public function findOneWhere($criteria, $returnType = Table::RETURN_MODEL) {
        $this->limit(1);
        $result = $this->findWhere($criteria, $returnType);
        if (is_array($result)) {
            $result = array_values($result);
            return ($returnType === Table::RETURN_JSON) ? json_encode($result[0])
                        : $result[0];
        }
        else if (is_object($result)) {
            return $result->first();
        }
    }