/**
  * Creates a Cart object based on a DB row.
  *
  * @param array $row The DB row containing cart data.
  * @return \VeryGoodTrip\Domain\Cart
  */
 protected function buildDomainObject($row)
 {
     $cart = new Cart();
     $cart->setId($row['cart_id']);
     $cart->setUser($this->userDAO->findById($row['user_id']));
     $cart->setTrip($this->tripDAO->find($row['trip_id']));
     return $cart;
 }