custom_normalizer.rst

.. index::
   single: Serializer; Custom normalizers

How to Create your Custom Normalizer

The :doc:`Serializer component </components/serializer>` uses normalizers to transform any data into an array. The component provides several :doc:`built-in normalizers </serializer/normalizers>` but you may need to create your own normalizer to transform an unsupported data structure.

Creating a New Normalizer

Imagine you want add, modify, or remove some properties during the serialization process. For that you'll have to create your own normalizer. But it's usually preferable to let Symfony normalize the object, then hook into the normalization to customize the normalized data. To do that, leverage the ObjectNormalizer:

namespace App\Serializer;

use App\Entity\Topic;
use Symfony\Component\Routing\Generator\UrlGeneratorInterface;
use Symfony\Component\Serializer\Normalizer\ContextAwareNormalizerInterface;
use Symfony\Component\Serializer\Normalizer\ObjectNormalizer;

class TopicNormalizer implements ContextAwareNormalizerInterface
{
    private $router;
    private $normalizer;

    public function __construct(UrlGeneratorInterface $router, ObjectNormalizer $normalizer)
    {
        $this->router = $router;
        $this->normalizer = $normalizer;
    }

    public function normalize($topic, $format = null, array $context = [])
    {
        $data = $this->normalizer->normalize($topic, $format, $context);

        // Here, add, edit, or delete some data:
        $data['href']['self'] = $this->router->generate('topic_show', [
            'id' => $topic->getId(),
        ], UrlGeneratorInterface::ABSOLUTE_URL);

        return $data;
    }

    public function supportsNormalization($data, $format = null, array $context = [])
    {
        return $data instanceof Topic;
    }
}

Registering it in your Application

Before using this normalizer in a Symfony application it must be registered as a service and :doc:`tagged </service_container/tags>` with serializer.normalizer. If you're using the :ref:`default services.yaml configuration <service-container-services-load-example>`, this is done automatically!