Add extra fields using JMS Serializer bundle

Question

I've an entity I usually serialize using the JMS Serializer bundle. I have to add to the serialization some fields that doesn't reside in the entity itself but are gathered with some db queries.

My idea was to create a custom object, fill the fields with the entity fields and add the custom one. But this seems a bit tricky and expensive to do for every variation (I use lot of serialization groups) of the class.

Is there a better/standard way to do this? Using a factory? Pre/Post serialization events?

Maybe I can listen for the serialization and checking entity type and serialization groups add the custom fields? But instead of making a query for each entity it would be better to gather all the data of the related entities and then add it to them. Any help is appreciated

Answer 1

I've found the solution by myself,

to add a custom field after the serialization has been done we've to create a listener class like this:

<?php  namespace Acme\DemoBundle\Listener;  use JMS\DiExtraBundle\Annotation\Service; use JMS\DiExtraBundle\Annotation\Tag; use JMS\DiExtraBundle\Annotation\Inject; use JMS\DiExtraBundle\Annotation\InjectParams; use Symfony\Component\HttpKernel\Event\PostResponseEvent; use Acme\DemoBundle\Entity\Team; use JMS\Serializer\Handler\SubscribingHandlerInterface; use JMS\Serializer\EventDispatcher\EventSubscriberInterface; use JMS\Serializer\EventDispatcher\PreSerializeEvent; use JMS\Serializer\EventDispatcher\ObjectEvent; use JMS\Serializer\GraphNavigator; use JMS\Serializer\JsonSerializationVisitor;  /**  * Add data after serialization  *  * @Service("acme.listener.serializationlistener")  * @Tag("jms_serializer.event_subscriber")  */ class SerializationListener implements EventSubscriberInterface {      /**      * @inheritdoc      */     static public function getSubscribedEvents()     {         return array(             array('event' => 'serializer.post_serialize', 'class' => 'Acme\DemoBundle\Entity\Team', 'method' => 'onPostSerialize'),         );     }      public function onPostSerialize(ObjectEvent $event)     {         $event->getVisitor()->addData('someKey','someValue');     } } 

That way you can add data to the serialized element.

Instead, if you want to edit an object just before serialization use the pre_serialize event, be aware that you need to already have a variable (and the correct serialization groups) if you want to use pre_serialize for adding a value.