Before adding entities to the export queue, Content Hub checks the eligibility of an entity, and dispatches the ContentHubPublisherEvents::ENQUEUE_CANDIDATE_ENTITY event. The subscribers of this event decide an entity's eligibility, and log the reason if it is ineligible to be enqueued to the export queue. You can export an ineligible entity as a dependency.

The following event subscribers that are enabled by default mark entities as ineligible based on the criteria:

Before adding entities to the export queue, Content Hub checks the eligibility of an entity, and dispatches the ContentHubPublisherEvents::ENQUEUE_CANDIDATE_ENTITY event. The subscribers of this event decide an entity's eligibility, and log the reason if it is ineligible to be enqueued to the export queue. You can export an ineligible entity as a dependency.

The following event subscribers that are enabled by default mark entities as ineligible based on the criteria:

Customizing ineligible entity list

You can create custom event subscribers that subscribe to the ​​ContentHubPublisherEvents ::ENQUEUE_CANDIDATE_ENTITY event. Acquia recommends that you set the eligibility of the entity inside such subscribers to false. For example, ContentHubEntityEligibilityEvent::setEligibility(FALSE). You can also provide your reason so that the system logs that information. For example, ContentHubEntityEligibilityEvent::setReason('Reason for marking entity ineligible');.

Sample custom event subscriber:

<?php

namespace Drupal\acquia_contenthub_publisher\EventSubscriber\EnqueueEligibility;

use Drupal\acquia_contenthub_publisher\ContentHubPublisherEvents;
use Drupal\acquia_contenthub_publisher\Event\ContentHubEntityEligibilityEvent;
use Drupal\Component\Uuid\Uuid;
use Symfony\Component\EventDispatcher\EventSubscriberInterface;

/**
 * Any entity that is missing its UUID shouldn't be enqueued.
 *
 * @package Drupal\acquia_contenthub_publisher\EventSubscriber\EnqueueEligibility
 */
class MissingUuid implements EventSubscriberInterface {

  /**
   * {@inheritdoc}
   */
  public static function getSubscribedEvents() {
    $events[ContentHubPublisherEvents::ENQUEUE_CANDIDATE_ENTITY][] =
      ['onEnqueueCandidateEntity', 1000];

    return $events;
  }

  /**
   * Skips entities missing its UUID.
   *
   * @param \Drupal\acquia_contenthub_publisher\Event\ContentHubEntityEligibilityEvent $event
   *   The event to determine entity eligibility.
   *
   * @throws \Exception
   */
  public function onEnqueueCandidateEntity(ContentHubEntityEligibilityEvent $event) {
    $entity = $event->getEntity();

    if (!Uuid::isValid($entity->uuid())) {
      $event->setEligibility(FALSE);
      $event->setReason('Missing entity uuid.');
      $event->stopPropagation();
    }
  }

}