cforge-2.0.x-dev/modules/cforge_import/src/DefaultContentDeleteSubscriber.php

<?php

namespace Drupal\cforge_import;

use Symfony\Component\EventDispatcher\EventSubscriberInterface;
use Drupal\migrate\Event\MigrateImportEvent;
use Drupal\Core\Entity\EntityTypeManager;


/**
 * Before importing, delete a module's default content
 * @todo this is not used anywhere.
 */
class DefaultContentDeleteSubscriber implements EventSubscriberInterface {

  /**
   * @var \Drupal\Core\Entity\ContentEntityStorageInterface
   */
  private $entityStorage;
  private $bundle;
  private $bundleKey;

  /**
   * @param EntityTypeManager $entity_type_manager
   * @param string $entity_type
   * @param string $bundle
   */
  function __construct(EntityTypeManager $entity_type_manager, $entity_type, $bundle = NULL) {
    $this->entityStorage = $entity_type_manager->getStorage($entity_type);
    if ($bundle) {
      $this->bundle = $bundle;
      $this->bundleKey = $this->entityStorage->getEntityType()->getKey('bundle');
    }
  }


  /**
   * {@inheritdoc}
   */
  public static function getSubscribedEvents() : array {
    return [
      //Drupal\migrate\Event\MigrateEvents::PRE_IMPORT
      'migrate.pre_import' => [['migratePreImport']],
    ];
  }

  /**
   * @param Drupal\migrate\Event\MigrateImportEvent $event
   */
  public function migratePreImport(MigrateImportEvent $event) {
    if ($this->bundleKey) {
      $entities = $this->entityStorage->loadByProperties([$this->bundleKey => $this->bundle]);
      \Drupal::messenger()->addStatus("Deleting $this->bundle ".\print_r(array_keys($entities), 1));
    }
    else {
      $entities = $this->entityStorage->loadMultiple();
    }
    foreach ($entities as $entity) {
      $entity->delete();
    }
  }


}