Akeneo 2.2.8 : How can I get the original attribute data in the akeneo.storage.pre_save event? - symfony

Question

I'm using Akeneo 2.2.8 and I'm trying to use the akeneo.storage.pre_save-event to compare the original product data with the new data provided. I do this by subscribing to the akeneo.storage.pre_save-event:
In event_subscribers.yml:
parameters:
vendor.bundle.event_subscriber.product_save.class: Vendor\Bundle\CustomBundle\EventSubscriber\ProductSaveSubscriber
services:
vendor.bundle.event_subscriber.product_save:
class: '%vendor.bundle.event_subscriber.product_save.class%'
arguments:
- '#pim_catalog.repository.product'
tags:
- { name: kernel.event_listener, event: akeneo.storage.pre_save, method: onPreSave, priority: 255 }
In ProductSaveSubscriber.php:
/**
* #var ProductRepositoryInterface
*/
protected $productRepository;
public function __construct(ProductRepositoryInterface $productRepository)
{
$this->productRepository = $productRepository;
}
public function onPreSave(GenericEvent $event)
{
/** #var Product $subject */
$subject = $event->getSubject();
if ($subject instanceof Product) {
$originalProduct = $this->productRepository->findOneByIdentifier($subject->getIdentifier());
foreach ($subject->getAttributes() as $attribute) {
if ($attribute->getReadOnly()) {
echo "{$attribute->getCode()} : {$subject->getValue($attribute->getCode())}\n";
echo "{$attribute->getCode()} : {$originalProduct->getValue($attribute->getCode())}\n";
}
}
}
}
Now when I run this code, I expect the second echo-statement to give the original data (since I've loaded that anew). However, the original product I load from the repository also has the new data.
Another thing to note here is that if I add a die()-statement, the data is not stored in the database. So it seems that the repository returns the in-memory model or something like that.
Can anyone point me in the right direction? Or am I using the wrong approach to compare newly-entered data with already existing data?

Answer 1

Now when I run this code, I expect the second echo-statement to give
the original data (since I've loaded that anew). However, the original
product I load from the repository also has the new data.
This might be because the object is referenced in doctrine's unit of work. So when you use the repository to fetch what you think is the original object, might actually be the same object you've updated.
Another thing to note here is that if I add a die()-statement, the
data is not stored in the database. So it seems that the repository
returns the in-memory model or something like that.
That's because since your subscriber is listening on the PRE_SAVE event, the updated product has not been flushed in the database yet. Saving a product goes this way:
PRE_SAVE event thrown
COMMIT / FLUSH
POST_SAVE event thrown
So if you call die during the PRE_SAVE event, the COMMIT / FLUSH won't be called.
Can anyone point me in the right direction? Or am I using the wrong
approach to compare newly-entered data with already existing data?
I don't know your particular use case but you might want to use a Query function (see https://github.com/akeneo/pim-community-dev/blob/2.2/src/Pim/Bundle/CatalogBundle/Doctrine/ORM/Query/FindAttributesForFamily.php). It's purpose is to directly fetch in the database the data you need (it will be the original value since the product hasn't been flushed in DB on PRE_SAVE)
I hope this helps.