Question

我在MVC应用程序中有一个表单。回发返回模型，其中填充了所有值，但下拉值除外。这是我为下拉列表编写的代码，我到底哪里错了？

型号：

public class ViewModel : Model 
{
    public Dictionary<int, string> ServiceFocusList { get; set; }
    public int ServiceFocus { get; set; }
}

查看：

@using
(Html.BeginForm("SaveServiceRequest","ServiceRequest",FormMethod.Post))
{
    var AddLotLink = Url.Action("SaveServiceRequest", "ServiceRequest");
    var labelCol = "control-label col-md-4";
    @Html.LabelFor(model => model.ServiceFocusList, new { @class = @labelCol })
    @Html.ValidationMessageFor(model => model.ServiceFocusList)
    @Html.DropDownListFor(model => model.ServiceFocusList ,new SelectList(Model.ServiceFocusList,"Key",
     "Value", Model.ServiceFocus), "Select a Service Focus")
    <input type="submit" id="AddLotBtn" value="Add A Lot" class="saveDraft btn btn-default" urllink="@AddLotLink" />
}

控制器：

public ActionResult SaveServiceRequest(ViewModel model, long? lotId)
{
    //At this point both model.ServiceFocusList and model.ServiceFocus are null
    ServiceRequestSupport.SaveServiceRequest(model);
    RedirectToAction("CreateLotOffSR", "Lot", new {area = "Lot", model.ID});
}

Answer 1

DropDownListFor的第一个参数应该标识包含所选值的属性。你想要这个：

@Html.DropDownListFor(model => model.ServiceFocus, new SelectList(Model.ServiceFocusList,"Key",
 "Value", Model.ServiceFocus), "Select a Service Focus")

Answer 2

在视图中将DropdownList更改为以下内容，您将其绑定到字典而不是包含所选值的属性。

@Html.DropDownListFor(model => model.ServiceFocus ,new SelectList(Model.ServiceFocusList,"Key",
     "Value", Model.ServiceFocus), "Select a Service Focus")

html.dropdownlist不会在表单中回发到控制器

2 个答案: