RESTful API Server

Example Code

<?php
// Set the content type header to JSON for all responses
header('Content-Type: application/json');

// Simulate a database (in a real application, this would interact with a persistent store like a SQL or NoSQL database)
// For this example, data is reset with each request, demonstrating API logic for individual operations.
$products = [
    1 => ['id' => 1, 'name' => 'Laptop', 'price' => 1200],
    2 => ['id' => 2, 'name' => 'Mouse', 'price' => 25],
    3 => ['id' => 3, 'name' => 'Keyboard', 'price' => 75]
];
// In a real database, IDs would typically be auto-incremented.
// Here, we manually track a 'next ID' for new product creation based on existing keys.
$nextId = count($products) > 0 ? max(array_keys($products)) + 1 : 1;

// --- Request Parsing ---
$method = $_SERVER['REQUEST_METHOD']; // Get the HTTP method (GET, POST, PUT, DELETE)
$path = parse_url($_SERVER['REQUEST_URI'], PHP_URL_PATH); // Get the path part of the URL

// A simplified way to extract the resource and ID from the URL path.
// In a production environment, a dedicated routing library (e.g., FastRoute, or a full framework like Laravel/Symfony)
// with .htaccess rewrites would handle this more robustly, mapping clean URLs to actions.

// Example paths this script might handle (assuming your web server is configured to route all requests to this script):
// GET /products            -> get all products
// GET /products/1          -> get product with ID 1
// POST /products           -> create a new product
// PUT /products/1          -> update product with ID 1
// DELETE /products/1       -> delete product with ID 1

// Remove the script name from the path if present (e.g., '/api.php/products' -> '/products')
$scriptName = basename($_SERVER['SCRIPT_FILENAME']);
$scriptNamePos = strpos($path, $scriptName);

if ($scriptNamePos !== false) {
    $path = substr($path, $scriptNamePos + strlen($scriptName));
}

// Split the path into segments (e.g., ['', 'products', '1'] from '/products/1')
$pathSegments = explode('/', trim($path, '/'));

$resource = $pathSegments[0] ?? null; // The main resource, e.g., 'products'
$id = $pathSegments[1] ?? null;       // The ID of a specific resource, e.g., '1'

// Convert ID to integer if it exists for numerical indexing
if ($id !== null) {
    $id = (int)$id;
}

// --- API Logic based on Resource and Method ---
if ($resource === 'products') {
    switch ($method) {
        case 'GET':
            if ($id) {
                // Get a single product by ID
                if (isset($products[$id])) {
                    echo json_encode($products[$id]);
                } else {
                    http_response_code(404); // 404 Not Found
                    echo json_encode(['message' => 'Product not found.']);
                }
            } else {
                // Get all products
                // array_values is used to re-index the array numerically for JSON output (ensures a JSON array, not object if keys are non-sequential).
                echo json_encode(array_values($products));
            }
            break;

        case 'POST':
            // Create a new product
            $data = json_decode(file_get_contents('php://input'), true); // Get JSON data from request body
            if (!empty($data) && isset($data['name']) && isset($data['price'])) {
                $newProduct = [
                    'id' => $nextId,
                    'name' => $data['name'],
                    'price' => $data['price']
                ];
                $products[$nextId] = $newProduct; // Add to our simulated database
                http_response_code(201); // 201 Created status code for successful creation
                echo json_encode($newProduct);
            } else {
                http_response_code(400); // 400 Bad Request if data is missing or invalid
                echo json_encode(['message' => 'Invalid data provided for new product.']);
            }
            break;

        case 'PUT':
            // Update an existing product by ID
            if ($id && isset($products[$id])) {
                $data = json_decode(file_get_contents('php://input'), true);
                if (!empty($data) && isset($data['name']) && isset($data['price'])) {
                    $products[$id]['name'] = $data['name'];
                    $products[$id]['price'] = $data['price'];
                    echo json_encode($products[$id]);
                } else {
                    http_response_code(400); // 400 Bad Request
                    echo json_encode(['message' => 'Invalid data provided for product update.']);
                }
            } else {
                http_response_code(404); // 404 Not Found if product doesn't exist
                echo json_encode(['message' => 'Product not found for update.']);
            }
            break;

        case 'DELETE':
            // Delete a product by ID
            if ($id && isset($products[$id])) {
                unset($products[$id]); // Remove from our simulated database
                http_response_code(204); // 204 No Content (successful deletion with no response body)
            } else {
                http_response_code(404); // 404 Not Found if product doesn't exist
                echo json_encode(['message' => 'Product not found for deletion.']);
            }
            break;

        default:
            // Handle unsupported HTTP methods for the 'products' resource
            http_response_code(405); // 405 Method Not Allowed
            echo json_encode(['message' => 'Method Not Allowed for this resource.']);
            break;
    }
} else {
    // Handle requests for unknown resources
    http_response_code(404); // 404 Not Found
    echo json_encode(['message' => 'Resource Not Found.']);
}

?>