/**
* Add filter
*
* @param object $column
* @return Mage_Adminhtml_Block_Catalog_Product_Edit_Tab_Related
*/
protected function _addColumnFilterToCollection($column)
{
// Set custom filter for in product flag
if ($column->getId() == 'in_products') {
$productIds = $this->_getSelectedProducts();
if (empty($productIds)) {
$productIds = 0;
}
if ($column->getFilter()->getValue()) {
$this->getCollection()->addFieldToFilter('entity_id', array('in' => $productIds));
} else {
if ($productIds) {
$this->getCollection()->addFieldToFilter('entity_id', array('nin' => $productIds));
}
}
} else {
parent::_addColumnFilterToCollection($column);
}
return $this;
}
