Symfony2 - Doctrine - 更新后没有变更集

Question

So i am sending an email when a certain value on an entity is changed. I only want the email to send after the update in case the update fails for what ever reason. so on the preUpdate I can do this

public function preUpdate(LifecycleEventArgs $args){

    if ($args->hasChangedField('value') && is_null($args->getOldValue('value'))) {
        $this->sendEmail();
    }

}

but i need to do this on postUpdate and as these methods are not available on postUpdate i refactored it to look like this:

public function postUpdate(LifecycleEventArgs $args){

    $entity      = $args->getEntity();
    $changeSet = $args->getEntityManager()->getUnitOfWork()->getEntityChangeSet($entity);

    if ($entity  instanceof Entity && isset( $changeSet['value'] ) && empty( $changeSet['value'][0] )) {
        $this->sendEmail();
    }
}

However this returns an empty change set, but changes have been made and can be seen in preUpdate. Can anyone see what i am doing wrong? help would be much appreciated :)

Answer 1

On preUpdate event you get event object of class PreUpdateEventArgs where You have change set for entity.

On postUpdate you just get event object of class LifecycleEventArgs where you can ask only for Updated entity (and get latest state of it).

If you want to play with changeset then you need to do it before actual updating entity (preUpdate event).