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.. index::
   single: Serializer

How to Use the Serializer

Serializing and deserializing to and from objects and different formats (e.g. JSON or XML) is a very complex topic. Symfony comes with a :doc:`Serializer Component </components/serializer>`, which gives you some tools that you can leverage for your solution.

In fact, before you start, get familiar with the serializer, normalizers and encoders by reading the :doc:`Serializer Component </components/serializer>`.

Activating the Serializer

The serializer service is not available by default. To turn it on, activate it in your configuration:

.. configuration-block::

    .. code-block:: yaml

        # app/config/config.yml
        framework:
            # ...
            serializer:
                enabled: true

    .. code-block:: xml

        <!-- app/config/config.xml -->
        <framework:config>
            <!-- ... -->
            <framework:serializer enabled="true" />
        </framework:config>

    .. code-block:: php

        // app/config/config.php
        $container->loadFromExtension('framework', array(
            // ...
            'serializer' => array(
                'enabled' => true,
            ),
        ));

Using the Serializer Service

Once enabled, the serializer service can be injected in any service where you need it or it can be used in a controller like the following:

// src/AppBundle/Controller/DefaultController.php
namespace AppBundle\Controller;

use Symfony\Bundle\FrameworkBundle\Controller\Controller;

class DefaultController extends Controller
{
    public function indexAction()
    {
        $serializer = $this->get('serializer');

        // ...
    }
}

Adding Normalizers and Encoders

Once enabled, the serializer service will be available in the container and will be loaded with two :ref:`encoders <component-serializer-encoders>` (:class:`Symfony\\Component\\Serializer\\Encoder\\JsonEncoder` and :class:`Symfony\\Component\\Serializer\\Encoder\\XmlEncoder`) and the :ref:`ObjectNormalizer normalizer <component-serializer-normalizers>`.

You can load normalizers and/or encoders by tagging them as :ref:`serializer.normalizer <reference-dic-tags-serializer-normalizer>` and :ref:`serializer.encoder <reference-dic-tags-serializer-encoder>`. It's also possible to set the priority of the tag in order to decide the matching order.

Here is an example on how to load the :class:`Symfony\\Component\\Serializer\\Normalizer\\GetSetMethodNormalizer`:

.. configuration-block::

    .. code-block:: yaml

        # app/config/services.yml
        services:
            get_set_method_normalizer:
                class: Symfony\Component\Serializer\Normalizer\GetSetMethodNormalizer
                public: false
                tags:
                    - { name: serializer.normalizer }

    .. code-block:: xml

        <!-- app/config/services.xml -->
        <services>
            <service id="get_set_method_normalizer" class="Symfony\Component\Serializer\Normalizer\GetSetMethodNormalizer" public="false">
                <tag name="serializer.normalizer" />
            </service>
        </services>

    .. code-block:: php

        // app/config/services.php
        use Symfony\Component\DependencyInjection\Definition;

        $definition = new Definition(
            'Symfony\Component\Serializer\Normalizer\GetSetMethodNormalizer'
        ));
        $definition->setPublic(false);
        $definition->addTag('serializer.normalizer');
        $container->setDefinition('get_set_method_normalizer', $definition);

Using Serialization Groups Annotations

Enable :ref:`serialization groups annotation <component-serializer-attributes-groups>` with the following configuration:

.. configuration-block::

    .. code-block:: yaml

        # app/config/config.yml
        framework:
            # ...
            serializer:
                enable_annotations: true

    .. code-block:: xml

        <!-- app/config/config.xml -->
        <framework:config>
            <!-- ... -->
            <framework:serializer enable-annotations="true" />
        </framework:config>

    .. code-block:: php

        // app/config/config.php
        $container->loadFromExtension('framework', array(
            // ...
            'serializer' => array(
                'enable_annotations' => true,
            ),
        ));

Next, add the :ref:`@Groups annotations <component-serializer-attributes-groups-annotations>` to your class and choose which groups to use when serializing:

$serializer = $this->get('serializer');
$json = $serializer->serialize(
    $someObject,
    'json', array('groups' => array('group1'))
);

In addition to the @Groups annotation, the Serializer component also supports Yaml or XML files. These files are automatically loaded when being stored in one of the following locations:

The serialization.yml or serialization.xml file in the Resources/config/ directory of a bundle;
All *.yml and *.xml files in the Resources/config/serialization/ directory of a bundle.

Enabling the Metadata Cache

Metadata used by the Serializer component such as groups can be cached to enhance application performance. Any service implementing the Doctrine\Common\Cache\Cache interface can be used.

A service leveraging APCu (and APC for PHP < 5.5) is built-in.

.. configuration-block::

    .. code-block:: yaml

        # app/config/config_prod.yml
        framework:
            # ...
            serializer:
                cache: serializer.mapping.cache.apc

    .. code-block:: xml

        <!-- app/config/config_prod.xml -->
        <framework:config>
            <!-- ... -->
            <framework:serializer cache="serializer.mapping.cache.apc" />
        </framework:config>

    .. code-block:: php

        // app/config/config_prod.php
        $container->loadFromExtension('framework', array(
            // ...
            'serializer' => array(
                'cache' => 'serializer.mapping.cache.apc',
            ),
        ));

Going Further with the Serializer

ApiPlatform provides an API system supporting JSON-LD and Hydra Core Vocabulary hypermedia formats. It is built on top of the Symfony Framework and its Serializer component. It provides custom normalizers and a custom encoder, custom metadata and a caching system.

If you want to leverage the full power of the Symfony Serializer component, take a look at how this bundle works.

.. toctree::
    :maxdepth: 1
    :glob:

    serializer/*

Uh oh!