MVC3 DropDownList + ViewBag 问题 [英] MVC3 DropDownList + ViewBag issue

问题描述

此代码工作正常

List<StateModelView> stateList = (from x in db.States
                                select new StateModelView {
                                    ID = x.ID,
                                    StateName = x.StateName
                                }).OrderBy(w => w.StateName).ToList();

ViewBag.StateList = new SelectList(stateList, "ID", "StateName");

在 HTML 下我有

under HTML I have

 @Html.DropDownList("StateList", ViewBag.StateList)

无论如何我得到了错误

CS1973:System.Web.Mvc.HtmlHelper"没有名为DropDownList"的适用方法，但似乎具有该名称的扩展方法.不能动态调度扩展方法.考虑强制转换动态参数或在没有扩展方法语法的情况下调用扩展方法.

我该如何解决?

推荐答案

ViewBag 是一个 dynamic 对象，不能直接从您的视图中使用(这基本上就是错误所说的).你需要投射它:

The ViewBag is a dynamic object, which cannot be used directly from your View (that is basically what the error is saying). You'll need to cast it:

@Html.DropDownList("StateList", (SelectList) ViewBag.StateList)

另一种选择是使用 ViewData，尽管它也可能需要强制转换.

Another option would be to use ViewData though it may also require casting.

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