DependencySerializationTrait.php

<?php

namespace Drupal\Core\DependencyInjection;

use Drupal\Component\DependencyInjection\ReverseContainer;
use Drupal\Core\Entity\EntityStorageInterface;
use Drupal\Core\StringTranslation\TranslatableMarkup;

/**
 * Provides dependency injection friendly methods for serialization.
 */
trait DependencySerializationTrait {
    
    /**
     * An array of service IDs keyed by property name used for serialization.
     *
     * @var array
     */
    // phpcs:ignore Drupal.Classes.PropertyDeclaration, Drupal.NamingConventions.ValidVariableName.LowerCamelName
    protected $_serviceIds = [];
    
    /**
     * An array of entity type IDs keyed by the property name of their storages.
     *
     * @var array
     */
    // phpcs:ignore Drupal.Classes.PropertyDeclaration, Drupal.NamingConventions.ValidVariableName.LowerCamelName
    protected $_entityStorages = [];
    
    /**
     * {@inheritdoc}
     */
    public function __sleep() {
        $vars = get_object_vars($this);
        try {
            $container = \Drupal::getContainer();
            $reverse_container = $container->get(ReverseContainer::class);
            foreach ($vars as $key => $value) {
                if (!is_object($value) || $value instanceof TranslatableMarkup) {
                    // Ignore properties that cannot be services.
                    continue;
                }
                if ($value instanceof EntityStorageInterface) {
                    // If a class member is an entity storage, only store the entity type
                    // ID the storage is for, so it can be used to get a fresh object on
                    // unserialization. By doing this we prevent possible memory leaks
                    // when the storage is serialized and it contains a static cache of
                    // entity objects. Additionally we ensure that we'll not have multiple
                    // storage objects for the same entity type and therefore prevent
                    // returning different references for the same entity.
                    $this->_entityStorages[$key] = $value->getEntityTypeId();
                    unset($vars[$key]);
                }
                elseif ($service_id = $reverse_container->getId($value)) {
                    // If a class member was instantiated by the dependency injection
                    // container, only store its ID so it can be used to get a fresh object
                    // on unserialization.
                    $this->_serviceIds[$key] = $service_id;
                    unset($vars[$key]);
                }
            }
        } catch (ContainerNotInitializedException $e) {
            // No container, no problem.
        }
        return array_keys($vars);
    }
    
    /**
     * {@inheritdoc}
     */
    public function __wakeup() {
        // Avoid trying to wakeup if there's nothing to do.
        if (empty($this->_serviceIds) && empty($this->_entityStorages)) {
            return;
        }
        $container = \Drupal::getContainer();
        foreach ($this->_serviceIds as $key => $service_id) {
            $this->{$key} = $container->get($service_id);
        }
        $this->_serviceIds = [];
        if ($this->_entityStorages) {
            
            /** @var \Drupal\Core\Entity\EntityTypeManagerInterface $entity_type_manager */
            $entity_type_manager = $container->get('entity_type.manager');
            foreach ($this->_entityStorages as $key => $entity_type_id) {
                $this->{$key} = $entity_type_manager->getStorage($entity_type_id);
            }
        }
        $this->_entityStorages = [];
    }

}