Abstract Resource Model classes

Question

Looking at some of the Resource Models in Magento 2, you will find the following class definitions

namespace Magento\Catalog\Model\ResourceModel;

abstract class AbstractResource extends \Magento\Eav\Model\Entity\AbstractEntity
{
   ...
}

namespace Magento\Customer\Model\ResourceModel;

class Customer extends \Magento\Eav\Model\Entity\VersionControl\AbstractEntity
{
    ...
}

class Group extends \Magento\Framework\Model\ResourceModel\Db\VersionControl\AbstractDb
{
    ...
}

class Visitor extends \Magento\Framework\Model\ResourceModel\Db\AbstractDb
{
    ...
}

As you can see, there are VersionControl abstract classes and regular ones.

\Magento\Eav\Model\Entity\AbstractEntity
\Magento\Eav\Model\Entity\VersionControl\AbstractEntity
\Magento\Framework\Model\ResourceModel\Db\AbstractDb
\Magento\Framework\Model\ResourceModel\Db\VersionControl\AbstractDb

What is the difference between the two? When you create your own entities, should your Resource Models extend from the VersionControl class or the regular one?

Answer 1

So just to clarify, in Magento 2:

• \Magento\Eav\Model\Entity\VersionControl\AbstractEntity extends \Magento\Eav\Model\Entity\AbstractEntity
• \Magento\Framework\Model\ResourceModel\Db\VersionControl\AbstractDb extends \Magento\Framework\Model\ResourceModel\Db\AbstractDb

The VersionControl classes have the following extra functionalities:

• After loading and after saving an entity, they register a snapshot of entity data \Magento\Framework\Model\ResourceModel\Db\VersionControl\Snapshot, for tracking changes. That snapshot is used with the extra isModified function to check if entity was modified in the save method.
• When saving an entity, a \Magento\Framework\Model\ResourceModel\Db\VersionControl\RelationComposite is used to process model's relations saves before and after saving the object.

According to the Magento U fundamental course, when creating your own entities, you should use the \Magento\Eav\Model\Entity\AbstractEntity and the \Magento\Framework\Model\ResourceModel\Db\AbstractDb. The VersionControl classes are never mentionned over the course.