Using Multi-layer MVC Architecture in PHP

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To maintain code structure and improve sustainability in web applications, the MVC (Model-View-Controller) architecture is commonly used. MVC separates an application into three layers: Model (Data Management), View (Interface), and Controller (Business Logic), making the code more readable and maintainable.

Let’s create a simple MVC structure using PHP and understand how it works with a basic example. We'll build the core layers of a web application: Router, Controller, Model, and View. In real-world projects, MVC structures can become more complex, but the core principle is the separation of Model, View, and Controller.

1. Advantages of Using MVC

✅ Organized Code: Separates logic, data, and UI for a cleaner structure.
✅ Reusability: Components can be reused across multiple pages.
✅ Scalability: Easier to add new features by separating concerns.
✅ Maintainability: Update one part without breaking others.
✅ Testability: Each component can be tested independently.

2. MVC Folder Structure

Create the following directory structure to follow MVC principles:

GENEL

/mvc_project
  |-- app
  |   |-- controllers
  |   |   |-- HomeController.php
  |   |-- models
  |   |   |-- User.php
  |   |-- views
  |   |   |-- home.php
  |-- public
  |   |-- index.php
  |-- core
  |   |-- Router.php
  |-- config
  |   |-- config.php
  |-- .htaccess

Use a .htaccess file to route all requests to public/index.php:

APACHE

RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.+)$ public/index.php?url=$1 [QSA,L]

3. Coding the MVC Structure

3.1. Entry Point (public/index.php)

PHP

require_once '../core/Router.php';
$router = new Router();
$router->run();

3.2. Router Class (core/Router.php)

PHP

<?php
class Router {
    public function run() {
        $url = isset($_GET['url']) ? rtrim($_GET['url'], '/') : 'home';
        $controllerName = ucfirst($url) . 'Controller';
        $controllerFile = '../app/controllers/' . $controllerName . '.php';

        if (file_exists($controllerFile)) {
            require_once $controllerFile;
            $controller = new $controllerName();
            $controller->index();
        } else {
            http_response_code(404);
            echo '404 - Page Not Found';
        }
    }
}

3.3. Controller (app/controllers/HomeController.php)

PHP

<?php
class HomeController {
    public function index() {
        require_once '../app/models/User.php';
        $user = new User();
        $data = $user->getUsers();
        require_once '../app/views/home.php';
    }
}

3.4. Model (app/models/User.php)

PHP

<?php
class User {
    private $db;
    public function __construct() {
        $this->db = new PDO('mysql:host=localhost;dbname=mvc_project', 'root', '');
    }

    public function getUsers() {
        $stmt = $this->db->query('SELECT id, name FROM users');
        return $stmt->fetchAll(PDO::FETCH_ASSOC);
    }
}

3.5. View (app/views/home.php)

PHP

<!DOCTYPE html>
<html>
<head>
    <title>Home</title>
</head>
<body>
    <h1>Users</h1>
    <ul>
        <?php foreach ($data as $user) { ?>
            <li><?php echo htmlspecialchars($user['name']); ?></li>
        <?php } ?>
    </ul>
</body>
</html>

4. Running the MVC Project

Visit the following URL in your browser to test:

GENEL

http://localhost/mvc_project/public/home

If everything works, you should see a list of Users.

5. Security & Development Tips

🔹 Database Connection: Use PDO for secure and dynamic DB access.
🔹 Use an ORM: Implement Eloquent or Doctrine to enhance model power.
🔹 CSRF Protection: Secure forms with CSRF tokens.
🔹 Advanced Routing: Add RESTful and flexible routing mechanisms.
🔹 Input Sanitization: Clean user input with htmlspecialchars() and filter_input().
🔹 Error Handling: Use try-catch blocks and custom error pages.