Part 7 - Advanced ORM - Entity Attribute Value
March 1, 2011 | in Magento Step by Step
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In the first ORM article we told you there were two kinds of Models in Magento. Regular, or "simple" Models, and Entity Attribute Value (or EAV) Models. We also told you this was a bit of a fib. Here's where we come clean.
ALL Magento Models inherit from the Mage_Core_Model_Abstract / Varien_Object chain. What makes something either a simple Model or an EAV Model is its Model Resource. While all resources extend the base Mage_Core_Model_Resource_Abstract class, simple Models have a resource that inherits from Mage_Core_Model_Mysql4_Abstract, and EAV Models have a resource that inherits from Mage_Eav_Model_Entity_Abstract
If you think about it, this makes sense. As the end-programmer-user of the system you want a set of methods you can use to talk to and manipulate your Models. You don't care what the back-end storage looks like, you just want to get properties and invoke methods that trigger business rules.