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File Content: `object_constructor.rst`

Object constructor
==================

Deserialize on existing objects
-------------------------------

By default, a brand new instance of target class is created during deserialization. To deserialize into an existing object, you need to perform the following steps.


1. Create new class which implements ObjectConstructorInterface

.. code-block:: php

    <?php declare(strict_types=1);

    namespace Acme\ObjectConstructor;

    use JMS\Serializer\Construction\ObjectConstructorInterface;
    use JMS\Serializer\DeserializationContext;
    use JMS\Serializer\Metadata\ClassMetadata;
    use JMS\Serializer\Visitor\DeserializationVisitorInterface;

    class ExistingObjectConstructor implements ObjectConstructorInterface
    {
        public const ATTRIBUTE = 'deserialization-constructor-target';

        private $fallbackConstructor;

        public function __construct(ObjectConstructorInterface $fallbackConstructor)
        {
            $this->fallbackConstructor = $fallbackConstructor;
        }

        public function construct(DeserializationVisitorInterface $visitor, ClassMetadata $metadata, $data, array $type, DeserializationContext $context): ?object
        {
            if ($context->hasAttribute(self::ATTRIBUTE)) {
                return $context->getAttribute(self::ATTRIBUTE);
            }

            return $this->fallbackConstructor->construct($visitor, $metadata, $data, $type, $context);
        }
    }


2. Register ExistingObjectConstructor.

You should pass ExistingObjectConstructor to DeserializationGraphNavigatorFactory constructor.


3. Add special attribute to DeserializationContext

.. code-block:: php

    $context = DeserializationContext::create();
    $context->setAttribute('deserialization-constructor-target', $document);
    $serializer->deserialize($data, get_class($document), 'json');

Name	Size	Permission
arrays.rst	2398 bytes	0644
exclusion_strategies.rst	11448 bytes	0644
object_constructor.rst	1850 bytes	0644
stdclass.rst	650 bytes	0644

File Content: object_constructor.rst

File Content: `object_constructor.rst`