public function addAttributeToSort($attribute, $dir = 'asc')
{
parent::addAttributeToSort($attribute, $dir);
if ($attribute == 'position') {
$orders = $this->getSelect()->getPart('order');
$this->getSelect()->reset('order');
foreach ($orders as $order) {
$this->getSelect()->order(str_replace('cat_index_position', 'cat_index.position', $order[0]), $order[1]);
}
}
return $this;
}
