serializer.md

Symfony Serializer Component

Docs

An array is used as an intermediary between objects and serialized contents. This way, encoders will only deal with turning specific formats into arrays and vice versa. The same way, Normalizers will deal with turning specific objects into arrays and vice versa.

composer require symfony/serializer

Serialize Entity

In a controller:

class BlogController extends AbstractController
{
    #[Route('/api/blog', name: 'app_api_blog')]
    public function index(BlogRepository $blogRepository): Response
    {
        $blogs = $blogRepository->getBlogs();

        return $this->json($blogs);
    }
}

Fix circular reference error

Modify config/services.yaml:

services:
    app.normalizer.object_normalizer:
        class: Symfony\Component\Serializer\Normalizer\ObjectNormalizer
        tags: ['serializer.normalizer']
        arguments:
            $defaultContext:
                circular_reference_handler: '@App\Serializer\CircularReferenceHandler'
                ignored_attributes: ['createdOn', 'updatedOn']

In ignored_attributes option we define what entity's fields should not be included in the output.

Add a handler src\Serializer\CircularReferenceHandler.php:

namespace App\Serializer;

class CircularReferenceHandler
{
    public function __invoke($object)
    {
        return $object->getId();
    }
}

Ignore entity's field

Via Ignore

File src/Entity/Blog.php:

namespace App\Entity;

use Symfony\Component\Serializer\Attribute\Ignore;

#[ORM\Entity(repositoryClass: BlogRepository::class)]
#[ORM\HasLifecycleCallbacks]
class Blog
{
    #[ORM\ManyToOne(cascade:['persist'], inversedBy: 'blogs')]
    #[Ignore]
    private ?User $user = null;

Via context param for json() method

In a controller:

  return $this->json($blogs, context: [AbstractNormalizer::IGNORED_ATTRIBUTES => [
          'category',
          'createdAt',
      ]
  ]);

Via Groups

Entity:

class Blog
{
    #[Groups(['groupOne'])]
    #[Assert\NotBlank]
    #[ORM\Column(length: 255)]
    private ?string $title = null;

Note: Add this Groups attribute to related entities to display their info.

Controller:

    return $this->json($blogs, context: [
        AbstractNormalizer::GROUPS => ['groupOne'],
    ]);

Fields marked with groupOne will be in the response.

Format attribute

Modify config/services.yaml - define callback for the field updatedAt:

services:
    app.normalizer.object_normalizer:
        class: Symfony\Component\Serializer\Normalizer\ObjectNormalizer
        tags: ['serializer.normalizer']
        arguments:
            $defaultContext:
                circular_reference_handler: '@App\Serializer\CircularReferenceHandler'
                ignored_attributes: ['createdOn', 'updatedOn']
                callbacks: {
                    'updatedAt': '@App\Serializer\UpdatedAtCallback',
                }

File src/Serializer/UpdatedAtCallback.php

class UpdatedAtCallback
{
    public function __invoke(null|string|DateTimeInterface $innerObject): DateTimeInterface|string|null
    {
        if ($innerObject === null) {
            return null;
        }

        if (!($innerObject instanceof DateTimeInterface)) {
            return $innerObject;
        }

        return $innerObject->format('Y-m-d H:i:s');
    }
}

Serialize Object

use Symfony\Component\Serializer\Encoder\JsonEncoder;
use Symfony\Component\Serializer\Encoder\XmlEncoder;
use Symfony\Component\Serializer\Normalizer\ObjectNormalizer;
use Symfony\Component\Serializer\Serializer;

$encoders = [new XmlEncoder(), new JsonEncoder()];
$normalizers = [new ObjectNormalizer()];

$serializer = new Serializer($normalizers, $encoders);

use App\Model\Person;

$person = new Person();
$person->setName('foo');
$person->setAge(99);
$person->setSportsperson(false);

$jsonContent = $serializer->serialize($person, 'json');

// $jsonContent contains {"name":"foo","age":99,"sportsperson":false,"createdAt":null}

echo $jsonContent; // or return it in a Response

The first parameter of the serialize() is the object to be serialized and the second is used to choose the proper encoder, in this case JsonEncoder.

Deserializing an Object

The information of the Person class is encoded in XML format:

use App\Model\Person;

$data = <<<EOF
<person>
    <name>foo</name>
    <age>99</age>
    <sportsperson>false</sportsperson>
</person>
EOF;

$person = $serializer->deserialize($data, Person::class, 'xml');

Encoders

Encoders turn arrays into formats and vice versa. They implement EncoderInterface for encoding (array to format) and DecoderInterface for decoding (format to array).

use Symfony\Component\Serializer\Encoder\JsonEncoder;
use Symfony\Component\Serializer\Encoder\XmlEncoder;
use Symfony\Component\Serializer\Serializer;

$encoders = [new XmlEncoder(), new JsonEncoder()];
$serializer = new Serializer([], $encoders);

Built-in Encoders

The Serializer component provides several built-in encoders:

• JsonEncoder. This class encodes and decodes data in JSON.
• XmlEncoder. This class encodes and decodes data in XML.
• YamlEncoder. This encoder encodes and decodes data in YAML. This encoder requires the Yaml Component.
• CsvEncoder. This encoder encodes and decodes data in CSV.