what would cause the updated_at attribute time stamp to change?

Question

I'm wondering if anyone could share some information regarding the "updated_at" field in Mangento. What would cause this to change? Is it any update to the product, including category changes?

Answer 1

In the case of product entity, the attribute updated_at is an EAV attribute assigned which was created with a backend model.

class Mage_Catalog_Model_Resource_Setup extends Mage_Eav_Model_Entity_Setup
{

public function getDefaultEntities()
{
    return array(
        ....
        'updated_at'         => array(
            'type'                       => 'static',
            'input'                      => 'text',
            'backend'                    => 'eav/entity_attribute_backend_time_updated',
            'sort_order'                 => 20,
            'visible'                    => false,
        );
}
}

Each time the product entity is saved, the backend class Mage_Eav_Model_Entity_Attribute_Backend_Time_Updated is invoked by the method Mage_Eav_Model_Entity_Abstract::walkAttributes then execute the update of the date and time.

For other entities, like the Order entity, the updated_at is done in a different way while saving the model, updated_at is not an EAV attribute. So it does a simple $object->setUpdatedAt(Varien_Date::now()). See Mage_Sales_Model_Resource_Abstract::_prepareDataForSave()

Answer 2

Every time a products data is updated the updated_at field is updated as well. This includes when you change the categories that the product is assigned to in the products categories tab.