/**
  * query if editable for current user
  */
 static function getEditableById($id)
 {
     if ($tp = TaskPerson::getById(intval($id))) {
         if ($p = Project::getById($tp->project)) {
             if ($p->validateEditItem($tp)) {
                 return $tp;
             }
         }
     }
     return NULL;
 }