Access other entities while creating a Doctrine entity - entity-framework

Question

Say I have tables A, B in MySQL and Doctrine entity classes with the same names. Those entities are managed by Doctrine and are basically created according to Symfony/Doctrine docs.
Now I want to create entity C with columns: x, y. Whenever this entity is created or updated, I want to set the column values:
x: select count(*) from A where (some condition)
y: select sum(y) from B where (other condition)
pull some other data from A or B and store it as column value for C.
I want to do this in PHP and not use mysql triggers. I can't achieve from inside the Entity classes, because they don't have access to entity manager. I don't want to do this in the controller, as I want insert/update operations to be standardized, and I will need to do it from multiple controllers, and I generally don't think the controller is a good place for logic like this.
So I need some kind of class which manages entity C.
My question is: How do I call this manager class and where do I place it in Symfony? I am pretty sure this is a common need in Symfony (to access multiple entities while creating another entity), but I don't know how it is called and if there is a standard practice with them.

Answer 1

you can define service in app/config/services.yml and pass Entity manager as argument
services:
app.service.some_service:
class: AppBundle\Service\SomeService
arguments: ["#doctrine.orm.default_entity_manager"]
place your logic inside service
use Doctrine\ORM\EntityManagerInterface;
use AppBundle\Entity\SomeEntity;
class SomeService
{
/**
* #var EntityManagerInterface
*/
protected $entityManager;
public function __construct(EntityManagerInterface $entityManager) {
$this->entityManager = $entityManager;
}
public function getSomeEntity($id) {
$entity = $this->entityManager->getRepository(SomeEntity::class);
// do some work, return result..
}
}
call it from controller
$someService = $this->get('app.service.some_service');
$someService->getSomeEntity($id);
:)

Answer 2

I think you should create a Doctrine Event Subscriber as described in the documentation
I'll try to explain the basics.
1) Declare the service
services:
c_entity_counter_subscriber:
class: AppBundle\EventListener\CounterSubscriber
tags:
- { name: doctrine.event_subscriber, connection: default }
2) In the Subscriber count A and B properties
namespace AppBundle\EventListener;
use Doctrine\Common\EventSubscriber;
use Doctrine\ORM\Event\LifecycleEventArgs;
use AppBundle\Entity\A;
use AppBundle\Entity\B;
use AppBundle\Entity\C;
class CounterSubscriber implements EventSubscriber
{
public function getSubscribedEvents()
{
return array(
'postPersist',
'postUpdate',
);
}
public function postUpdate(LifecycleEventArgs $args)
{
$this->count($args);
}
public function postPersist(LifecycleEventArgs $args)
{
$this->count($args);
}
public function count(LifecycleEventArgs $args)
{
$entity = $args->getEntity();
if (!$entity instanceof C) {
return;
}
$entityManager = $args->getEntityManager();
// ... count/sum entities from A/B classes using $entityManager and update $entity
}
}