private function _validSort(array $params)
{
if (!isset($params['order_by']) || !isset($params['order_dir'])) {
return false;
}
if (!in_array(strtoupper($params['order_dir']), ['ASC', 'DESC'])) {
return false;
}
foreach ($this->_columns as $data) {
$column = new Column($data);
if ($column->index() == $params['order_by']) {
return true;
}
}
return false;
}