Creating a Front Controller in PHP

A front controller is one public entry script that dispatches HTTP requests to application code.

What It Does

A front controller is one public entry script that dispatches HTTP requests to application code. The following examples distinguish a normal use case, a boundary case and a practical application.

Requirements and Compatibility

PHP 8.x and a local test environment. Apply input validation, correct error handling and the requirements of any optional libraries.

The code focuses on the core concept. Production implementation may also need routes, validation, persistence, authorization or deployment tooling.

Example 1: Basic Behavior

Understand the primary operation and its inputs.

<?php
$routes = ['GET /items' => fn () => 'list', 'POST /items' => fn () => 'create'];
$key = 'GET /items';
echo isset($routes[$key]) ? $routes[$key]() : '404';

Example 2: Another Case

Check failure behavior or a different execution path.

<?php
$path = parse_url('/items/17?view=short', PHP_URL_PATH);
if (preg_match('~^/items/(?P<id>\d+)$~D', $path, $m)) echo (int) $m['id'];

Practical Example: Putting It to Use

Centralize routing and response construction in a single public entry point.

<?php
$method = 'GET'; $path = '/health';
$handlers = ['GET /health' => fn () => ['status' => 200, 'json' => ['ok' => true]]];
$response = isset($handlers["$method $path"]) ? $handlers["$method $path"]() : ['status' => 404];
print_r($response);

Important Behavior and Edge Cases

Keep configuration and source files outside the public document root.

Comparison with Related Functions or Approaches

Common Beginner Mistakes

Key Takeaways

• A front controller is one public entry script that dispatches HTTP requests to application code.
• Keep configuration and source files outside the public document root.
• Combine routing, authorization and response rendering through clear boundaries.

Before adapting these examples, verify the return values, test the failure paths and confirm that your application meets its security and environment requirements.