public function sortUrl()
    {
        $url = Request::url();
        $params = Input::get();

        $params['order_by'] = $this->index();
        if ($this->sortActive()) {
            $params['order_dir'] = mb_strtolower($this->_sortDirection()) == 'desc' ? 'ASC' : 'DESC';
        } else {
            $params['order_dir'] = ResourceTable::DEFAULT_SORT_DIR;
        }

        return $url.'?'.http_build_query($params);
    }