public function getById($id, $cascade = false) {
        $result = self::getField($this->data, $id, null);
        if ($cascade && null !== $result && isset($this->one[$id])) {
            foreach ($this->one[$id] as $class => $foreignId) {
                $result = array_merge($class::getInstance()->getById($foreignId, $cascade), $result);
            }
        }
        return $result;
    }