Creating middleware in Laravel - Practice Exercises

Challenge - 5 Problems

❓ component_behavior

intermediate

What is the output of this Laravel middleware?

Consider this middleware that checks if a user is an admin before allowing access. What will happen if a non-admin user tries to access a protected route?

Laravel

<?php
namespace App\Http\Middleware;
use Closure;
use Illuminate\Http\Request;
class CheckAdmin
{
    public function handle(Request $request, Closure $next)
    {
        if (!$request->user() || !$request->user()->is_admin) {
            return redirect('/home');
        }
        return $next($request);
    }
}

A The middleware throws a server error.

B The user sees a 404 error page.

C The user is allowed to proceed regardless of admin status.

D The user is redirected to '/home' if not admin.

💡 Hint

Look at the condition inside the handle method and what happens when it fails.

The middleware checks if the user is logged in and has the 'is_admin' flag. If not, it redirects to '/home'. Otherwise, it allows the request to continue.

📝 Syntax

intermediate

Which middleware registration is correct in Laravel?

You want to register a middleware named 'CheckAge' to be used in routes. Which option correctly registers it in the HTTP kernel?

A 'checkAge' => \App\Http\Middleware\CheckAge(),

B 'check.age' => \App\Http\Middleware\CheckAge::class,

C 'check_age' => new \App\Http\Middleware\CheckAge,

D 'check-age' => 'App\Http\Middleware\CheckAge',

💡 Hint

Middleware classes are registered as class names, not instances or strings without ::class.

Middleware must be registered as a key pointing to the fully qualified class name with ::class. Option B follows this pattern.

🔧 Debug

advanced

Why does this middleware cause a 'Too many redirects' error?

This middleware redirects users to '/login' if they are not authenticated. However, users get stuck in a redirect loop. What is the cause?

Laravel

<?php
namespace App\Http\Middleware;
use Closure;
use Illuminate\Http\Request;
class RedirectIfNotAuthenticated
{
    public function handle(Request $request, Closure $next)
    {
        if (!$request->user()) {
            return redirect('/login');
        }
        return $next($request);
    }
}

A The middleware redirects '/login' requests back to '/login' causing a loop.

B The middleware does not check if the user is authenticated correctly.

C The middleware should use abort(401) instead of redirect.

D The middleware is missing a return statement after redirect.

💡 Hint

Think about what happens when the user is already on the '/login' page.

The middleware redirects any unauthenticated user to '/login', including requests already targeting '/login'. This causes an infinite redirect loop.

❓ state_output

advanced

What is the value of $request->header('X-Custom') after this middleware runs?

This middleware adds a custom header to the request before passing it on. What will be the value of the 'X-Custom' header in the next middleware or controller?

Laravel

<?php
namespace App\Http\Middleware;
use Closure;
use Illuminate\Http\Request;
class AddCustomHeader
{
    public function handle(Request $request, Closure $next)
    {
        $request->headers->set('X-Custom', '12345');
        return $next($request);
    }
}

A Throws an error because headers are immutable

B null

C '12345'

D 'x-custom'

💡 Hint

Headers can be modified on the request object before passing it on.

The middleware sets the 'X-Custom' header to '12345'. This header will be available in the next middleware or controller.

🧠 Conceptual

expert

Which statement about Laravel middleware is true?

Choose the correct statement about how Laravel middleware works.

A Middleware can modify the request before passing it to the controller and the response before sending it back.

B Middleware only runs after the controller has processed the request.

C Middleware cannot stop a request from reaching the controller once started.

D Middleware must always return a JSON response.

💡 Hint

Think about the middleware handle method and the $next callback.

Middleware wraps the request handling process, allowing modification of both request and response. It can stop requests or modify responses.