Drupal 8怎样创建一个当前文章所含术语相关的文章列表区块

把下面代码放到自定义的模块目录里的src/Plugin/Block/SimilarContentBlock.php可实现等价功能：

 

<?php
namespace Drupal\howto\Plugin\Block;
use Drupal\Core\Block\BlockBase;
/**
 * Provides Similar content by taxonomy terms Block
 *
 * @Block(
 *   id = "similar_content_block",
 *   admin_label = @Translation("Similar Content"),
 * )
 */
class SimilarContentBlock extends BlockBase {
  /**
   * {@inheritdoc}
   */
  public function build() {
    $node = \Drupal::routeMatch()->getParameter('node');
    if ($node) {
      $nid = $node->id();
      $result = db_query_range('SELECT DISTINCT n.nid, n.title
          FROM node__field_tags t1
          INNER JOIN node__field_tags t2
          ON t1.entity_id = :nid AND t1.field_tags_target_id = t2.field_tags_target_id
          INNER JOIN node_field_data n
          ON t2.entity_id = n.nid
          WHERE n.nid != :nid
          ORDER BY n.created DESC', 0, 5,
          array(':nid' => $nid))->fetchAll();
      
      if (count($result) > 0) {
        $html = '<div class="block-views">';
        foreach ($result as $row) {
          $html .= '<div class="views-row">' . \Drupal::l($row->title,
              \Drupal\Core\Url::fromUri('entity:node/' . $row->nid)) .
              '</div>';
        }
        $html .= '</div>';

        return array(
            '#markup' => $html,
            '#cache' => array('contexts' => array('url')),
        );
      }
    }
    
    return array();
  }
}