protected function saveSingleValue($value, int $post_id)
    {
        $previous = get_post_meta($post_id, $this->getName(), true);

        if (is_null($value) || empty($value)) {
            delete_post_meta($post_id, $this->getName());
        } elseif (empty($previous)) {
            add_post_meta($post_id, $this->getName(), $value, true);
        } else {
            update_post_meta($post_id, $this->getName(), $value, $previous);
        }
    }