protected function modifyModel(&$nodes) {
    $request = $this->getRequest();
    // TODO: put this into subclass ListController

    // remove all attributes except for display values
    if ($request->getBooleanValue('completeObjects', false) == false) {
      for($i=0,$count=sizeof($nodes); $i<$count; $i++) {
        $node = $nodes[$i];
        $displayValues = $request->hasValue('values') ? array_map('trim', explode(',', $request->getValue('values'))) :
          $node->getProperty('displayValues');
        $valueNames = array_merge($node->getValueNames(), $node->getRelationNames());
        foreach($valueNames as $name) {
          if (!in_array($name, $displayValues)) {
            $node->removeValue($name);
          }
        }
      }
    }
    // render values
    if ($request->getBooleanValue('translateValues', false) == true) {
      NodeUtil::translateValues($nodes);
    }
  }