Save 2 objects with a reference to each other in one transaction

Question

for some security reasons I try to save 2 custom objects (different models) into the database, via:

try {
    $transaction = Mage::getResourceModel('core/transaction')
        ->addObject($object1)
        ->addObject($object2);
    $transaction->save();
} catch (Exception $e) {
    echo $e->getMessage();
}

The problem is, that the database table of $object2 contains a reference id to $object1, but this is auto incremented in $object1 and unknown at this point.

To visualize my problem:

database table of $object1:

 entity_id  |  ...  |  ...
 -----------------------------
 1234       |  ...  |  ...

the database table of $object2 should looks like this:

 entity_id  |  object_1_id  |  ...
 ---------------------------------
 5678       |  1234         |  ...

How can I get the auto incremented id of $object1 and save within the same transaction to $object2 table? Is it possible? Makes that sense?

Thanks for help.

Answer 1

It looks to me like you have a "one to many" relation here. $object1 can have associated 0, 1, 2...,n instances of $object 2.
So you can say that $object1 is a parent entity for $object2.
you can handle the save of both parent and child entities in the same transaction like this.

Let's say that the class (Model) for $object1 is called ParentObject and the class (model) for $object2 is ChildObject.

In ParentObject add this member:

protected $childObjects = array();

a method called addChildObject.

public function addChildObject(ChildObject $childObject)
{
    $this->childObjects[] = $childObject;
    return $this;
}

Magento has callbacks that are executed for each save method call from any model.
So you need to implement one of these methods called _afterSave in the ParentObject class. This one is called after saving the ParentObject instance, so you have an ID you can use.

protected function _afterSave()
{
    foreach ($this->childObjects as $childObject) 
    {
        //set the $object1Id (the FK value) for child objects and save them
        $childObject->setObject1Id($this->getId());
        $childObject->save();
    }
    return parent::_afterSave();
}

Now all you have to do in your code is:

$object1->addChildObject($object2);
$object1->save();

and everything will be saved in the same transaction.