フルスタックアプリの構築

Fullstack App: Task Manager

Project Init & Database Setup

// prisma/schema.prisma
generator client {
  provider = "prisma-client-js"
}

datasource db {
  provider = "sqlite" // or "postgresql", "mysql"
  url      = env("DATABASE_URL")
}

model User {
  id        String    @id @default(cuid())
  email     String    @unique
  name      String?
  password  String // Hashed password
  tasks     Task[]
}

model Task {
  id        String    @id @default(cuid())
  title     String
  completed Boolean   @default(false)
  userId    String
  user      User      @relation(fields: [userId], references: [id])
  createdAt DateTime  @default(now())
  updatedAt DateTime  @updatedAt
}

Implementing NextAuth.js

// app/api/auth/[...nextauth]/route.ts
import NextAuth from "next-auth";
import CredentialsProvider from "next-auth/providers/credentials";
import { PrismaAdapter } from "@auth/prisma-adapter";
import { PrismaClient } from "@prisma/client";
import bcrypt from "bcrypt";

const prisma = new PrismaClient();

const handler = NextAuth({
  adapter: PrismaAdapter(prisma),
  providers: [
    CredentialsProvider({
      name: "Credentials",
      credentials: {
        email: { label: "Email", type: "text" },
        password: { label: "Password", type: "password" }
      },
      async authorize(credentials) {
        if (!credentials?.email || !credentials?.password) return null;

        const user = await prisma.user.findUnique({
          where: { email: credentials.email }
        });

        if (!user || !(await bcrypt.compare(credentials.password, user.password))) {
          return null;
        }
        return { id: user.id, email: user.email, name: user.name };
      },
    }),
  ],
  session: { strategy: "jwt" },
  callbacks: {
    jwt: async ({ token, user }) => {
      if (user) {
        token.id = user.id;
        token.email = user.email;
      }
      return token;
    },
    session: async ({ session, token }) => {
      if (token) {
        session.user.id = token.id as string;
        session.user.email = token.email;
      }
      return session;
    },
  },
  pages: {
    signIn: "/auth/signin",
  },
});

export { handler as GET, handler as POST };

Displaying User Tasks (RSC)

// app/dashboard/page.tsx
import { getServerSession } from "next-auth";
import { authOptions } from "@/app/api/auth/[...nextauth]/route"; // Adjust path
import { PrismaClient } from "@prisma/client";
import TaskList from "./TaskList"; // This will be a Client Component

const prisma = new PrismaClient();

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

  if (!session || !session.user?.id) {
    return <p>Please sign in to view your tasks.</p>;
  }

  const tasks = await prisma.task.findMany({
    where: { userId: session.user.id },
    orderBy: { createdAt: "desc" },
  });

  return (
    <div>
      <h1>Welcome, {session.user.name || session.user.email}!</h1>
      <h2>Your Tasks</h2>
      <TaskList initialTasks={tasks} />
    </div>
  );
}

Adding Tasks with Server Actions

// app/actions/task-actions.ts
"use server";

import { revalidatePath } from "next/cache";
import { getServerSession } from "next-auth";
import { authOptions } from "@/app/api/auth/[...nextauth]/route";
import { PrismaClient } from "@prisma/client";

const prisma = new PrismaClient();

export async function addTask(formData: FormData) {
  const session = await getServerSession(authOptions);

  if (!session || !session.user?.id) {
    throw new Error("Unauthorized");
  }

  const title = formData.get("title") as string;
  if (!title || title.trim() === "") {
    throw new Error("Task title cannot be empty.");
  }

  await prisma.task.create({
    data: {
      title,
      userId: session.user.id,
    },
  });

  revalidatePath("/dashboard"); // Revalidate dashboard to show new task
}

Interactive Task Management (RCC)

// app/dashboard/TaskList.tsx (Client Component)
"use client";

import { useState } from "react";
// Assume toggleTaskCompletion is another server action
import { toggleTaskCompletion } from "@/app/actions/task-actions"; 

export default function TaskList({ initialTasks }) {
  const [tasks, setTasks] = useState(initialTasks);

  const handleToggle = async (taskId: string, currentStatus: boolean) => {
    // Optimistic UI update
    setTasks(tasks.map(task =>
      task.id === taskId ? { ...task, completed: !currentStatus } : task
    ));
    try {
      await toggleTaskCompletion(taskId, !currentStatus);
    } catch (error) {
      console.error("Failed to toggle task:", error);
      // Revert if error
      setTasks(initialTasks); // Revert to initial state on error
    }
  };

  return (
    <ul>
      {tasks.map(task => (
        <li key={task.id}>
          <input
            type="checkbox"
            checked={task.completed}
            onChange={() => handleToggle(task.id, task.completed)}
          />
          <span style={{ textDecoration: task.completed ? "line-through" : "none" }}>
            {task.title}
          </span>
        </li>
      ))}
    </ul>
  );
}

Protecting Routes with Middleware

// middleware.ts
import { withAuth } from "next-auth/middleware";
import { NextResponse } from "next/server";

export default withAuth(
  // `withAuth` augments the Next.js request with the user's token.
  function middleware(req) {
    const { pathname } = req.nextUrl;
    // Example: Only allow authenticated users to access /dashboard
    if (pathname.startsWith("/dashboard") && !req.nextauth.token) {
      return NextResponse.redirect(new URL("/auth/signin", req.url));
    }
    // Allow access to public pages or authenticated pages
    return NextResponse.next();
  },
  {
    callbacks: {
      authorized: ({ token }) => !!token, // Only allow if token exists
    },
    pages: {
      signIn: "/auth/signin",
    },
  }
);

export const config = {
  matcher: ["/dashboard/:path*", "/api/protected/:path*"], // Apply middleware to these paths
};

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