PHP MVC Architecture Explained with a Minimal Example

MVC separates request coordination, domain state and rendered output.

What It Does and When to Use It

Separate business logic, input handling and rendering at a clearly identified boundary. Controllers translate HTTP input to operations; domain services implement rules; templates render escaped output.

Requirements, Inputs and Expected Behavior

Confirm the runtime, extension, environment variables, and permissions before running the examples in production. Keep database queries out of templates and avoid storing HTTP details in domain objects.

Example 1: Basic Operation

Separate business logic, input handling and rendering at a clearly identified boundary.

<?php
final class PostModel { public function title(int $id): string { return 'Post '.$id; } }
final class PostController { public function __construct(private PostModel $model) {} public function show(int $id): string { return '<h1>'.htmlspecialchars($this->model->title($id),ENT_QUOTES,'UTF-8').'</h1>'; } }
echo (new PostController(new PostModel()))->show(7);

Example 2: Behavior and Validation

Use the front controller to select responses while keeping routing separate from models.

<?php
$path=parse_url($_SERVER['REQUEST_URI']??'/',PHP_URL_PATH);
if ($path==='/health') { header('Content-Type: application/json'); echo json_encode(['status'=>'ok']); }
else { http_response_code(404); echo 'Not found'; }

Practical Example: Application Use

Render a trusted template path with controlled data; never derive template paths from user input.

<?php
function render(string $template, array $data): string {
    extract($data, EXTR_SKIP); ob_start();
    try { require $template; return (string)ob_get_clean(); }
    catch(Throwable $e) { ob_end_clean(); throw $e; }
}

Important Behavior and Edge Cases

The second example highlights: Use the front controller to select responses while keeping routing separate from models. The practical example adds: Render a trusted template path with controlled data; never derive template paths from user input.

Comparison with Related Approaches

Common Beginner Mistakes

Key Takeaways

• MVC separates request coordination, domain state and rendered output.
• Render a trusted template path with controlled data; never derive template paths from user input.
• Treat template names, route parameters and user data as separate trust domains.