PHP REST APIs

What is a REST API?

A REST API (Representational State Transfer Application Programming Interface) allows different applications to communicate with each other using HTTP methods. In PHP, REST APIs are commonly used for mobile apps, frontend frameworks (React, Vue), and third-party integrations.

Key Principles of REST

• Client–Server architecture

• Stateless communication

• Uses standard HTTP methods

• Resource-based URLs

• JSON is the most common response format

Common HTTP Methods

REST API Response Format (JSON)

{
  "status": true,
  "message": "Data fetched successfully",
  "data": []
}

Basic PHP REST API Setup

Set Headers

header("Content-Type: application/json");
header("Access-Control-Allow-Origin: *");
header("Access-Control-Allow-Methods: GET, POST, PUT, DELETE");

Handling HTTP Request Method

$method = $_SERVER['REQUEST_METHOD'];

GET Request Example

if ($method === 'GET') {
    echo json_encode([
        "status" => true,
        "message" => "GET request successful"
    ]);
}

POST Request Example

if ($method === 'POST') {
    $data = json_decode(file_get_contents("php://input"), true);

    echo json_encode([
        "status" => true,
        "data" => $data
    ]);
}

CRUD Example with PHP REST API

Read (GET)

$stmt = $pdo->query("SELECT * FROM users");
$data = $stmt->fetchAll();

echo json_encode($data);

Create (POST)

$data = json_decode(file_get_contents("php://input"), true);

$stmt = $pdo->prepare("INSERT INTO users (name, email) VALUES (?, ?)");
$stmt->execute([$data['name'], $data['email']]);

Update (PUT)

$data = json_decode(file_get_contents("php://input"), true);

$stmt = $pdo->prepare("UPDATE users SET name=? WHERE id=?");
$stmt->execute([$data['name'], $data['id']]);

Delete (DELETE)

parse_str(file_get_contents("php://input"), $data);

$stmt = $pdo->prepare("DELETE FROM users WHERE id=?");
$stmt->execute([$data['id']]);

API Routing (Simple Example)

$endpoint = $_GET['endpoint'] ?? '';

if ($endpoint === 'users') {
    // handle users API
}

API Authentication (Basic Token Example)

$headers = getallheaders();

if ($headers['Authorization'] !== 'Bearer mytoken') {
    http_response_code(401);
    echo json_encode(["message" => "Unauthorized"]);
    exit;
}

HTTP Status Codes

Error Handling in REST APIs

http_response_code(400);
echo json_encode(["error" => "Invalid request"]);

Best Practices for PHP REST APIs

• Use meaningful endpoints (/api/users)

• Always return JSON

• Use proper HTTP status codes

• Validate input data

• Secure APIs using tokens/JWT

• Version your APIs (/api/v1/)

Common Use Cases

• Mobile app backend

• SPA frontend (React, Angular)

• Microservices

• Third-party integrations

Conclusion

PHP REST APIs provide a powerful way to build scalable, platform-independent services. Understanding REST principles and secure API development is essential for modern backend development.