Issue #3522779 by mglaman, phenaproxima, alexpott: Dispatch an event for...

      throw new ImportException('The uuid metadata must be specified.');

    }

    // Allow third-party code to modify the entity data before the entity is

    // created.

    $event = new PreEntityImportEvent($data);

    $data = ['_meta' => $event->metadata] + $this->eventDispatcher->dispatch($event)->data;

    $is_root = FALSE;

    // @see ::loadEntityDependency()

    if ($this->dependencies === NULL && !empty($data['_meta']['depends'])) {

<?php

declare(strict_types=1);

namespace Drupal\Core\DefaultContent;

use Symfony\Contracts\EventDispatcher\Event;

/**

 * Event dispatched before an entity is created during default content import.

 *

 * This event is dispatched for each entity before it is created from the

 * decoded data. Subscribers can modify the entity data (default and

 * translations) but not the metadata.

 */

final class PreEntityImportEvent extends Event {

  /**

   * The entity metadata.

   *

   * @var array<string, mixed>

   */

  public readonly array $metadata;

  public function __construct(public array $data) {

    $this->metadata = $data['_meta'];

    unset($this->data['_meta']);

  }

}

<?php

declare(strict_types=1);

namespace Drupal\KernelTests\Core\DefaultContent;

use Drupal\Core\DefaultContent\Finder;

use Drupal\Core\DefaultContent\Importer;

use Drupal\Core\DefaultContent\PreEntityImportEvent;

use Drupal\Core\Entity\EntityRepositoryInterface;

use Drupal\KernelTests\KernelTestBase;

use Drupal\Tests\user\Traits\UserCreationTrait;

use PHPUnit\Framework\Attributes\CoversClass;

use PHPUnit\Framework\Attributes\Group;

use PHPUnit\Framework\Attributes\RunTestsInSeparateProcesses;

use Symfony\Component\EventDispatcher\EventSubscriberInterface;

use Symfony\Contracts\EventDispatcher\EventDispatcherInterface;

/**

 * Tests the Default Content Importer.

 */

#[Group('DefaultContent')]

#[CoversClass(Importer::class)]

#[RunTestsInSeparateProcesses]

class ImporterTest extends KernelTestBase implements EventSubscriberInterface {

  use UserCreationTrait;

  /**

   * {@inheritdoc}

   */

  protected static $modules = ['system', 'user', 'entity_test'];

  /**

   * {@inheritdoc}

   */

  protected function setUp(): void {

    parent::setUp();

    $this->installEntitySchema('entity_test');

    $this->container->get(EventDispatcherInterface::class)

      ->addSubscriber($this);

  }

  /**

   * {@inheritdoc}

   */

  public static function getSubscribedEvents(): array {

    return [

      PreEntityImportEvent::class => 'onPreEntityImport',

    ];

  }

  /**

   * Modify entity data before it is imported.

   *

   * @param \Drupal\Core\DefaultContent\PreEntityImportEvent $event

   *   The event being handled.

   */

  public function onPreEntityImport(PreEntityImportEvent $event): void {

    self::assertSame('entity_test', $event->metadata['entity_type']);

    if ($event->metadata['uuid'] === '01234567-89ab-cdef-0123-456789abcdef') {

      $event->data['default']['name'] = [

        ['value' => 'Changed name'],

      ];

    }

    // Anything we put in `_meta` should be discarded.

    $event->data['_meta']['entity_type'] = 'This will be ignored.';

  }

  /**

   * Tests changing entity data upon import.

   */

  public function testChangeDataOnImport(): void {

    $this->setUpCurrentUser(admin: TRUE);

    $finder = new Finder($this->getDrupalRoot() . '/core/tests/fixtures/pre_entity_import_default_content');

    $this->container->get(Importer::class)->importContent($finder);

    $entity = $this->container->get(EntityRepositoryInterface::class)

      ->loadEntityByUuid('entity_test', '01234567-89ab-cdef-0123-456789abcdef');

    self::assertSame('Changed name', $entity?->label());

  }

}

_meta:

  version: '1.0'

  entity_type: entity_test

  uuid: 01234567-89ab-cdef-0123-456789abcdef

  bundle: entity_test

  default_langcode: en

default:

  name:

    -

      value: 'Test Entity One'

  created:

    -

      value: 1711638565

  user_id:

    -

      target_id: 1

  langcode:

    -

      value: en

_meta:

  version: '1.0'

  entity_type: entity_test

  uuid: 12345678-9abc-def0-1234-56789abcdef0

  bundle: entity_test

  default_langcode: en

default:

  name:

    -

      value: 'Simple Test Entity'

  created:

    -

      value: 1609459200

  user_id:

    -

      target_id: 1

  langcode:

    -

      value: en