How to Use the Serializer
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Read the updated version of this page for Symfony 7.1 (the current stable version).
Serializing and deserializing to and from objects and different formats (e.g. JSON or XML) is a very complex topic. Symfony comes with a Serializer Component, 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 Serializer Component.
Activating the Serializer
2.3
The Serializer has always existed in Symfony, but prior to Symfony 2.3,
you needed to build the serializer
service yourself.
The serializer
service is not available by default. To turn it on, activate
it in your configuration:
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# app/config/config.yml
framework:
# ...
serializer: { enable_annotations: true }
# Alternatively, if you don't want to use annotations
#serializer: { enabled: true }
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<!-- 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
http://symfony.com/schema/dic/services/services-1.0.xsd
http://symfony.com/schema/dic/symfony
http://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>
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// app/config/config.php
$container->loadFromExtension('framework', array(
// ...
'serializer' => array(
'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 like the following:
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// 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
2.7
The ObjectNormalizer is enabled by default in Symfony 2.7. In prior versions, you needed to load your own normalizer.
Once enabled, the serializer
service will be available in the container
and will be loaded with two encoders
(JsonEncoder and
XmlEncoder) and the
ObjectNormalizer normalizer.
You can load normalizers and/or encoders by tagging them as serializer.normalizer and 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 GetSetMethodNormalizer:
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# app/config/services.yml
services:
get_set_method_normalizer:
class: Symfony\Component\Serializer\Normalizer\GetSetMethodNormalizer
public: false
tags:
- { name: serializer.normalizer }
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<!-- 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
http://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>
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// app/config/services.php
use Symfony\Component\Serializer\Normalizer\GetSetMethodNormalizer;
$container->register('get_set_method_normalizer', GetSetMethodNormalizer::class)
->setPublic(false)
->addTag('serializer.normalizer')
;
Using Serialization Groups Annotations
2.7
Support for serialization groups was introduced in Symfony 2.7.
Enable serialization groups annotation with the following configuration:
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# app/config/config.yml
framework:
# ...
serializer:
enable_annotations: true
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<!-- 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
http://symfony.com/schema/dic/services/services-1.0.xsd
http://symfony.com/schema/dic/symfony
http://symfony.com/schema/dic/symfony/symfony-1.0.xsd">
<framework:config>
<!-- ... -->
<framework:serializer enable-annotations="true" />
</framework:config>
</container>
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// app/config/config.php
$container->loadFromExtension('framework', array(
// ...
'serializer' => array(
'enable_annotations' => true,
),
));
Next, add the @Groups annotations to your class and choose which groups to use when serializing:
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$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
orserialization.xml
file in theResources/config/
directory of a bundle; - All
*.yml
and*.xml
files in theResources/config/serialization/
directory of a bundle.
Enabling the Metadata Cache
2.7
Serializer metadata and the ability to cache them were introduced in Symfony 2.7.
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.
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# app/config/config_prod.yml
framework:
# ...
serializer:
cache: serializer.mapping.cache.apc
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<!-- app/config/config_prod.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
http://symfony.com/schema/dic/services/services-1.0.xsd
http://symfony.com/schema/dic/symfony
http://symfony.com/schema/dic/symfony/symfony-1.0.xsd">
<framework:config>
<!-- ... -->
<framework:serializer cache="serializer.mapping.cache.apc" />
</framework:config>
</container>
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// app/config/config_prod.php
$container->loadFromExtension('framework', array(
// ...
'serializer' => array(
'cache' => 'serializer.mapping.cache.apc',
),
));
Enabling a Name Converter
2.8
The name_converter
option was introduced in Symfony 2.8.
The use of a name converter service can be defined in the configuration using the name_converter option.
The built-in CamelCase to snake_case name converter
can be enabled by using the serializer.name_converter.camel_case_to_snake_case
value:
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# app/config/config.yml
framework:
# ...
serializer:
name_converter: 'serializer.name_converter.camel_case_to_snake_case'
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<!-- app/config/config.xml -->
<framework:config>
<!-- ... -->
<framework:serializer name-converter="serializer.name_converter.camel_case_to_snake_case" />
</framework:config>
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// app/config/config.php
$container->loadFromExtension('framework', array(
// ...
'serializer' => array(
'name_converter' => 'serializer.name_converter.camel_case_to_snake_case',
),
));
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.