Question

文章视图模型

 public class ArticleViewModel : ViewModelBase
    {

        [Required(ErrorMessage = "Required")]
        public string Title { get; set; }
        [Required(ErrorMessage = "Choose the language")]
        public BELocale Locale { get; set; }
}

public class BELocale : BEEntityBase
    {

        public string OriginalName { get; set; }
        public string FriendlyName { get; set; }
        public string TwoLetterISOName { get; set; }
    }

视图“AddLocaleForArticle”

@model Models.ArticleViewModel

@using (Html.BeginForm("VefifyAddingLocaleForArticle", "Administration"))
{

 @Html.TextBoxFor(m => m.Title, new { disabled = "disabled" })
 @Html.DropDownListFor(m => m.Locale,
                    new SelectList(ViewBag.AvalaibleLocales, "ID", "OriginalName"),   "Select a language"
               )
   @Html.ValidationMessageFor(m => m.Locale)
   <input type="submit" value="Save" />         
}

动作

public ActionResult VefifyAddingLocaleForPhoto(ArticleViewModel article)
        {
            //article.Locale == null for some reason.
             //but article.Title isn't null, it contains the data
            return RedirectToAction("AddingLocaleForPhotoSuccess", "adminka");
        }

为什么article.Locale等于null以及如何修复它？

Answer 1

提交表单时，下拉列表仅将所选值发送给控制器。因此，您不能指望它使用下拉列表填充整个复杂对象，例如BELocale。最好的方法是填充其ID属性，并使用此ID从数据存储中获取剩余的对象。

所以你必须修改你的dropdownlist帮助器，以便它作为第一个参数绑定到locale的id属性：

@Html.DropDownListFor(
    m => m.Locale.ID,
    new SelectList(ViewBag.AvalaibleLocales, "ID", "OriginalName"),   
    "Select a language"
)

现在在相应的控制器操作中，您将获得id：

public ActionResult VefifyAddingLocaleForPhoto(ArticleViewModel article)
{
    // article.Locale.ID will contain the selected locale id
    // so you can use this information to fetch the corresponding BELocale object
    ...
}

Answer 2

您可以在视图模型中填写此类下拉列表

public List<KeyValuePair<int, String>> locale
        {
            get
            {
               return  _localerepo.Findlocals().Select(x => new KeyValuePair<int, string>(x.ID, x.OriginalName)).ToList();
            }
        }

在您的视图中使用此

<%:Html.DropDownListFor(x => x.ID, new SelectList(Model.locale, "key", "value"), "--Select locale--")%>
                <%= Html.ValidationMessageFor(model => model.ID)%>

从asp.net mvc 3中的DropDownList获取选定值

2 个答案: