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);
}