在preFlush处理程序中持久保存新的关联实体（无限递归）

I've created a entity listener for a given entity Foo, which listens to the preFlush event. I want to create a new Bar entity whenever the Foo entity is updated or created. My problem is the preFlush event is triggered again by the computeChangeSets() resulting in an endless loop. Anyone have a solution or an alternative method to approach this use case?

class SomeListener
{
    /**
     * @ORM\preFlush
     */
    public function onPreFlush(Foo $foo, PreFlushEventArgs $eventArgs)
    {
        $em = $eventArgs->getEntityManager();
        $uow = $em->getUnitOfWork();

        $bar = new Bar();
        $bar->setX('test');
        $foo->addBar($bar);

        $em->persist($bar);

        $meta = $em->getClassMetadata(get_class($foo));
        $uow->recomputeSingleEntityChangeSet($meta, $foo);
        $uow->computeChangeSets(); //This line invokes preFlush listener again
    }
}

The PreFlush event is dispatched before the change-sets are computed.

In other words: Your calls to recomputeSingleEntityChangeSet() and computeChangeSets() are not needed here. Remove those and your listener should be working fine!

PS: computeChangeSets() will compute all change-sets, so you don't need to call recomputeSingleEntityChangeSet() along with it.