protected function _addColumnFilterToCollection($column)
{
if ($this->getCollection()) {
$field = $column->getFilterIndex() ? $column->getFilterIndex() : $column->getIndex();
if ($column->getFilterConditionCallback()) {
call_user_func($column->getFilterConditionCallback(), $this->getCollection(), $column);
} else {
$cond = $column->getFilter()->getCondition();
if ($field && isset($cond)) {
if (strpos($field, 'am_attribute_') !== FALSE) {
$attribute = str_replace('am_attribute_', '', $field);
$this->getCollection()->addAttributeToFilter($attribute, $cond);
} else {
if ($field == "low_stock") {
$this->getCollection()->addFilter("if(stock_item.item_id IS NULL, 0 , 1)", $cond);
} else {
parent::_addColumnFilterToCollection($column);
}
}
}
}
}
return $this;
}
