asp.net-mvc – 为Cascade子列表构建一个空的MVC DropdownListFo

实际看法：

<div id="makes">
        @Html.DropDownListFor(m => m.Make_Id,Model.MakeList,HeelpResources.DropdownlistMakeFirstRecord)
    </div>
    <div id="models">
        @Html.DropDownListFor(m => m.Model_Id,Model.ModelList,HeelpResources.DropdownlistModelFirstRecord)
    </div>

实际的控制器(要工作，我必须构建一个空的SelectedList，但它似乎很奇怪，必须这样做)：

public virtual ActionResult Create()
    {
        // Build the Dropdownlist for the Makes
        var makesDto = _makeService.ListAllMakes();
        var makesViewModel = Mapper.Map<IList<MakeDto>,IList<MakeViewModel>>(makesDto);

        // Build the Dropdownlist for the Models
        var makeId = -1;
        var modelsDto = _modelService.ListModelByMake(makeId);
        var modelsViewModel = Mapper.Map<IList<ModelDto>,IList<ModelViewModel>>(modelsDto);

        // Build the ViewModel to return to the View
        CreateAdViewModel viewModel = new CreateAdViewModel();
        viewModel.MakeList = new SelectList(makesViewModel,"ID","Name");
        viewModel.ModelList = new SelectList(modelsViewModel,"Name"); 

        return View(viewModel);
    }

有没有办法建立这样的东西：
@ Html.DropDownListFor(m => m.Model_Id，null)

并从控制器中删除//为模型构建下拉列表？

谢谢