.. 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>` documentation.

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: { enable_annotations: true }
            # Alternatively, if you don't want to use annotations
            #serializer: { enabled: true }

    .. code-block:: xml

        <!-- app/config/config.xml -->
        <?xml version="1.0" encoding="UTF-8"?>
        <container xmlns="http://symfony.com/schema/dic/services"
            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
            xmlns:framework="http://symfony.com/schema/dic/symfony"
            xsi:schemaLocation="http://symfony.com/schema/dic/services
                https://symfony.com/schema/dic/services/services-1.0.xsd
                http://symfony.com/schema/dic/symfony
                https://symfony.com/schema/dic/symfony/symfony-1.0.xsd">
            <framework:config>
                <!-- ... -->
                <framework:serializer enable-annotations="true"/>
                <!--
                Alternatively, if you don't want to use annotations
                <framework:serializer enabled="true"/>
                -->
            </framework:config>
        </container>

    .. code-block:: php

        // app/config/config.php
        $container->loadFromExtension('framework', [
            // ...
            'serializer' => [
                'enable_annotations' => true,
                // Alternatively, if you don't want to use annotations
                //'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:

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

use Symfony\Bundle\FrameworkBundle\Controller\Controller;
use Symfony\Component\Serializer\SerializerInterface;

class DefaultController extends Controller
{
    public function indexAction(SerializerInterface $serializer)
    {
        // keep reading for usage examples
    }
}

Adding Normalizers and Encoders

Once enabled, the serializer service will be available in the container. It comes with a set of useful :ref:`encoders <component-serializer-encoders>` and :ref:`normalizers <component-serializer-normalizers>`.

Encoders supporting the following formats are enabled:

JSON: :class:`Symfony\\Component\\Serializer\\Encoder\\JsonEncoder`
XML: :class:`Symfony\\Component\\Serializer\\Encoder\\XmlEncoder`
CSV: :class:`Symfony\\Component\\Serializer\\Encoder\\CsvEncoder`
YAML: :class:`Symfony\\Component\\Serializer\\Encoder\\YamlEncoder`

As well as the following normalizers:

:class:`Symfony\\Component\\Serializer\\Normalizer\\ObjectNormalizer` to handle typical data objects
:class:`Symfony\\Component\\Serializer\\Normalizer\\DateTimeNormalizer` for objects implementing the :phpclass:`DateTimeInterface` interface
:class:`Symfony\\Component\\Serializer\\Normalizer\\DataUriNormalizer` to transform :phpclass:`SplFileInfo` objects in Data URIs
:class:`Symfony\\Component\\Serializer\\Normalizer\\JsonSerializableNormalizer` to deal with objects implementing the :phpclass:`JsonSerializable` interface
:class:`Symfony\\Component\\Serializer\\Normalizer\\ArrayDenormalizer` to denormalize arrays of objects using a format like MyObject[] (note the [] suffix)

Custom normalizers and/or encoders can also be loaded 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`, a faster alternative to the ObjectNormalizer when data objects always use getters (getXxx()), issers (isXxx()) or hassers (hasXxx()) to read properties and setters (setXxx()) to change properties:

.. configuration-block::

    .. code-block:: yaml

        # app/config/services.yml
        services:
            get_set_method_normalizer:
                class: Symfony\Component\Serializer\Normalizer\GetSetMethodNormalizer
                public: false
                tags: [serializer.normalizer]

    .. code-block:: xml

        <!-- app/config/services.xml -->
        <?xml version="1.0" encoding="UTF-8"?>
        <container xmlns="http://symfony.com/schema/dic/services"
            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
            xsi:schemaLocation="http://symfony.com/schema/dic/services
                https://symfony.com/schema/dic/services/services-1.0.xsd">

            <services>
                <service id="get_set_method_normalizer" class="Symfony\Component\Serializer\Normalizer\GetSetMethodNormalizer" public="false">
                    <tag name="serializer.normalizer"/>
                </service>
            </services>
        </container>

    .. code-block:: php

        // app/config/services.php
        use Symfony\Component\Serializer\Normalizer\GetSetMethodNormalizer;

        $container->register('get_set_method_normalizer', GetSetMethodNormalizer::class)
            ->setPublic(false)
            ->addTag('serializer.normalizer')
        ;

.. versionadded:: 3.4

    Support for hasser methods (``hasXxx()``) in ``GetSetMethodNormalizer`` was
    introduced in Symfony 3.4. In previous Symfony versions only getters (``getXxx()``)
    and issers (``isXxx()``) were supported.

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 -->
        <?xml version="1.0" encoding="UTF-8"?>
        <container xmlns="http://symfony.com/schema/dic/services"
            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
            xmlns:framework="http://symfony.com/schema/dic/symfony"
            xsi:schemaLocation="http://symfony.com/schema/dic/services
                https://symfony.com/schema/dic/services/services-1.0.xsd
                http://symfony.com/schema/dic/symfony
                https://symfony.com/schema/dic/symfony/symfony-1.0.xsd">

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

    .. code-block:: php

        // app/config/config.php
        $container->loadFromExtension('framework', [
            // ...
            'serializer' => [
                '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:

$json = $serializer->serialize(
    $someObject,
    'json', ['groups' => ['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. By default, the serializer uses the cache.system cache pool which is configured using the :ref:`cache.system <reference-cache-system>` option.

Enabling a Name Converter

The use of a :ref:`name converter <component-serializer-converting-property-names-when-serializing-and-deserializing>` service can be defined in the configuration using the :ref:`name_converter <reference-serializer-name_converter>` option.

The built-in :ref:`CamelCase to snake_case name converter <using-camelized-method-names-for-underscored-attributes>` can be enabled by using the serializer.name_converter.camel_case_to_snake_case value:

.. configuration-block::

    .. code-block:: yaml

        # app/config/config.yml
        framework:
            # ...
            serializer:
                name_converter: 'serializer.name_converter.camel_case_to_snake_case'

    .. code-block:: xml

        <!-- app/config/config.xml -->
        <framework:config>
            <!-- ... -->
            <framework:serializer name-converter="serializer.name_converter.camel_case_to_snake_case"/>
        </framework:config>

    .. code-block:: php

        // app/config/config.php
        $container->loadFromExtension('framework', [
            // ...
            'serializer' => [
                'name_converter' => 'serializer.name_converter.camel_case_to_snake_case',
            ],
        ]);

Enabling Circular Reference Handler

The use of the :ref:`circular reference handler <component-serializer-handling-circular-references>` service can be defined in the configuration using the :ref:`circular_reference_handler <reference-serializer-circular_reference_handler>` option.

A circular reference handler service has to implement the magic __invoke($object) method, like in example:

class MyCircularReferenceHandler
{
    public function __invoke($object)
    {
        return $object->getName();
    }
}

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/*

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Files

serializer.rst

serializer.rst

How to Use the Serializer

Activating the Serializer

Using the Serializer Service

Adding Normalizers and Encoders

Using Serialization Groups Annotations

Enabling the Metadata Cache

Enabling a Name Converter

Enabling Circular Reference Handler

Going Further with the Serializer

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How to Use the Serializer

Activating the Serializer

Using the Serializer Service

Adding Normalizers and Encoders

Using Serialization Groups Annotations

Enabling the Metadata Cache

Enabling a Name Converter

Enabling Circular Reference Handler

Going Further with the Serializer