Как не чистить кэш всего сайта?

<?php
switch($modx->event->name) {
  case 'OnDocFormRender':
    $resource->set('syncsite', 0);
  break;

  case 'OnDocFormSave':
    if ($modx->event->params['mode'] != 'upd') {return;}
    $resource->_contextKey = $resource->context_key;
    $cache = $modx->cacheManager->getCacheProvider($modx->getOption('cache_resource_key', null, 'resource'));
    $key = $resource->getCacheKey();
    $cache->delete($key, array('deleteTop' => true));
    $cache->delete($key);
  break;
}