无法转换类型'System.Collections.Generic.List< string>'到'System.Web.Mvc.SelectList' [英] Cannot convert type 'System.Collections.Generic.List<string>' to 'System.Web.Mvc.SelectList'

问题描述

我有以下Action方法，其中有一个带字符串列表的viewBag:-

I have the following Action method, which have a viewBag with a list of strings:-

public ActionResult Login(string returnUrl)
        {
            List<string> domains = new List<string>();
    domains.Add("DomainA");

            ViewBag.ReturnUrl = returnUrl;
            ViewBag.Domains = domains;
            return View();
        }

在视图上，我试图构建一个下拉列表，以显示viewBag字符串，如下所示:-

and on the view i am trying to build a drop-down list that shows the viewBag strings as follow:-

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

但是我遇到了以下错误:-

But i got the following error :-

无法将类型'System.Collections.Generic.List'转换为 'System.Web.Mvc.SelectList'

Cannot convert type 'System.Collections.Generic.List' to 'System.Web.Mvc.SelectList'

所以有人能容忍为什么我不能填充st的下拉列表吗? 谢谢

So can anyone adive why i can not populate my DropDown list of a list of stings ? Thanks

推荐答案

因为DropDownList不接受字符串列表.它接受IEnumerable<SelectListItem>.将您的字符串列表转换为该列表是您的责任.不过，这很容易:

Because DropDownList does not accept a list of strings. It accepts IEnumerable<SelectListItem>. It's your responsibility to convert your list of strings into that. This is easy enough though:

domains.Select(m => new SelectListItem { Text = m, Value = m })

然后，您可以将其提供给DropDownList:

Then, you can feed that to DropDownList:

@Html.DropDownList("domains", ((List<string>)ViewBag.domains).Select(m => new SelectListItem { Text = m, Value = m }))

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