jfu-1.0.x-dev/src/Plugin/rest/resource/BlockContentIdResource.php

<?php

namespace Drupal\jfu\Plugin\rest\resource;

use Drupal\rest\Plugin\ResourceBase;
use Drupal\rest\ResourceResponse;
use Drupal\Core\Cache\CacheableMetadata;

/**
  * Provides a Block Get Block Content Id resource
  *
  * @RestResource (
  *   id = "block_content_id_resource",
  *   label = @Translation("Block Content ID Resource"),
  *   uri_paths = {
  *     "canonical" = "/jfu_rest_api/block_content_id/{string}"
  *   }
  * )
 **/

class BlockContentIdResource extends ResourceBase {

  /**
   * Responds to entity GET requests.
   * @return \Drupal\rest\ResourceResponse
   */
  public function get($string) {
    $data = [];
    if (!empty($string)) {
      $plugin_id = base64_decode($string);
      if (!empty($plugin_id)) {
        $cv_array = explode(':', $plugin_id);
        if (isset($cv_array[1]) && !empty($cv_array[1])) {
          $entity_type_manager = \Drupal::service('entity_type.manager');
          $block_content = $entity_type_manager->getStorage('block_content')->loadByProperties([
            'uuid' => $cv_array[1],
          ]);

          if (!empty($block_content)) {
            $block_content = reset($block_content);
            $data['bcid'] = $block_content->id();
            $data['bc_link'] = $block_content->toUrl()->toString(TRUE)->getGeneratedUrl();
          }
        }
      }
    }

    //Add cache tags.
    $cache_metadata = new CacheableMetadata();
    $cache_metadata->addCacheTags(['block_content_list']);

    //Attach the cache metadata to the response.
    $response = new ResourceResponse($data);
    $response->addCacheableDependency($cache_metadata);

    return $response;
  }
}