Validate Category Attribute

Question

I have extended Mage_Catalog_Model_Category_Attribute_Source_Mode (and it's Resource model) to add two new modes display_mode values for Categories. Now I want to validate the value of that attribute when saving a category. Specifically, I want to make sure that is_anchor is always set to "No" when either of my two new modes are selected.

The problem is that neither Mage_Eav_Model_Entity_Attribute_Backend_Abstract::beforeSave nor Mage_Eav_Model_Entity_Attribute_Backend_Abstract::validate dispatch any events that I can listen for.

Mage_Catalog_Model_Category also has no _beforeSave method.

How can I validate category attributes on save? Thanks!

Answer 1

Actually Mage_Catalog_Model_Category does possess the event _beforeSave(). In order to see that, you need to look on that class with wide eyes :)

Mage_Catalog_Model_Category directly does not define _beforeSave. However you can see that, this class inherits from another class Mage_Catalog_Model_Abstract and it does possess _beforeSave. It looks like this

 protected function _beforeSave()
{
    $this->unlockAttributes();
    return parent::_beforeSave();
}

You can see that, this class again call its parent class. That parent class is nothing but Mage_Core_Model_Abstract. There you can see that _beforeSave defined like this.

protected function _beforeSave()
{
    if (!$this->getId()) {
        $this->isObjectNew(true);
    }
    Mage::dispatchEvent('model_save_before', array('object'=>$this));
    Mage::dispatchEvent($this->_eventPrefix.'_save_before', $this->_getEventData());
    return $this;
}

This function dispatches two events. Second one is important here. You can see that, it uses an event prefix in that event. Now take a look on Mage_Catalog_Model_Category. You can see that, it actually defines an event prefix there.

protected $_eventPrefix     = 'catalog_category';

This means, whenever category section is trying to save, _beforeSave method generates a unique event with name catalog_category_save_before. I think , you can use that event to save any category attribute

Hope that helps