View Model DropDownListForでバインドされていません

Question

ビューモデルによって設定されたドロップダウンリストを作成しようとしていますが、HTTPPOSTで、選択した値を取得しようとしましたが、どんな助けもありがとう。

ビューモデル

public class TransferViewModel 
{ 

    public IEnumerable<User> Users { get; set; } 
    public string SortOrder { get; set; } 
    public SelectList Departments { get; set; } 
    public SelectList Sites { get; set; } 

    public SelectListItem SelectedDepartment { get; set; } 
    public SelectListItem SelectedSite { get; set; } 
    public User SelectedUser { get; set; } 
} 

コントローラ

public ActionResult Sort(TransferViewModel model) 
    { 
     var users = from s in _db.Users select s; 
     var departments = new SelectList(_db.Departments); 
     var sites = new SelectList(_db.Sites); 
     model.Departments = departments; 
     model.Sites = sites; 

     if (model.SelectedDepartment != null) 
     { 
      users = users.Where(s => s.Department.ID == Convert.ToInt32(model.SelectedDepartment)); 
     } 
     else if (model.SelectedSite != null) 
     { 
      users = users.Where(s => s.Site.ID == Convert.ToInt32(model.SelectedSite)); 
     } 

     switch (model.SortOrder) 
     { 
      case "name_desc": 
       users = users.OrderByDescending(s => s.LName); 
       break; 
      case "dept": 
       users = users.OrderBy(s => s.Department.Name); 
       break; 
      case "dept_desc": 
       users = users.OrderByDescending(s => s.Department.Name); 
       break; 
      case "site": 
       users = users.OrderBy(s => s.Site.Name); 
       break; 
      case "site_desc": 
       users = users.OrderByDescending(s => s.Site.Name); 
       break; 
      default: 
       users = users.OrderBy(s => s.LName); 
       break; 
     } 
     model.Users = users; 
     model.Departments = new SelectList(_db.Departments, "ID", "Name", model.SelectedDepartment); 
     model.Sites = new SelectList(_db.Sites,"ID","Name", model.SelectedSite); 
     return View(model); 
    } 

ビュー

@using (Html.BeginForm("Sort", "Transfer", FormMethod.Post)) 
{ 
<p> 
    Display by @Html.DropDownListFor(model => model.SelectedDepartment, Model.Departments, htmlAttributes: new { @class = "form-control"}) 
    Department 
</p> 
<p> 
    or by Location: @Html.DropDownListFor(model => model.SelectedSite, Model.Sites, htmlAttributes: new { @class = "form-control"}) 

</p> 
<p> 
    <input type="submit" value="Search"/> 
</p> 
} 

Answer 1

あなたはを持っている必要があるすべて

public class TransferViewModel 
{ 
    ...................... 
    ...................... 
    public int SelectedDepartment { get; set; } 
    public int SelectedSite { get; set; } 
    ..................... 
    ..................... 
} 

あなたがDataValueMemberとしてバインドされるdropdownlistsためID列を使用するためのアクションで自分自身を語っている：ポストのように、モデル内のプロパティは、ドロップダウンのために選択されたIDはコントローラに戻って掲載されます。

// see that ID argument there that is binding the value which will be posted back 
model.Departments = new SelectList(_db.Departments, "ID", "Name", model.SelectedDepartment); 
model.Sites = new SelectList(_db.Sites,"ID","Name", model.SelectedSite);