c# - MVC 4 Dropdownlist 通过按钮传递值？

Question

我使用 html 助手创建了一个下拉列表。它能够获取值并绑定(bind)到下拉列表。

如何将选定的下拉值传递给 Controller ​​？

我的看法:

@Html.DropDownList("Language", new SelectList(ViewBag.LangList, "Text", "Value"))
<input type="button" class="btn" title="Filter By Language" 
    value="Filter By Language" onclick="location.href='@Url.Action("SURV_Answer_Result", "SURV_Answer", 
    new { Survey_ID = Model[0].Survey_ID, Language = ViewBag.LangList })'" />

我的 Controller 获取语言并绑定(bind)到下拉列表中:

public ActionResult SURV_GetLanguage(int Survey_ID)
{
  var getlanguagelist = from r in db.SURV_Question_Ext_Model
                        join s in db.SURV_Question_Model on r.Qext_Question_ID equals s.Question_ID
                        where s.Question_Survey_ID == Survey_ID
                        group new { r, s } by r.Qext_Language into grp
                        select grp.FirstOrDefault();

  foreach (var item in getlanguagelist.ToList())
  {
    List<SelectListItem> langResult = new List<SelectListItem>();
    foreach (var item2 in getlanguagelist)
    {
      SelectListItem temp = new SelectListItem();
      temp.Text = item2.r.Qext_Language;
      temp.Value = item2.r.Qext_Language;
      langResult.Add(temp);
    }
    ViewBag.LangList = langResult;
  }
  return View(ViewBag.Langlist) ;
}

我想将语言传递给下面的 Controller :

 public ActionResult SURV_Answer_Result(int Survey_ID, string Language)
 {
   List<AnswerQuestionViewModel> viewmodel = new List<AnswerQuestionViewModel>();
   SURV_GetLanguage(Survey_ID);
  // do whatever i want...
}

Answer 1

View 中的按钮是 type="button"你附上了一个onclick将重定向到 SURV_Answer_Result 的事件路过原文ViewBag属性返回到方法(它不会绑定(bind)到 string Language 因为它是 List<SelectListItem> 。

您需要一个带有 FormMethod.Get 的表格

@using (Html.BeginForm("SURV_GetLanguage", "ControllerName", new { Survey_ID = Model[0].Survey_ID }, FormMethod.Get))
{
  @Html.DropDownList("Language", (Enumerable<SelectListItem>)ViewBag.LangList)
  <input type="submit" ... />
}

注意事项:

1. Survey_ID已作为路由值添加到表单中
2. ViewBag.LangList是Enumerable<SelectListItem>这就是全部DropDownList() 需要 helper 所以没有意义创建另一个 SelectList 的额外开销从中( SelectList 是 Enumerable<SelectListItem> )