name: nextauth description: >- Configure NextAuth.js v5 authentication with OAuth providers and Prisma adapter. Use when setting up login/logout, protecting routes, accessing sessions in components, adding OAuth providers, or troubleshooting authentication issues. license: MIT compatibility: [Claude Code] metadata: author: ftcmetrics version: "1.0.0" category: auth

NextAuth.js v5 Authentication Guide

NextAuth.js v5 (Auth.js) is the authentication library for FTC Metrics. It uses OAuth providers (Google, Discord, GitHub) with a Prisma database adapter for session persistence.

Quick Start

1. Install Dependencies

bun add next-auth@beta @auth/prisma-adapter

2. Create Auth Configuration

Create src/lib/auth.ts:

import NextAuth from "next-auth";
import { PrismaAdapter } from "@auth/prisma-adapter";
import Google from "next-auth/providers/google";
import Discord from "next-auth/providers/discord";
import GitHub from "next-auth/providers/github";
import { prisma } from "@ftcmetrics/db";

export const { handlers, auth, signIn, signOut } = NextAuth({
  adapter: PrismaAdapter(prisma),
  providers: [
    Google({
      clientId: process.env.GOOGLE_CLIENT_ID!,
      clientSecret: process.env.GOOGLE_CLIENT_SECRET!,
    }),
    Discord({
      clientId: process.env.DISCORD_CLIENT_ID!,
      clientSecret: process.env.DISCORD_CLIENT_SECRET!,
    }),
    GitHub({
      clientId: process.env.GITHUB_CLIENT_ID!,
      clientSecret: process.env.GITHUB_CLIENT_SECRET!,
    }),
  ],
  pages: {
    signIn: "/login",
    error: "/login",
  },
  callbacks: {
    async session({ session, user }) {
      if (session.user) {
        session.user.id = user.id;
      }
      return session;
    },
  },
  session: {
    strategy: "database",
  },
});

3. Create API Route Handler

Create src/app/api/auth/[...nextauth]/route.ts:

import { handlers } from "@/lib/auth";

export const { GET, POST } = handlers;

4. Add Session Provider

Create src/components/providers.tsx:

"use client";

import { SessionProvider } from "next-auth/react";

export function Providers({ children }: { children: React.ReactNode }) {
  return <SessionProvider>{children}</SessionProvider>;
}

Wrap your app in src/app/layout.tsx:

import { Providers } from "@/components/providers";

export default function RootLayout({ children }: { children: React.ReactNode }) {
  return (
    <html lang="en">
      <body>
        <Providers>{children}</Providers>
      </body>
    </html>
  );
}

Prisma Schema Requirements

Required models for NextAuth with database sessions:

model User {
  id            String    @id @default(cuid())
  name          String?
  email         String?   @unique
  emailVerified DateTime? @map("email_verified")
  image         String?
  createdAt     DateTime  @default(now()) @map("created_at")
  updatedAt     DateTime  @updatedAt @map("updated_at")

  accounts Account[]
  sessions Session[]

  @@map("users")
}

model Account {
  id                String  @id @default(cuid())
  userId            String  @map("user_id")
  type              String
  provider          String
  providerAccountId String  @map("provider_account_id")
  refresh_token     String? @db.Text
  access_token      String? @db.Text
  expires_at        Int?
  token_type        String?
  scope             String?
  id_token          String? @db.Text
  session_state     String?

  user User @relation(fields: [userId], references: [id], onDelete: Cascade)

  @@unique([provider, providerAccountId])
  @@map("accounts")
}

model Session {
  id           String   @id @default(cuid())
  sessionToken String   @unique @map("session_token")
  userId       String   @map("user_id")
  expires      DateTime

  user User @relation(fields: [userId], references: [id], onDelete: Cascade)

  @@map("sessions")
}

Environment Variables

Add to .env:

# NextAuth
AUTH_SECRET="generate-with-openssl-rand-base64-32"

# Google OAuth
GOOGLE_CLIENT_ID="your-google-client-id"
GOOGLE_CLIENT_SECRET="your-google-client-secret"

# Discord OAuth
DISCORD_CLIENT_ID="your-discord-client-id"
DISCORD_CLIENT_SECRET="your-discord-client-secret"

# GitHub OAuth
GITHUB_CLIENT_ID="your-github-client-id"
GITHUB_CLIENT_SECRET="your-github-client-secret"

Generate AUTH_SECRET:

openssl rand -base64 32

Session Management Patterns

Server Components (Recommended)

