CacheTestController.php

<?php

namespace Drupal\cache_test\Controller;

use Drupal\Core\Url;

/**
 * Controller routines for cache_test routes.
 */
class CacheTestController {
    
    /**
     * Early renders a URL to test bubbleable metadata bubbling.
     */
    public function urlBubbling() {
        $url = Url::fromRoute('<current>')->setAbsolute();
        return [
            '#markup' => 'This URL is early-rendered: ' . $url->toString() . '. Yet, its bubbleable metadata should be bubbled.',
        ];
    }
    
    /**
     * Bundle listing tags invalidation.
     *
     * @param string $entity_type_id
     *   The entity type ID.
     * @param string $bundle
     *   The bundle.
     *
     * @return array
     *   Renderable array.
     */
    public function bundleTags($entity_type_id, $bundle) {
        $storage = \Drupal::entityTypeManager()->getStorage($entity_type_id);
        $entity_ids = $storage->getQuery()
            ->condition('type', $bundle)
            ->execute();
        $page = [];
        $entities = $storage->loadMultiple($entity_ids);
        foreach ($entities as $entity) {
            $page[$entity->id()] = [
                '#markup' => $entity->label(),
            ];
        }
        $page['#cache']['tags'] = [
            $entity_type_id . '_list:' . $bundle,
        ];
        return $page;
    }

}