private function convertFetchString($fetchMode){
        if (is_int($fetchMode)) return $fetchMode;

        switch($fetchMode){
            case "LAZY":
                return ClassMetadataInfo::FETCH_LAZY;
            case "EAGER":
                return ClassMetadataInfo::FETCH_EAGER;
            case "EXTRA_LAZY":
                return ClassMetadataInfo::FETCH_EXTRA_LAZY;
            default:
                return ClassMetadataInfo::FETCH_LAZY;
        }
    }