Use the auth() function directly in Server Components:

import { auth } from "@/lib/auth";
import { redirect } from "next/navigation";

export default async function DashboardPage() {
  const session = await auth();

  if (!session?.user) {
    redirect("/login");
  }

  return <div>Welcome, {session.user.name}</div>;
}

Protected Layouts

Protect entire route groups with layout-level auth:

import { auth } from "@/lib/auth";
import { redirect } from "next/navigation";

export default async function ProtectedLayout({
  children,
}: {
  children: React.ReactNode;
}) {
  const session = await auth();

  if (!session?.user) {
    redirect("/login");
  }

  return <>{children}</>;
}

Client Components

Use the useSession hook in Client Components:

"use client";

import { useSession, signOut } from "next-auth/react";

export function UserMenu() {
  const { data: session, status } = useSession();

  if (status === "loading") {
    return <div>Loading...</div>;
  }

  if (!session?.user) {
    return <a href="/login">Sign in</a>;
  }

  return (
    <div>
      <img src={session.user.image} alt={session.user.name} />
      <span>{session.user.name}</span>
      <button onClick={() => signOut({ callbackUrl: "/" })}>
        Sign out
      </button>
    </div>
  );
}

Sign In with Providers

"use client";

import { signIn } from "next-auth/react";

export function LoginButtons() {
  return (
    <div>
      <button onClick={() => signIn("google", { callbackUrl: "/dashboard" })}>
        Continue with Google
      </button>
      <button onClick={() => signIn("discord", { callbackUrl: "/dashboard" })}>
        Continue with Discord
      </button>
      <button onClick={() => signIn("github", { callbackUrl: "/dashboard" })}>
        Continue with GitHub
      </button>
    </div>
  );
}

Adding User ID to Session

The session callback extends the session with the database user ID:

callbacks: {
  async session({ session, user }) {
    if (session.user) {
      session.user.id = user.id;
    }
    return session;
  },
},

Access the user ID in components:

// Server Component
const session = await auth();
const userId = session?.user?.id;

// Client Component
const { data: session } = useSession();
const userId = session?.user?.id;

OAuth Provider Setup

Google

Go to Google Cloud Console
Create OAuth 2.0 credentials
Add authorized redirect URI: http://localhost:3000/api/auth/callback/google

Discord

Go to Discord Developer Portal
Create application and OAuth2 credentials
Add redirect URI: http://localhost:3000/api/auth/callback/discord

GitHub

Go to GitHub Developer Settings
Create OAuth App
Add callback URL: http://localhost:3000/api/auth/callback/github

Common Pitfalls

Session Not Available

Ensure SessionProvider wraps your entire app in the root layout
Ensure the API route exists at app/api/auth/[...nextauth]/route.ts

User ID Missing from Session

Add the session callback to include user.id
When using database strategy, user info comes from the user parameter, not token

Database Session Issues

Ensure Prisma schema matches NextAuth requirements exactly
Use onDelete: Cascade on relations to handle user deletion
Run prisma migrate dev after schema changes

OAuth Callback Errors

Verify redirect URIs match exactly in provider console
Include the full path: /api/auth/callback/[provider]
For production, update URIs to use HTTPS and your domain

AUTH_SECRET Missing

Generate with openssl rand -base64 32
Required in production, auto-generated in development

TypeScript Type Extensions

Extend session types in src/types/next-auth.d.ts:

import { DefaultSession } from "next-auth";

declare module "next-auth" {
  interface Session {
    user: {
      id: string;
    } & DefaultSession["user"];
  }
}

File Structure Reference

packages/web/src/
  lib/
    auth.ts                           # NextAuth configuration
  components/
    providers.tsx                     # SessionProvider wrapper
  app/
    api/auth/[...nextauth]/
      route.ts                        # API route handler
    layout.tsx                        # Root layout with Providers
    login/
      page.tsx                        # Login page (server)
      login-form.tsx                  # OAuth buttons (client)
    dashboard/
      layout.tsx                      # Protected layout
      page.tsx                        # Uses auth() for session

Authentification NextAuth.js v5

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