Events.md

Events

The entity manager fires pre and post events on most calls, each event is enumerated in the Event enum class.

Aborting Events

Both pre and post events can be aborted, however only aborting a pre event will actually cancel the operation. Aborting a post event will not undo the action, but it does give you an opportunity to change the return value of the operation.

To change the return value, you must also call $event->setAbort(true);.

Example

Manipulating an entity before persisting:

$entity_manager->getDispatcher()->addListener(Event::PRE_PERSIST, function(PersistEvent $event) {
    $entity = $event->getEntity();
    // Manipulate entity here
});

Manipulating the result of a retrieval:

$entity_manager->getDispatcher()->addListener(Event::POST_RETRIEVE, function(RetrieveEvent $event) {
    $entity = $event->getEntity();
    if ($entity instanceof CoolEntity) {
        $entity->setCoolFactor(10);
    } else {
        $event->setReturnValue(new CoolEntity());
        $event->setAbort(true);
    }
});

The above example will either modify the retrieved entity, or completely override the return result.

Hydration exceptions as Events

There is an option available to have NotFoundException exceptions that are thrown during hydration of related entities be converted to Event::HYDRATION_EXCEPTION events containing the exception that was thrown.

$entity_manager->getConfig()->setHydrationExceptionsAsEvents(true);
$entity_manager->getDispatcher()->addListener(Event::HYDRATION_EXCEPTION, function(HydrationExceptionEvent $event) {
    $exception = $event->getException();
});

This is useful only in cases where relationships still exist to non-existant entities and you would prefer to skip over these during hydration rather than have an excption thrown which is impossible to recover from from within userland code.

The only caveat to using this approach currently is that a count of results returned from a sortedQuery may not be the same as the number of iterations you can make over that result.