I try to create custom grid with orders shipped by some shipping method (for example TNT). Here is a method where should be a filter:
protected function _prepareCollection()
{
$collection = Mage::getResourceModel($this->_getCollectionClass());
$this->setCollection($collection);
return parent::_prepareCollection();
}
I'm going to use something like addFieldToFilter(), but I don't know field name. Could you help me?