public function save()
    {
        if (!$this->isValidPostSave()) {
            return;
        }

        // Check if post id is valid
        if (!isset($_REQUEST['id']) || empty($_REQUEST['id'])) {
            return trigger_error('Invalid post id. Please contact system administrator.');
        }

        $this->savePost();

        // If this is an ajax post, return "success" as plain text
        if (defined('DOING_AJAX') && DOING_AJAX) {
            echo "success";
            wp_die();
        }

        $this->notice(__('Modules saved', 'modularity'), ['updated']);
    }