Advanced WordPress Development

Chapter 6: WordPress REST API

6.1 REST API Overview

WordPress REST API provides programmatic access to WordPress data.

API Endpoints:

• /wp-json/wp/v2/posts: Posts endpoint
• /wp-json/wp/v2/pages: Pages endpoint
• /wp-json/wp/v2/users: Users endpoint
• /wp-json/wp/v2/media: Media endpoint

6.2 Creating Custom Endpoints

Create custom REST API endpoints.

// Register custom endpoint
add_action('rest_api_init', 'register_custom_endpoint');

function register_custom_endpoint() {
    register_rest_route('myplugin/v1', '/data', array(
        'methods' => 'GET',
        'callback' => 'get_custom_data',
        'permission_callback' => '__return_true',
    ));
}

function get_custom_data($request) {
    return new WP_REST_Response(array('data' => 'value'), 200);
}

6.3 REST API Authentication

Secure REST API endpoints with authentication.

• Application Passwords: User-specific passwords
• OAuth: Third-party authentication
• JWT: JSON Web Tokens
• Cookie Authentication: For logged-in users

6.4 REST API Schema

Define schema for custom endpoints.

register_rest_route('myplugin/v1', '/data', array(
    'methods' => 'GET',
    'callback' => 'get_custom_data',
    'args' => array(
        'id' => array(
            'type' => 'integer',
            'required' => true,
            'validate_callback' => function($param) {
                return is_numeric($param);
            }
        ),
    ),
));

6.5 Headless WordPress

Use WordPress as a headless CMS with REST API.

• WordPress backend for content management
• Frontend built with React, Vue, or other frameworks
• REST API connects frontend and backend
• Better performance and flexibility