所需數據未顯示在html.dropdownlist MVC中

Question

我正在嘗試從模型中填充一些數據以在下拉列表中查看。 為此，我創建了我的模型

模型：

public class NoOfSupportingLanguages
{
    public int LanguageId { get; set; }
    public string LanguageName { get; set; }
}
public class OrganisationModel
{
      public SelectList NoofSupportingLanguages { get; set; }
}

在控制器方面，類似以下內容：

控制器：

public ActionResult Index()
        {
            List<NoOfSupportingLanguages> LanguageOption = new         List<NoOfSupportingLanguages>{
                new NoOfSupportingLanguages{ LanguageId = 1, LanguageName="English" },
                new NoOfSupportingLanguages{ LanguageId = 2, LanguageName="Arabic" },
                new NoOfSupportingLanguages{ LanguageId = 3, LanguageName="French" }
            };
            SelectList languageList = new SelectList(LanguageOption, "LanguageId");
            model.NoofSupportingLanguages = languageList;
            return View(model);
        }

視圖：

 @Html.LabelFor(m => m.NoofSupportingLanguages, "Number of languages to support :")
 @Html.DropDownList("ddlNoOfSupportingLanguages", Model.NoofSupportingLanguages)

但在我的下拉菜單中，我得到的值是：

Web.Models.Organisation.NoOfSupportingLanguages
Web.Models.Organisation.NoOfSupportingLanguages
Web.Models.Organisation.NoOfSupportingLanguages

請提出一些幫助。

提前致謝 ！！

Answer 1

您的代碼有多個錯誤。 首先，要生成SelectList您需要提供2個屬性名稱（用於value屬性和顯示文本），因此需要

SelectList languageList = new SelectList(LanguageOption, "LanguageId", "LanguageName");

接下來，您需要綁定一個屬性，因此您的模型需要包含另一個屬性，例如

public int SelectedLanguage { get; set; }

然后在其

@Html.DropDownListFor(m => m.SelectedLanguage, Model.NoofSupportingLanguages)

因此，當您提交表單時， SelectedLanguage的值將是所選選項的值。

Answer 2

如果要以干凈的MVC方式進行操作，則應更改模型：

public class OrganisationModel
{
      public int SelectedLanguageId { get; set; }
      public List<SelectListItem> NoofSupportingLanguages { get; set; }
}

然后在您的控制器中：

    public ActionResult Index()
    {
        List<SelectListItem> LanguageOption = new List<SelectListItem>{
            new SelectListItem { Value = 1.ToString(), Text = "English" },
            new SelectListItem { Value = 2.ToString(), Text = "Arabic" },
            new SelectListItem { Value = 3.ToString(), Text = "French" }
        };
        //here you can set selected value
        model.SelectedLanguageId = 1;
        model.NoofSupportingLanguages = LanguageOption;
        return View(model);
    }

然后您將可以執行以下操作：

 @Html.LabelFor(m => m.NoofSupportingLanguages, "Number of languages to support :")
 @Html.DropDownListFor(m => m.SelectedLanguageId, Model.NoofSupportingLanguages, "Select Language")

現在，當您發布模式，將自動綁定選擇LanguageId到SelectedLanguageId模型屬性。