update menu item parent and weight

update menu item parent

 
/**
   * @param string $linkuri
   * @param string $menuname
   * @return Drupal\menu_link_content\Entity\MenuLinkContent
   * An array of menu link content objects
   */
  function getMenuLinkContent($linkuri, $menuname) {
    return \Drupal::entityTypeManager()->getStorage('menu_link_content')->loadByProperties(
      [ 
        'link__uri' => $linkuri ,
        'menu_name' => $menuname,
      ]
    );
  }

try {
  // menu name.
  // @to do change menu name
  $menuname = "main";
  // child entity id is the entity id whose parent menu link id has to be replaced.
  // @to do change child entity id
  $childentityid = 108;
  $childlinkuri = "entity:node/" . $childentityid;
  // @to do get childweight from d7 menu link.
  $childweight = 0;
  // child menu link content
  $cmlc = getMenuLinkContent($childlinkuri, $menuname);
  // if we found child menu link then find parent menu link. 
  If (!empty($cmlc)) {
     // @to do change the parent entity id.
     $parententityid = 124;
     $parentlinkuri = "entity:node/" . $parententityid;
     // parent menu link content
     $pmlc = getMenuLinkContent($parentlinkuri, $menuname);
     if (!empty($pmlc)) {
       // parent menu link plugin id
       $pmlpi = reset($pmlc)->getPluginId();
     }
     // get first menulink item ( we are assuming that each node will have only one menu link)
     $cmlc = reset($cmlc);
     // parent menu link plugin found then only update child menu link parent field.
     if ($pmlpi) {
       $cmlc->set("parent", $pmlpi);
     }
     $cmlc->set("weight", $childweight);
     $cmlc->save();
  }
}
catch (Exception $e) {
   \Drupal::logger('widget')->error($e->getMessage());
}