Next.js 15 Fullstack (App Router + Server Actions) · Ders

Yolları ve Verileri Koruma

Kullanıcının kimlik doğrulama durumuna göre belirli yolları ve verileri korumak için ara katman yazılımı ve sunucu tarafı denetimleri uygulayın.

Yolları ve Verileri Koruma, CoddyKit'te ücretsiz bir Next.js 15 Fullstack (App Router + Server Actions) dersidir. Bu, 6 dersinin 3. dersidir. Aşağıdan dersin tamamını ücretsiz okuyabilir, sonra tarayıcıda yerleşik kod editörü ve 7/24 yapay zeka koçu ile uygulamalı olarak pratik yapabilirsin. Bu, Next.js 15 Fullstack (App Router + Server Actions) öğrenme yolunun bir parçasıdır ve ilerlemeniz web ve CoddyKit uygulaması arasında senkronize olur. Next.js 15 Fullstack (App Router + Server Actions) kursu toplamda 6 dersten oluşur.

Bu dersin bazı bölümleri henüz çevrilmemiş olup İngilizce olarak gösterilmektedir.

Why Protect Routes & Data?

In any application, not all information or features should be accessible to everyone. Protecting routes and data is crucial for security.

Route Protection: Prevents unauthorized users from even reaching certain pages (e.g., an admin dashboard).
Data Protection: Ensures users can only view or modify data they are authorized to access (e.g., a user's own profile, not someone else's).

This lesson explores how Next.js helps you enforce these rules on the server side.

Introducing Next.js Middleware

Next.js Middleware allows you to run code before a request is completed. It's like a gatekeeper for your application.

Middleware runs on the Edge Runtime, providing extremely fast execution. It can:

Redirect users to different pages.
Rewrite URLs.
Add/modify request or response headers.
Perform authentication checks.

Setting Up Middleware

To use middleware, create a file named middleware.ts (or .js) at the root of your project or within the src or app directory.

This file exports a function that receives the incoming request and returns a response.

import { NextResponse } from 'next/server';
import type { NextRequest } from 'next/server';

export function middleware(request: NextRequest) {
  // Your protection logic goes here
  console.log('Middleware executed for:', request.url);
  return NextResponse.next();
}

// Configure which paths the middleware applies to
export const config = {
  matcher: ['/dashboard/:path*', '/profile'],
};

Redirecting Unauthorized Users

A common use case for middleware is to redirect users who are not authenticated away from protected routes.

You can check for an authentication token or session cookie and, if missing, redirect them to a login page.

import { NextResponse } from 'next/server';
import type { NextRequest } from 'next/server';

export function middleware(request: NextRequest) {
  const isAuthenticated = request.cookies.has('session_token');
  const isLoginPage = request.nextUrl.pathname.startsWith('/login');

  if (!isAuthenticated && !isLoginPage) {
    const url = request.nextUrl.clone();
    url.pathname = '/login';
    return NextResponse.redirect(url);
  }

  return NextResponse.next();
}

export const config = {
  matcher: ['/dashboard/:path*', '/profile', '/settings'],
};

Server-Side Data Checks

While middleware protects routes, you also need to protect the data itself. A user might bypass client-side checks or try to access data via an API.

Always perform authorization checks directly within your Server Components, Server Actions, or API routes before fetching or mutating sensitive data.

Middleware: Route-level access control.
Server Components/Actions: Data-level access control.

Protecting Data in Server Components

Inside a Server Component, you can check the user's authentication status and roles to decide what data to fetch or display.

If the user isn't authorized, you might redirect them, show an 'Access Denied' message, or simply not render sensitive parts of the UI.

import { redirect } from 'next/navigation';
// Assume 'getUserSession' is a helper function
// that retrieves the current user's session from cookies/headers.
async function getUserSession() {
  // In a real app, this would securely fetch session details.
  // For demo, let's simulate a check.
  const hasSessionCookie = true; // Check request headers for auth cookie
  return hasSessionCookie ? { id: 'user123', name: 'Alice' } : null;
}

export default async function ProtectedDashboard() {
  const user = await getUserSession();

  if (!user) {
    redirect('/login'); // Use next/navigation's redirect for Server Components
  }

  return (
    <div>
      <h1>Welcome, {user.name}!</h1>
      <p>This is your confidential dashboard content.</p>
    </div>
  );
}

Protecting Data with Server Actions

Server Actions are powerful for handling form submissions and data mutations. It's critical to include authorization checks within them.

