Question

MVC方法让我很难理解我如何实际检索数据。

查看

<p>
    @using (Html.BeginForm("About"))
    {
        <span style="margin-top: 1em; float: right;">
            Filter Zone Area @Html.DropDownList("ZoneArea", new SelectListItem[]
            {
            new SelectListItem() { Text = "All", Value = "0" },
            new SelectListItem() { Text = "North", Value = "1" },
            new SelectListItem() { Text = "South", Value = "2"},
            new SelectListItem() { Text = "East", Value = "3" },
            new SelectListItem() { Text = "West", Value = "4" },
            new SelectListItem() { Text = "Central", Value = "5" },},
            new { @onchange = "this.form.submit()" })
        </span>

    }
</p>

控制器

public ActionResult About(School model, FormCollection form)
{
      string strDDLValue = form["ZoneArea"]; 

      var schooList = schGateway.SelectAll();
      schooList = schooList.Where(s => s.Zone_Id == 1);

      if (schooList != null)
      {
          foreach (var school in schooList)
          {
              string[] schLoc = new string[] { school.School_Name, school.Dus_Lat.ToString(), school.Dus_Long.ToString() };
              model.SchooList.Add(schLoc);
          }
      }

      return View(model);
}

当我在下面调试此代码时，它返回空值

string strDDLValue = form["ZoneArea"];

Answer 1

代码中没有问题。我可以通过在视图和控制器中使用完全相同的代码来获取值。区别在于@using（Html.BeginForm（“About”，“Default”）），其中Default是控制器名称。如果我们使用Request.Form [“ZoneArea”]，那么我们可以摆脱FormCollection参数。

Stephen Muecke在评论中给出的解决方案是正确的方法，但在这里我只是说从代码中查看控制器中的值没有错误。

    public ActionResult Index()
    {
        ViewBag.SelectList = GetDict();

        return View();
    }

    public ActionResult About()
    {
        string strDDLValue = Request.Form["ZoneArea"];
        ViewBag.SelectedValue = strDDLValue;
        ViewBag.SelectList = GetDict();
        return View("Index");
    }

    public Dictionary<string,int> GetDict()
    {
        Dictionary<string, int> dict = new Dictionary<string, int>();
        dict.Add("All", 0);
        dict.Add("North", 1);
        dict.Add("South", 2);
        dict.Add("East", 3);
        dict.Add("West", 4);
        dict.Add("Central", 4);

        return dict;
    }

查看：

@using (Html.BeginForm("About","Default"))
{
    <span style="margin-top: 1em; float: right;">
        Filter Zone Area @Html.DropDownList("ZoneArea", new SelectList(ViewBag.SelectList,"value","key",ViewBag.SelectedValue),
        new { @onchange = "this.form.submit()" })
    </span>

}

如何将所选下拉列表值检索到控制器？

1 个答案: