Getting Started with Mezzio: A Modern Middleware Framework for PHP

Mezzio is an open-source microframework developed by the Laminas Project. It provides a middleware-based architecture that is perfect for building scalable and maintainable web applications in PHP. If you’re looking for a modern alternative to traditional MVC frameworks, Mezzio offers flexibility, performance, and the backing of a strong PHP community.

What is Mezzio?

Mezzio is built around the concept of middleware, giving developers the ability to compose applications from reusable components. It’s PSR-7 and PSR-15 compliant, which means it works seamlessly with modern PHP standards for HTTP message interfaces and middleware.

• Middleware architecture for clean and modular code
• Support for multiple routing, templating, and dependency injection containers
• PSR-compliant, interoperable with a wide range of PHP libraries
• Ideal for REST APIs and microservices

Installing Mezzio

To get started, you’ll need PHP 8.1 or higher, Composer, and a web server such as Apache or Nginx.

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composer create-project mezzio/mezzio-skeleton my-app
cd my-app
composer serve
  

The installer will prompt you to select your preferred container, router, and template engine. Once complete, your application will be accessible at http://localhost:8080.

Building a Simple Database Application with Mezzio and PDO

In this section, we’ll build a basic Mezzio middleware that connects to an existing MySQL database using PDO and returns data from a table in JSON format.

Step 1: Configure the Database Connection

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return [
    'db' => [
        'dsn'      => 'mysql:host=localhost;dbname=my_database;charset=utf8mb4',
        'username' => 'my_user',
        'password' => 'my_password',
    ],
];
  

Step 2: Create a PDO Service Factory

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namespace App\Factory;

use Psr\Container\ContainerInterface;
use PDO;

class PdoFactory
{
    public function __invoke(ContainerInterface $container): PDO
    {
        $config = $container->get('config')['db'];

        return new PDO(
            $config['dsn'],
            $config['username'],
            $config['password'],
            [
                PDO::ATTR_ERRMODE            => PDO::ERRMODE_EXCEPTION,
                PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
            ]
        );
    }
}
  

Step 3: Register the PDO Service

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return [
    'dependencies' => [
        'factories' => [
            PDO::class => \App\Factory\PdoFactory::class,
        ],
    ],
];
  

Step 4: Create Middleware to Fetch Data

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namespace App\Handler;

use PDO;
use Psr\Http\Server\RequestHandlerInterface;
use Psr\Http\Message\ServerRequestInterface;
use Psr\Http\Message\ResponseInterface;
use Laminas\Diactoros\Response\JsonResponse;

class UserListHandler implements RequestHandlerInterface
{
    private PDO $pdo;

    public function __construct(PDO $pdo)
    {
        $this->pdo = $pdo;
    }

    public function handle(ServerRequestInterface $request): ResponseInterface
    {
        $stmt = $this->pdo->query('SELECT id, name, email FROM users');
        $users = $stmt->fetchAll();

        return new JsonResponse($users);
    }
}
  

Step 5: Register the Route

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use App\Handler\UserListHandler;

$app->get('/users', UserListHandler::class, 'users.list');
  

Visit /users to see the user list output as JSON.

Screenshots

Watch the Live Screencast

Go Deeper with the Learning PHP Course

Want to master PHP from the ground up? Enroll in my course “Learning PHP”, designed for beginners and intermediate developers. It covers everything from syntax to building full applications, including Mezzio projects like the one above.

The book version of Learning PHP is also available and includes code walkthroughs, diagrams, and exercises to reinforce your understanding.

Enroll in the course or buy the book.

Book a One-on-One PHP or Mezzio Tutorial

If you’d prefer a more personalized approach, I offer one-on-one coaching sessions. Whether you’re just getting started or working on a Mezzio project, I can help you gain clarity and confidence.

Contact me to schedule your session.

Conclusion

Mezzio provides a modern and efficient framework for PHP developers who want more control and flexibility in building web applications. From middleware composition to dependency injection and database integration with PDO, it’s a framework that grows with your needs.

Explore the screencast, try the code examples, and check out the Learning PHP course to deepen your skills.