Menu.php

<?php

namespace Drupal\system\Entity;

use Drupal\Core\Entity\Attribute\ConfigEntityType;
use Drupal\Core\StringTranslation\TranslatableMarkup;
use Drupal\Core\Config\Entity\ConfigEntityBase;
use Drupal\Core\Entity\EntityStorageInterface;
use Drupal\system\MenuAccessControlHandler;
use Drupal\system\MenuInterface;
use Drupal\system\MenuStorage;

/**
 * Defines the Menu configuration entity class.
 */
class Menu extends ConfigEntityBase implements MenuInterface {
  
  /**
   * The menu machine name.
   *
   * @var string
   */
  protected $id;
  
  /**
   * The human-readable name of the menu entity.
   *
   * @var string
   */
  protected $label;
  
  /**
   * The menu description.
   *
   * @var string
   */
  protected $description;
  
  /**
   * The locked status of this menu.
   *
   * @var bool
   */
  protected $locked = FALSE;
  
  /**
   * {@inheritdoc}
   */
  public function getDescription() {
    return $this->description;
  }
  
  /**
   * {@inheritdoc}
   */
  public function isLocked() {
    return (bool) $this->locked;
  }
  
  /**
   * {@inheritdoc}
   */
  public static function preDelete(EntityStorageInterface $storage, array $entities) {
    parent::preDelete($storage, $entities);
    /** @var \Drupal\Core\Menu\MenuLinkManagerInterface $menu_link_manager */
    $menu_link_manager = \Drupal::service('plugin.manager.menu.link');
    foreach ($entities as $menu) {
      // Delete all links from the menu.
      $menu_link_manager->deleteLinksInMenu($menu->id());
    }
  }
  
  /**
   * {@inheritdoc}
   */
  public function save() {
    $return = parent::save();
    \Drupal::cache('menu')->deleteAll();
    // Invalidate the block cache to update menu-based derivatives.
    if (\Drupal::moduleHandler()->moduleExists('block')) {
      \Drupal::service('plugin.manager.block')->clearCachedDefinitions();
    }
    return $return;
  }
  
  /**
   * {@inheritdoc}
   */
  public function delete() {
    parent::delete();
    \Drupal::cache('menu')->deleteAll();
    // Invalidate the block cache to update menu-based derivatives.
    if (\Drupal::moduleHandler()->moduleExists('block')) {
      \Drupal::service('plugin.manager.block')->clearCachedDefinitions();
    }
  }

}