c# - 将 View 模型中的枚举绑定(bind)到 MVC

Question

每当我尝试创建工单时，我的工单优先级也很低。我已经为优先级设置了一个下拉列表，但票证上的优先级分配似乎不起作用。我怀疑它与我的 Views\Ticket\Create.cshtml 有关

我需要一些说明，看看我这样做是否正确:

两者都需要吗

在我的模型中，我有一个名为 Ticket 的类，它具有枚举优先级

public enum Priority
{
    Low, Med, High
}
public class Ticket
{
  ....
}

Configuration.cs(用于插入工单数据的片段)

var tickets = new List<Ticket>
{
    new Ticket {
        UserID = users.Single(s => s.LastName == "Wan").UserID,
        CategoryID = categories.Single(c => c.CategoryName == "Con-X" ).CategoryID,
        Issue = ("Con-X Login Error"),
        Priority = Priority.High
    },
    new Ticket {
        UserID = users.Single(s => s.LastName == "Wan").UserID,
        CategoryID = categories.Single(c => c.CategoryName == "Desktop" ).CategoryID,
        Issue = ("Can't remote access C0123"),
        Priority = Priority.Med
    },
};

在我的 View 模型 TicketVM 中，我还为优先级设置了枚举。由于我正在通过此配置我的票证:

            Ticket ticket = new Ticket
            {
                UserID = (int)WebSecurity.CurrentUserId,
                Issue = model.Issue,
                IssuedTo = model.IssuedTo,
                CategoryID = model.CategoryID,
                Priority = model.priority <-- ERROR
            };

错误:

Cannot implicitly convert type 'RecreationalServicesTicketingSystem.ViewModels.TicketVM.Priority' to 'RecreationalServicesTicketingSystem.Models.Priority'. An explicit conversion exists (are you missing a cast?) RecreationalServicesTicketingSystem

Views\Ticket\Create.cshtml

    <div class="form-group">
        @Html.DropDownListFor(m => m.priority, Model.PriorityList, "Please select the priority") 
    </div>

ViewModels\TicketVM.cs

public class TicketVM
{
    public int UserID { get; set; }
    [Required(ErrorMessage = "Please enter the description")]
    public string Issue { get; set; }
    [Display(Name = "Administrator")]
    [Required(ErrorMessage = "Please select the Administrator")]
    public int IssuedTo { get; set; }
    public IEnumerable<SelectListItem> AdministratorList { get; set; }
    public int CategoryID { get; set; }
    public IEnumerable<SelectListItem> CategoryList { get; set; }

    public enum Priority
    {
        LOW = 3,
        MED = 2,
        HIGH = 1,
    }

    public Priority priority { get; set; }
    public IEnumerable<SelectListItem> PriorityList
    {
        get
        {
            var priorityType = typeof(Priority);
            var priorityValues = Enum.GetValues(priorityType).Cast<Priority>();
            var converter = TypeDescriptor.GetConverter(priorityType);

            return
                from priorityValue in priorityValues
                select new SelectListItem
                {
                    Text = converter.ConvertToString(priorityValue),
                    Value = priorityValue.ToString(),
                };
        }
    }
}

TicketController.cs

public ActionResult Create()
{
    TicketVM model = new TicketVM();
    ConfigureViewModel(model);
    return View(model);
}

[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Create(TicketVM model)
{
    if (!ModelState.IsValid)
    {
        model.CategoryList = new SelectList(db.Categories, "CategoryID", "CategoryName");
        ConfigureViewModel(model);
        return View(model);
    }
    Ticket ticket = new Ticket
    {
        UserID = (int)WebSecurity.CurrentUserId,
        Issue = model.Issue,
        IssuedTo = model.IssuedTo,
        CategoryID = model.CategoryID,
        Priority = model.priority <-- ERROR
    };
    db.Tickets.Add(ticket);
    db.SaveChanges();
    return RedirectToAction("Index");
}

private void ConfigureViewModel(TicketVM model)
{
    IEnumerable<User> admins = db.Users.Where(u => u.IsAdministrator).OrderBy(u => u.LastName);
    model.AdministratorList = admins.Select(a => new SelectListItem
    {
        Value = a.UserID.ToString(),
        Text = string.Format("{0} {1}", a.FirstMidName, a.LastName)
    });
    IEnumerable<Category> categories = db.Categories.OrderBy(u => u.CategoryName);
    model.CategoryList = categories.Select(a => new SelectListItem
    {
        Value = a.CategoryID.ToString(),
        Text = a.CategoryName.ToString()
    });
}

Answer 1

enums在你的Ticket模型和 TicketVM型号不一样。

一个选择是在 TicketVM 中添加一个 using 语句这样你就可以使用 enum来自 RecreationalServicesTicketingSystem.Models (并删除 enum 类中的 TicketVM 定义)

@using RecreationalServicesTicketingSystem.Models
public class TicketVM
{
    ....
    public Priority priority { get; set; } // uses the enum from the Models assembly
}

另一种选择是从一个转换到另一个。由于您需要在对象初始值设定项中使用它，因此在 Controller 中创建一个私有(private)方法来转换值

private Models.Priority CastPriority(ViewModels.TicketVM.Priority value)
{
    Models.Priority priority = Models.Priority.Low;
    Enum.TryParse<Models.Priority>(value.ToString(), out priority);
    return priority;
}

在对象初始值设定项中

Ticket ticket = new Ticket
{
    ....
    CategoryID = model.CategoryID,
    Priority = CastPriority(model.priority)
};

旁注:您可以简化生成 IEnumerable<SelectListItem> 的代码到

public IEnumerable<SelectListItem> PriorityList
{
    get
    {
        return Enum.GetNames(typeof(Proprity)).Select(e => new SelectListItem() { Text = e, Value = e });
    }
}