/// <summary>
/// 购物结账并产生销售订单。
/// </summary>
/// <param name="customerID">需要结账并生成订单的客户的全局唯一标识。</param>
public SalesOrderDataObject Checkout(Guid customerID)
{
var user = userRepository.GetByKey(customerID);
var shoppingCart = shoppingCartRepository.FindShoppingCartByUser(user);
var salesOrder = domainService.CreateSalesOrder(user, shoppingCart);
return(Mapper.Map <SalesOrder, SalesOrderDataObject>(salesOrder));
}