Advanced WordPress Architecture

Master advanced WordPress development patterns including REST API endpoints, WP-CLI commands, performance optimization, and caching strategies for scalable WordPress applications.

1. REST API Development

The WordPress REST API provides a powerful interface for creating custom endpoints with proper authentication, validation, and response formatting.

Endpoint Registration with Namespacing

add_action( 'rest_api_init', 'register_custom_rest_routes' );
function register_custom_rest_routes() {
    // Namespace: myplugin/v1 (enables versioning)
    $namespace = 'myplugin/v1';

    // GET /wp-json/myplugin/v1/books
    register_rest_route( $namespace, '/books', [
        'methods'  => 'GET',
        'callback' => 'get_books_callback',
        'permission_callback' => '__return_true', // Public endpoint
        'args' => [
            'per_page' => [
                'default' => 10,
                'validate_callback' => function( $param ) {
                    return is_numeric( $param ) && $param > 0 && $param <= 100;
                },
                'sanitize_callback' => 'absint',
            ],
            'page' => [
                'default' => 1,
                'validate_callback' => function( $param ) {
                    return is_numeric( $param ) && $param > 0;
                },
                'sanitize_callback' => 'absint',
            ],
        ],
    ]);

    // GET /wp-json/myplugin/v1/books/(?P<id>\d+)
    register_rest_route( $namespace, '/books/(?P<id>\d+)', [
        'methods'  => 'GET',
        'callback' => 'get_book_callback',
        'permission_callback' => '__return_true',
        'args' => [
            'id' => [
                'validate_callback' => function( $param ) {
                    return is_numeric( $param );
                },
                'sanitize_callback' => 'absint',
            ],
        ],
    ]);

    // POST /wp-json/myplugin/v1/books (authenticated)
    register_rest_route( $namespace, '/books', [
        'methods'  => 'POST',
        'callback' => 'create_book_callback',
        'permission_callback' => function() {
            return current_user_can( 'edit_posts' );
        },
        'args' => [
            'title' => [
                'required' => true,
                'type' => 'string',
                'validate_callback' => function( $param ) {
                    return is_string( $param ) && strlen( $param ) > 0;
                },
                'sanitize_callback' => 'sanitize_text_field',
            ],
            'content' => [
                'required' => false,
                'type' => 'string',
                'sanitize_callback' => 'wp_kses_post',
            ],
            'status' => [
                'default' => 'draft',
                'enum' => [ 'draft', 'publish', 'private' ],
            ],
        ],
    ]);

    // PUT /wp-json/myplugin/v1/books/(?P<id>\d+)
    register_rest_route( $namespace, '/books/(?P<id>\d+)', [
        'methods'  => 'PUT',
        'callback' => 'update_book_callback',
        'permission_callback' => function( $request ) {
            $book_id = $request->get_param( 'id' );
            return current_user_can( 'edit_post', $book_id );
        },
        'args' => [
            'id' => [
                'validate_callback' => function( $param ) {
                    return is_numeric( $param );
                },
                'sanitize_callback' => 'absint',
            ],
            'title' => [
                'type' => 'string',
                'sanitize_callback' => 'sanitize_text_field',
            ],
            'content' => [
                'type' => 'string',
                'sanitize_callback' => 'wp_kses_post',
            ],
        ],
    ]);

    // DELETE /wp-json/myplugin/v1/books/(?P<id>\d+)
    register_rest_route( $namespace, '/books/(?P<id>\d+)', [
        'methods'  => 'DELETE',
        'callback' => 'delete_book_callback',
        'permission_callback' => function( $request