我想创建一个以单个下拉列表开头的索引页面。一旦用户选择了一个类别,就会出现第二个下拉列表(通过 Ajax 调用),允许用户选择要编辑的模型项目。但是,使用我的控制器中的代码并在下面查看,我收到以下错误
The model item passed into the dictionary is of type 'System.Collections.Generic.List'1[Monet.Models.DropDownValues]', but this dictionary requires a model item of type 'Monet.Models.DropDownValues'.
控制器
    public ActionResult Index()
    {
        //redirect if security is not met. 
        if (!Security.IsAdmin(User)) return RedirectToAction("Message", "Home", new { id = 1 });
        var dropDownValues =  (from b in db.DropDownValues
                              orderby b.Model
                              select b.Model).Distinct();
        ViewBag.CategoryOptions = new SelectList(dropDownValues, "Model", "Model");
        return View(db.DropDownValues.ToList());
    }
看法
@model Monet.Models.DropDownValues
@{
    ViewBag.Title = "Monet Administration";
}
<h2>Monet Administration</h2>
Update values for drop down boxes
<div>
    <span style="float: left;">
        <div class="editor-label">
        @Html.LabelFor(model => model.Model)
        </div>
        <div class="editor-field">
        @Html.DropDownList("Categories", (SelectList)ViewBag.CategoryOptions, "")
        @Html.ValidationMessageFor(model => model.Model)
        </div>
    </span>
    <div style="clear: both;"></div>
</div>