Before performing any database operations or sensitive logic, verify that the user initiating the action has the necessary permissions.

import { revalidatePath } from 'next/cache';

// Assume 'getCurrentUser' gets the user initiating the action
// and 'isAdmin' checks their role.
async function getCurrentUser() {
  // Simulate fetching user from session/context
  return { id: 'user123', role: 'admin' }; // Or 'guest'
}

async function createProduct(formData: FormData) {
  'use server';

  const user = await getCurrentUser();
  if (!user || user.role !== 'admin') {
    throw new Error('Unauthorized: Only admins can create products.');
  }

  const productName = formData.get('name') as string;
  // Simulate database operation
  console.log(`Admin ${user.id} created product: ${productName}`);
  // await db.products.create({ data: { name: productName } });

  revalidatePath('/admin/products');
  return { success: true, message: 'Product created!' };
}

export default function ProductForm() {
  return (
    <form action={createProduct}>
      <input type="text" name="name" placeholder="Product Name" required />
      <button type="submit">Create Product</button>
    </form>
  );
}

Handling Access Denied

When a user is unauthorized, you need to provide clear feedback. This can be:

Redirecting: To a login page or an 'Access Denied' page.
Displaying an error: Showing a message directly on the page.
Throwing an error: Allowing Next.js error.js boundaries to catch it.

Choose the method that best fits the user experience and the severity of the access attempt.

Defense in Depth

The best security approach is 'defense in depth'. This means applying multiple layers of security checks.

Client-side: Hide UI elements (not for security, but UX).
Middleware: Protect entire routes.
Server Components/Actions: Protect specific data operations.
Database: Use database-level permissions where appropriate.

Never trust client-side checks alone; always validate on the server.

Best Practices Summary

To ensure robust security for your Next.js application:

Always Authenticate & Authorize: Verify user identity and permissions for every sensitive operation.
Use Environment Variables: Store secrets (e.g., database credentials) securely.
Sanitize Inputs: Prevent injection attacks by validating and sanitizing all user input.
Least Privilege: Grant users only the minimum permissions they need.

Quick Check: Route Protection

You want to prevent unauthenticated users from accessing any page under /admin. Where should the primary check for this be implemented?

Recap: Protecting Your App

You've learned how to secure your Next.js 15 application using a multi-layered approach:

Middleware: Guards entire routes, redirecting unauthorized users.
Server Components: Conditionally render UI or redirect based on user authorization.
Server Actions: Protect data mutations by verifying user permissions before execution.

Combining these techniques provides robust protection for both your routes and the sensitive data within your application.

Sıkça Sorulan Sorular

“Yolları ve Verileri Koruma” dersi ücretsiz mi?

Evet — “Yolları ve Verileri Koruma” dersin tüm metni burada web'de ücretsiz olarak okunabilir. Etkileşimli olarak pratik yapmak (yerleşik kod editörü ve 7/24 yapay zeka koçu) ve Next.js 15 Fullstack (App Router + Server Actions) kursunun geri kalanını açmak için CoddyKit PRO'ya yükselt. Next.js 15 Fullstack (App Router + Server Actions) kursu toplamda 6 dersten oluşur.

“Yolları ve Verileri Koruma” dersinde ne öğreneceğim?

Kullanıcının kimlik doğrulama durumuna göre belirli yolları ve verileri korumak için ara katman yazılımı ve sunucu tarafı denetimleri uygulayın. Next.js 15 Fullstack (App Router + Server Actions) ile uygulamalı kodu tarayıcıda doğrudan çalıştırarak pratik yaparsın ve 7/24 yapay zeka koçu dersi çalışırken sorularını yanıtlar.

Next.js 15 Fullstack (App Router + Server Actions) öğrenmeye başlamak için deneyim gerekli mi?

Önceden deneyim gerekmez. CoddyKit'te Next.js 15 Fullstack (App Router + Server Actions), başlangıçtan ileri seviyeye kadar yapılandırıldığı için buradan başlayabilir veya başından başlayıp kendi hızında ilerleme yapabilirsin. Bu, 6 dersinin 3. dersidir.

“Yolları ve Verileri Koruma” dersi ne kadar sürer?

Çoğu CoddyKit dersi yaklaşık 5–10 dakika sürer. Her biri kısa ve etkileşimli olduğu için sabit ilerleme yaparsın ve web ile uygulama arasında tam olarak bıraktığın yerden devam edebilirsin.

Bu Next.js 15 Fullstack (App Router + Server Actions) dersinde kod yazıp çalıştırabilir miyim?

Evet. Her Next.js 15 Fullstack (App Router + Server Actions) dersi yerleşik bir kod editörü içerir, bu sayede tarayıcıda gerçek kod yazıp çalıştırabilir ve anlık yapay zeka geri bildirimi alırsın — yerel kurulum gerekli değildir.

Bu kursun tüm dersleri

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