Question

好的，所以我得到了dropDown框，我有我的选项，如果我选择任何一个，我想写下提交的所选项目的价值，听起来很容易吗？好吧，每当我点击任何选项并提交它时，该值都显示在URL上，但我似乎无法将其写出来......

查看（Index.cshtml）：

<p>Dropdown Using viewbag with Html.DropDownList </p>
<br/>
<div>
        @using (Html.BeginForm("dropDown", "Home", FormMethod.Get))
    {
        @Html.DropDownList("ListItem")

        <button type="submit"></button>
    }

</div>

<p>@ViewBag.SelectedValue</p> //should print the value I selected but it does nothing...

Controller（HomeController.cs）：

public ActionResult Index()
    {
        List<SelectListItem> ObjItem = new List<SelectListItem>()
        {
      new SelectListItem {Text="Select",Value="0",Selected=true },
      new SelectListItem {Text="ASP.NET",Value="1" },
      new SelectListItem {Text="C#",Value="2"},
      new SelectListItem {Text="MVC",Value="3"},
      new SelectListItem {Text="SQL",Value="4" },
        };
        ViewBag.ListItem = ObjItem;

        return View("Index");
    }

    public ActionResult dropDown(List<SelectListItem> ListItem)
    {
        ViewBag.SelectedValue = ListItem[0].Value; //crossing fingers this has the value I want to print


        return this.View("Index");
    }

Answer 1

试试这个

查看（Index.cshtml）：

<div>
    @using (Html.BeginForm("dropDown", "Home", FormMethod.Post))
    {
        @Html.DropDownList("ListItem")

        <button type="submit">Submit</button>
    }

</div>

<p>@ViewBag.SelectedValue</p>

Controller（HomeController.cs）：

        public ActionResult Index()
        {
            bindCombo();
            return View();
        }

        private void bindCombo()
        {
            List<SelectListItem> ObjItem = new List<SelectListItem>()
            {
                new SelectListItem {Text="Select",Value="Select",Selected=true },
                new SelectListItem {Text="ASP.NET",Value="ASP.NET" },
                new SelectListItem {Text="C#",Value="C#"},
                new SelectListItem {Text="MVC",Value="MVC"},
                new SelectListItem {Text="SQL",Value="SQL" },
            };
            ViewBag.ListItem = ObjItem;
        }

        [HttpPost]
        public ActionResult dropDown(string ListItem)
        {
            ViewBag.SelectedValue = ListItem;
            bindCombo();
            return View("index");
        }

Answer 2

就像斯蒂芬·穆克说的那样，你不能发布这份名单。

在index.cshtml文件中更改此行

@Html.DropDownList("ListItem",(List<SelectListItem>)ViewBag.ListItem)

更改控制器中的dropDown方法

public ActionResult dropDown(int ListItem)
{
    List<SelectListItem> ObjItem = new List<SelectListItem>()
    {
        new SelectListItem {Text="Select",Value="0",Selected=true },
        new SelectListItem {Text="ASP.NET",Value="1" },
        new SelectListItem {Text="C#",Value="2"},
        new SelectListItem {Text="MVC",Value="3"},
        new SelectListItem {Text="SQL",Value="4" },
    };

    ViewBag.ListItem = ObjItem;
    ViewBag.SelectedValue = ListItem;

    return View("Index");
}

Answer 3

问题是单击“提交”时无法接收SelectListItem。你的行动将收到idx。此代码将执行您想要的操作：

    List<SelectListItem> ObjItem = new List<SelectListItem>()
    {
  new SelectListItem {Text="Select",Value="0",Selected=true },
  new SelectListItem {Text="ASP.NET",Value="1" },
  new SelectListItem {Text="C#",Value="2"},
  new SelectListItem {Text="MVC",Value="3"},
  new SelectListItem {Text="SQL",Value="4" },
    };

    public ActionResult Index()
    {

        ViewBag.ListItem = ObjItem;

        return View("Index");
    }

    public ActionResult dropDown(string ListItem)
    {
        ViewBag.ListItem = ObjItem;
        ViewBag.SelectedValue = ObjItem.Where(i => i.Value == ListItem).FirstOrDefault().Text;


        return this.View("Index");
    }

MVC5如何从用户写下拉值

3 个答案: