C#使用带有枚举的If语句

我希望根据从枚举器的下拉列表中选择的选项显示不同的viewbag消息，但我不知道如何做到这一点。我使用一个视图模型并通过控制器传递数据，这里是viewmodel和类，解释了如何使用带有ViewModels/Enumerator的if语句将非常有益。我尝试过分配变量，但我意识到我所做的只是说THIS is THIS，所以这不会从Orders Postage枚举中获得数据。感谢任何帮助和解释，仍在学习中。

ViewModel；

{
    public class MyOrdersViewModel
    {
        public int OrderId { get; set; }
        public System.DateTime OrderDate { get; set; }
        public string FirstName { get; set; }
        public string LastName { get; set; }
        public string Address { get; set; }
        public string City { get; set; }
        public string PostalCode { get; set; }
        public decimal Total { get; set; }
        public bool HasBeenShipped { get; set; }
        public Postage? PostageList { get; set; }
        public List<MyOrderDetails> Details { get; set; }
    }
    public class MyOrderDetails
    {
        public string Title { get; set; }
        public string Colour { get; set; }
        public int Quantity { get; set; }
        public decimal UnitPrice { get; set; }
    }
}

控制器；

        public ActionResult Index(Order order)
        {
            string currentUser = this.User.Identity.GetUserName();
            List<T_shirt_Company_v3.ViewModels.MyOrdersViewModel> list = (from o in new TshirtStoreDB().Orders
                    .Where(o => o.Username == currentUser)
                    .OrderByDescending(o => o.OrderDate)
                    .Select(o => new MyOrdersViewModel()
                    {
                        OrderId = o.OrderId,
                        Address = o.Address,
                        FirstName = o.FirstName,
                        LastName = o.LastName,
                        City = o.City,
                        OrderDate = o.OrderDate,
                        PostalCode = o.PostalCode,
                        Total = o.Total,
                        HasBeenShipped = o.HasBeenShipped,
                        PostageList = o.PostageList,
                        Details = (from d in o.OrderDetails
                                   select new MyOrderDetails
                                   {
                                       Colour = d.Product.Colour,
                                       Quantity = d.Quantity,
                                       Title = d.Product.Title,
                                       UnitPrice = d.UnitPrice
                                   }).ToList()
                    }).ToList()
                                                                          select o).ToList();
            //@ViewBag.PostageStatus
            //ViewBag.ShippedMessage = list.Where(w => w.HasBeenShipped).Any() ? "Order has been shipped" : "Order is being processed";
            Postage value = Postage.FirstClass;
            Postage value2 = Postage.StandardDelivery;
            Postage value3 = Postage.TwentyFourHour;
            if (value == Postage.FirstClass)
            {
                ViewBag.PostageStatus = ("First Class");
            }
            else
            {
                ViewBag.PostageStatus = (" Error ");
            }
            if (value2 == Postage.StandardDelivery)
            {
                ViewBag.PostageStatus = ("Standard Delivery");
            }
            if (value3 == Postage.StandardDelivery)
            {
                ViewBag.PostageStatus = ("24 hour delivery");
            }
return View(list);
        }

订单类别

namespace T_shirt_Company_v3.Models
{
    //[Bind(Exclude = "OrderId")]
    public partial class Order
    {
        [ScaffoldColumn(false)]
        public int OrderId { get; set; }
        [ScaffoldColumn(false)]
        public System.DateTime OrderDate { get; set; }
        [ScaffoldColumn(false)]
        [Remote("CheckUserName", "Account")]
        public string Username { get; set; }
        [Required]
        [StringLength(16, ErrorMessage = "Your name is too long")]
        [Display(Name = "First Name")]
        public string FirstName { get; set; }
        [Required(ErrorMessage = "Your last name is required.")]
        [StringLength(16, ErrorMessage = "Last name is too long.")]
        [Display(Name = "Last Name")]
        public string LastName { get; set; }
        [Required(ErrorMessage = "Address is required.")]
        public string Address { get; set; }
        [Required(ErrorMessage = "City is required.")]
        public string City { get; set; }
        [Required(ErrorMessage = "Postcode is required.")]
        [Display(Name = "Post Code")]
        public string PostalCode { get; set; }
        [Required(ErrorMessage = "Country is required.")]
        public string Country { get; set; }
        [Required(ErrorMessage = "Phone number is required.")]
        public string Phone { get; set; }
        [RegularExpression(@"[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+'.[A-Za-z]{2,4}", ErrorMessage = "Email doesn't look like a valid email address.")]
        public string Email { get; set; }
        [System.ComponentModel.DataAnnotations.Compare("Email")]
        [Display(Name = "Confirm your email address")]
        public string EmailConfirm { get; set; }

        [ScaffoldColumn(false)]
        public string PaymentTransactionId { get; set; }

        [ScaffoldColumn(false)]
        public bool HasBeenShipped { get; set; }
        [ScaffoldColumn(false)]
        //[ReadOnly(true)]
        public decimal Total { get; set; }
        [Required]
        [Range(0, 2, ErrorMessage = "Select a delivery method")]
        public Postage? PostageList { get; set; }
        public CardDetails cardDetails { get; set; }
        //public List<CardDetails> cardDetails { get; set; }
        public List<OrderDetail> OrderDetails { get; set; }
    }
    public enum Postage {[Display(Name = "Standard Delivery - Free")]StandardDelivery, [Display(Name = "First Class Delivery - £4.99")]FirstClass, [Display(Name = "24 Hour Delivery - £9.99")]TwentyFourHour }
}

switch (order.Postage.GetValueOrDefault())
{
    case Postage.StandardDelivery:
        ViewBag.PostageStatus = "Standard Delivery";
        break;
    case Postage.FirstClass:
        ViewBag.PostageStatus = "First Class";
        break;
    case Postage.TwentyFourHour:
        ViewBag.PostageStatus = "24 hour delivery";
        break;
    default:
        ViewBag.PostageStatus = "Error";
        break;
}