Skip walking attributes on EAV table update in Magento

Question

I've added to the customer_entity table a new column called source that I want to maintain through an admin form. This means I'll be working with the customer model to update that value; however, I've learned that it doesn't work that way with EAV models. So I can't call $model->setData('source')->save() because that value is not stored on an attribute table.

You might ask, "why not store it as an attribute?" There are a couple of reasons. Most importantly, I'm joining table data via resource adapters for a report. I was looking to write a "universal select" query that reads from both _entity tables and those serving simpler models.

So here's my problem:

When making changes to an EAV model in Magento, the abstract method Mage_Eav_Model_Entity_Abstract::walkAttributes gets triggered through the _afterSave method. As I understand it, this will call any registered backend models for handling CRUD operations.

I don't want this to happen. In my case, I'm working with the Mage_Customer_Model_Entity_Customer resource model. I'm calling its write adapter to manually execute an UPDATE query to maintain that source value. But it seems to be triggering a call to save addresses attached to that customer. This appears to be triggered as a result of those registered backend models on the customer attributes:

Mycompany_Customer_Model_Entity_Customer {

  ...

  public function setSource($customerId,$source=null) {
    $data=array(
      'entity_id'  => $customerId,
      'source'     => $source
    );

    Mage::getSingleton('core/resource')->getConnection('core_write')
      ->query("UPDATE `{$this->getEntityTable()}` SET `source`=? WHERE `entity_id`=?",$data);
  }

  ...

}

Why does this trigger attribute walking? How can I prevent this?

Answer 1

Just figured it out. I can get the underlying [PDO] connection object from a resource connection like so:

Mage::getSingleton('core/resource')->getConnection('core_write')
  ->getConnection()
  ->exec('my bound query goes here');

So here the Varien_Db_Adapter_Pdo_Mysql instance exposes the PDO object for me to use, taking it out of Magento's control.