (parsedCredentials.success) {
          const { email, password } = parsedCredentials.data;
          const user = await getUser(email);
          if (!user) return null;

          const passwordsMatch = await bcrypt.compare(password, user.password);

          if (passwordsMatch) return user;
        }

        console.log('Invalid credentials');
        return null;
      },
    }),
  ],
});

In Practice

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Секція 7. Розділ 6

Зміст курсу

Next.js 14

1. Introduction

Welcome Project Overview Course Prerequisites How the Course Works

2. Basic Concepts

Project Set Up Project File-Folder Strcture Styling Approaches Adding the Global CSS File Tailwind Styling CSS Modules Conditionally Applying Styles Custom Google Fonts Challenge: Adding Custom Google Font Images

3. Pages and Layouts

How Routing Works Challenge: Creating Page Creating a Common Layout Navigation Optimization Creating Active Links

4. Deployment and Database

Accounts Set Up Project Deployment Project Database Data Population

5. Working with Data

How to Fetch Data Working with the Dashboard Page Practice and Challenge: Retrieving Data Dynamic vs Static Rendering Loaders Specific Parts Loaders Challenge: Skeleton Loader Grouping Components for Loaders

6. Advanced Features

Invoices Page Search Functionality Pagination Server Actions Creating Item Updating Item Deleting Item Challenge: Form Validation

7. Authentication

Understanding Authentication Login Route NextAuth.js Authentication Configuration & Route Protection Password Hashing & Credentials Sign-in Functionality Connecting UI & Functionality Logout Functionality What's Next?

Next.js 14

Sign-in Functionality

We focus on the sign in functionality.

Back to the Project

1. Handling Authentication Logic

In the auth.ts file, use the authorize function to manage the authentication logic. Validate the email and password using zod before checking if the user exists in the database.

auth.ts

import NextAuth from 'next-auth';
import { authConfig } from './auth.config';
import Credentials from 'next-auth/providers/credentials';
import { z } from 'zod';

export const { auth, signIn, signOut } = NextAuth({
  ...authConfig,
  providers: [
    Credentials({
      async authorize(credentials) {
        const parsedCredentials = z
          .object({ email: z.string().email(), password: z.string().min(6) })
          .safeParse(credentials);
      },
    }),
  ],
});

2. Fetching User from Database

After validating credentials, create a getUser function that queries the user from the database using Postgres.

auth.ts

import NextAuth from 'next-auth';
import Credentials from 'next-auth/providers/credentials';
import { authConfig } from './auth.config';
import { z } from 'zod';
import { sql } from '@vercel/postgres';
import type { User } from '@/app/lib/definitions';

async function getUser(email: string): Promise<User | undefined> {
  try {
    const user = await sql<User>`SELECT * FROM users WHERE email=${email}`;
    return user.rows[0];
  } catch (error) {
    console.error('Failed to fetch user:', error);
    throw new Error('Failed to fetch user.');
  }
}

export const { auth, signIn, signOut } = NextAuth({
  ...authConfig,
  providers: [
    Credentials({
      async authorize(credentials) {
        const parsedCredentials = z
          .object({ email: z.string().email(), password: z.string().min(6) })
          .safeParse(credentials);

        if (parsedCredentials.success) {
          const { email, password } = parsedCredentials.data;
          const user = await getUser(email);
          if (!user) return null;
        }

        return null;
      },
    }),
  ],
});

3. Checking Passwords Match

Call bcrypt.compare to check if the entered password matches the one stored in the database.

auth.ts

// ...
import type { User } from '@/app/lib/definitions';
import bcrypt from 'bcrypt';

async function getUser(email: string): Promise<User | undefined> {
  // ...
}

export const { auth, signIn, signOut } = NextAuth({
  ...authConfig,
  providers: [
    Credentials({
      async authorize(credentials) {
        const parsedCredentials = z
          .object({ email: z.string().email(), password: z.string().min(6) })
          .safeParse(credentials);

        if (parsedCredentials.success) {
          const { email, password } = parsedCredentials.data;
          const user = await getUser(email);
          if (!user) return null;

          const passwordsMatch = await bcrypt.compare(password, user.password);

          if (passwordsMatch) return user;
        }

        console.log('Invalid credentials');
        return null;
      },
    }),
  ],
});

In Practice

Все було зрозуміло?

Секція 7. Розділ 6