public function getQualifiedParentKeyName()
    {
        if (is_array($this->localKey)) { //Check for multi-columns relationship
            return array_map(function ($k) {
                return $this->parent->getTable().'.'.$k;
            }, $this->localKey);
        } else {
            return $this->parent->getTable().'.'.$this->localKey;
        }
    }