\d+)', array( 'methods' => 'GET', 'permission_callback' => 'check_permission', 'callback' => 'fetch_user_by_id', )); }); add_action('rest_api_init', function () { register_rest_route('wiaas/v1', '/user', array( 'methods' => 'GET', 'permission_callback' => 'check_permission', 'callback' => 'fetch_user_by_id', )); });