Mastering Request Flow Control with Laravel Middleware

Laravel's middleware provides a powerful mechanism for filtering HTTP requests entering your application. Let's explore how to leverage middleware effectively in your Laravel projects.

Creating Middleware

Create a new middleware using the Artisan command:

php artisan make:middleware EnsureTokenIsValid

This generates a new middleware class:

namespace App\Http\Middleware;

use Closure;

class EnsureTokenIsValid
{
    public function handle($request, Closure $next)
    {
        if ($request->input('token') !== 'my-secret-token') {
            return response('Invalid Token', 403);
        }
    
        return $next($request);
    }
}

Registering and Applying Middleware

Register route-specific middleware in app/Http/Kernel.php:

protected $routeMiddleware = [
    // ...
    'token' => \App\Http\Middleware\EnsureTokenIsValid::class,
];

Apply middleware to routes:

Route::get('profile', function () {
    //
})->middleware('token');

Middleware Parameters

Pass parameters to your middleware:

Route::put('post/{id}', function ($id) {
    //
})->middleware('role:editor');

In your middleware:

public function handle($request, Closure $next, $role)
{
    if (! $request->user()->hasRole($role)) {
        return response('Unauthorized', 401);
    }

    return $next($request);
}

Before & After Middleware

Perform actions before or after the request is handled:

public function handle($request, Closure $next)
{
    // Before the request is handled
    
    $response = $next($request);
    
    // After the request is handled
    
    return $response;
}

Real-World Example: CORS Middleware

public function handle($request, Closure $next)
{
    return $next($request)
        ->header('Access-Control-Allow-Origin', '*')
        ->header('Access-Control-Allow-Methods', 'GET, POST, PUT, DELETE, OPTIONS');
}

Laravel's middleware offers a clean, organized approach to filtering HTTP requests and responses. By leveraging middleware, you can create more secure and feature-rich applications while keeping your code modular and reusable.

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