使用用户

Question

我想让我的模型与ASP.NET MVC 5中的Identity系统中的用户相关联，而不是 Employee 。我的问题是，我似乎无法弄清楚@ Html.DropDownList背后的魔力......我正在拉我的头发。这是我的ViewModel：

public class TicketViewModel
{
    [Display(Name="ID#")]
    public int TicketId { get; set; }
    public int EmployeeId { get; set; }
    public int ShopId { get; set; }
    public int UserId { get; set; }
    public int ApplicationUserId { get; set; }
    public string Description { get; set; }
    public string Status { get; set; }

    public EmployeeViewModel Employee { get; set; }
    public ShopViewModel Shop { get; set; }
    public TotsUser User { get; set; }
}

和TicketController方法：

// GET: /Ticket/Edit/5
public ActionResult Edit(int? id)
    {
        if (id == null)
        {
            return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
        }
        Ticket ticket = db.Tickets.Find(id);
        if (ticket == null)
        {
            return HttpNotFound();
        }

        TicketViewModel ticketVM = Mapper.Map(ticket, new TicketViewModel());

        ViewBag.EmployeeId = new SelectList(db.Employees, "EmployeeId", "Name", ticketVM.EmployeeId);
        ViewBag.ShopId = new SelectList(db.Shops, "ShopId", "Name", ticketVM.ShopId);
        ViewBag.UserListing = new SelectList(db.Users, "Id", "UserName", ticketVM.UserId);

        return View(ticketVM);
    }

视图（有问题的部分）

    <div class="form-group">
        @Html.LabelFor(model => model.EmployeeId, "EmployeeId", new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            @Html.DropDownList("EmployeeId", String.Empty)
            @Html.ValidationMessageFor(model => model.EmployeeId)
        </div>
    </div>

    <div class="form-group">
        @Html.LabelFor(model => model.UserId, "UserId", new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            @* @Html.DropDownList("UserId", String.Empty) *@
            @Html.DropDownList("UserId", @ViewBag.UserListing, null);
            @Html.ValidationMessageFor(model => model.UserId)
        </div>
    </div>

我甚至无法解释它如何与 EmployeeId 一起使用。这是脚手架为我的原始模型生成它的方式。它填充EmployeeId就好了。有人可以解释一下使用@Html.DropDownList助手进行的黑暗魔法并解释为什么我不能让DropDownList填充任何东西吗？

Answer 1

您可以尝试更改

ViewBag.UserListing = new SelectList(db.Users, "Id", "UserName", ticketVM.UserId);

到

ViewBag.UserId = new SelectList(db.Users, "Id", "UserName", ticketVM.UserId);

或更改

@Html.DropDownList("UserId", @ViewBag.UserListing, null);

到

@Html.DropDownList("UserId", (SelectList)@ViewBag.UserListing);

无论您使用哪种方法

，这都是错误的

@Html.DropDownList("UserId", @ViewBag.UserListing, null);

你必须告诉助手什么类型的对象@ViewBag.UserListing。在您的情况下，它将是(SelectList)@ViewBag.UserListing