pre-transform-event.md

Pre transform event

Since FOSElasticaBundle 3.2.0, we now dispatch an event before an object is transformed into an Elastica document. It allows you to do some necessary operation before indexing.

For example, you have a backoffice which is exclusively used in a certain locale. When you save objects which have translation, you have to index objects in several indices (one per locale supported). It is necessary to reload data before transforming to document with the good locale if it is not already done.

You can even manipulate empty Elastica document created in FOS\ElasticaBundle\Transformer\ModelToElasticaAutoTransformer and fields concerned by index process.

Set up an event listener or subscriber for FOS\ElasticaBundle\Event\PreTransformEvent to be able to do some operation on your objects.

namespace AcmeBundle\EventListener;

use Symfony\Component\EventDispatcher\EventSubscriberInterface;
use FOS\ElasticaBundle\Event\PreTransformEvent;

class PreTransformListener implements EventSubscriberInterface
{
    private $anotherService;
    
    // ...
    
    public function doPreTransform(PreTransformEvent $event)
    {
        $this->anotherService->reloadTranslation($event->getObject());
    }
    
    public static function getSubscribedEvents()
    {
        return [
            PreTransformEvent::class => 'doPreTransform',
        ];
    }
}

Service definition (when autoconfigure is disabled):

acme.listener.custom_property:
    class: AcmeBundle\EventListener\PreTransformListener
    tags:
        - { name: kernel.event_subscriber }