SelectListItem中的Selected属性永远不会起作用(DropDownListFor)

Question

我在选择DropDownList的值时遇到问题.我一直在阅读所有类似的帖子,我无法得到解决方案.

实际的方法对我来说似乎非常好,因为我可以检查SelectList中的字段:

var selectList = new List<SelectListItem>(
    from variable in someKindOfCollection
    select new SelectListItem
        {
            Selected = variable.Property == selection,
            Text = variable.Property,
            Value = variable.Property
        });

据说,这给了我完全的控制权.在构建了selectList之后,我可以使用调试器检查变量.一切都很好,其中一个标有"Selected"属性.

然后我使用DropDownListFor来显示视图:

@Html.DropDownListFor(
    g => g.SomePropertyInModel , selectList, new { @class = "cssClass" })

但它没有用,从来没有..."渲染"下拉列表,但没有选择任何东西.

非常感谢 :)

新示例首先,我要道歉.我一直在隐藏信息,当然是完全无意的.所有代码都发生在Razor For循环中:

@foreach (var loopVariable in Model.Collection)
{
    if (Model.SomeCondition != null)
    {
        selection = someValue;
    }

    var selectList = new List<SelectListItem>(
      from variable in someKindOfCollection
      select new SelectListItem
    {
        Selected = variable.Property == selection,
        Text = variable.Property,
        Value = variable.Property
    });

    @Html.DropDownListFor(
        g => g.SomePropertyInModel , selectList, new { @class = "cssClass" })

}

那么,selectList是导致行为的局部变量的事实？对不起,我没想到就是这样.

Answer 1

我建议使用视图模型：

\n\n

public ActionResult Index()\n{\n    var model = new MyViewModel\n    {\n        // this will preselect the item with value = "2.400 \xe2\x82\xac" in the collection\n        SelectedValue = "2.400 \xe2\x82\xac",\n\n        Values = someKindOfCollection\n    };\n    return View(model);\n}\n

\n\n

并在视图中：

\n\n

@Html.DropDownListFor(\n    g => g.SelectedValue, \n    new SelectList(Model.Values, "SomePropertyForValue", "SomePropertyForText"), \n    new { @class = "cssClass" }\n)\n

\n