如何使用ASP.NET MVC为View中的DropDownList设置默认值? [英] How to set default value for DropDownList in View using ASP.NET MVC?

问题描述

我正在尝试使用通过ViewBag传递给我的View的SelectList的数据在View中创建一个DropDownList:

I'm trying create a DropDownList in my View with data of a SelectList passed to my View using ViewBag:

ViewBag.OtherKeysList = new SelectList(list, "OtherKey");

在我的视图中，我创建一个WebGrid，其中的列表示此DropDownList，如下所示:

In my View i create a WebGrid with a column representing this DropDownList like this:

 grid.Column(columnName: "OtherKey", header: "OtherKey", format: @<text>@Html.DropDownList("OtherKey", (IEnumerable<SelectListItem>)ViewBag.OtherKeysList, new { @class = "extra-class" })</text>)))

但是，此列表仅使用列表中的第一项作为其默认值.如何将此列表的另一个值设置为其默认值?

However this list just uses the first item in the list as its default value. How to set another value of this list to its default value?

更新:

当我尝试以下代码时:

public ActionResult EditMapping(int id)
    {
        var list = new ListWithDuplicates();

        var v = (from a in dbProducts.MapperConfigs
                 where
                    a.MappingID.Equals(id)
                 select a
                   );

        foreach (var item in v)
        {
            list.Add(item.OtherKey, item.OtherKeyType);
        }

        ViewBag.TotalRows = v.Count();

        ViewBag.OtherKeysList = list.Select(x => new SelectListItem() { Text = x.Key, Value = x.Key, Selected = x.Key == "keyC" ? true : false });

        ViewBag.MappingName = (from a in dbProducts.MappingNames
                               where
                                  a.MappingID.Equals(id)
                               select a.Name
                   ).First();

        var data = v.ToList();
        return View(data);
    }

我得到以下结果:

无论如何配置:

我要实现的目标是:

Key1:具有默认值keyA的DropDownlist

Key1 : DropDownlist with default value keyA

Key2:默认值为keyB的下拉列表

Key2 : Dropdownlist with default value keyB

Key3:默认值为keyC的DropDownlist

Key3 : DropDownlist with default value keyC

Key4:默认值为keyD的下拉列表

Key4 : Dropdownlist with default value keyD

推荐答案

我假设您可以通过操作绑定到的list中的默认 SelectListItem 来获得所需的结果.选择列表.

I assume that you can achieve your desired result by manipulating the default SelectListItem in the list which is binded to SelectList.

var defaultItem = new SelectListItem()
{
   Value = 1,
   Text = "Default Item",
   Selected = true
};

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