Trying to persist another entity in preUpdate - symfony

Question

I'm trying to persist another entity in my preUpdate event listener, but it's not working...
Here is my code:
public function preUpdate(LifecycleEventArgs $args) {
$entity = $args->getEntity();
$em = $args->getEntityManager();
$uow = $em->getUnitOfWork();
$session = new Session();
$newLog = new Log();
$newLog->setDate(new DateTime());
if(!empty($this->toBePersisted))
{
array_push($toBePersisted, $historique);
}
else
{
$toBePersisted[0] = $historique;
}
}
public function postFlush(PostFlushEventArgs $event)
{
if(!empty($this->toBePersisted)) {
$em = $event->getEntityManager();
foreach ($this->toBePersisted as $element) {
$em->persist($element);
}
$this->toBePersisted = [];
$em->flush();
}
}
But my new log is not persisted...
Do you have any solution ?
Regards

Answer 1

You are using the wrong listeners to implement what you want to do. Quoting from Doctrine documentation for postFlush event:
postFlush is called at the end of EntityManager#flush(). EntityManager#flush() can NOT be called safely inside its listeners.
The right way to implement what you want is inside the onFlush event which is the more powerful doctrine event but is NOT a lifecycle callback. So you have to proper set up your listener in your services.yaml:
App\EventListener\LogListener:
tags:
- { name: doctrine.event_listener, event: onFlush }
and then in onFlush event:
class LogListener {
public function onFlush(OnFlushEventArgs $args) {
$em = $args->getEntityManager();
$uow = $em->getUnitOfWork();
foreach ($uow->getScheduledEntityUpdates() as $entity) {
if (!$entity instanceof YourUpdatedEntity) {
return;
}
$newLog = new Log();
$newLog->setDate(new DateTime());
$em->persist($newLog);
$classMetadata = $em->getClassMetadata(Log::class);
$uow->computeChangeSet($classMetadata, $newLog);
}
}
}
The computeChangeSet function call is needed because as stated in the documentation for onFlush event:
If you create and persist a new entity in onFlush, then calling EntityManager#persist() is not enough. You have to execute an additional call to $unitOfWork->computeChangeSet($classMetadata, $entity).