ASP.NET MVC DropDownListFor傳遞類型控制器

Question

如何從DropDownListFor傳遞的SelectedItem到public ActionResult Index(IndexViewModel indexViewModel)。提交後，我有emp=null。 我應該代替地方"Number"在IndexViewModel.ListOfEmployee = new SelectList(ListOfEmployee, "Number", "Name");

控制器：

public class HomeController : Controller 
{ 
    // 
    // GET: /Home/ 

    public ActionResult Index() 
    { 
     List<Employee> ListOfEmployee = new List<Employee>(); 
     ListOfEmployee.Add(new Employee { Name = "Jhon", Number = 1 }); 
     IndexViewModel IndexViewModel = new IndexViewModel(); 
     IndexViewModel.ListOfEmployee = new SelectList(ListOfEmployee, "Number", "Name"); 

     return View(IndexViewModel); 
    } 
    [HttpPost] 
    public ActionResult Index(IndexViewModel indexViewModel) 
    { 
     return View(); 
    } 

} 

查看：

@model MvcApplication3.Models.IndexViewModel 
@{ 
    ViewBag.Title = "Index"; 
} 

<h2>Index</h2> 
@using(@Html.BeginForm()) 
{ 
@Html.DropDownListFor(model=>model.emp ,Model.ListOfEmployee) 

    <input type="submit" /> 
} 

型號：

public class IndexViewModel 
{ 
    public SelectList ListOfEmployee { get; set; } 

    public Employee emp { get; set; } 
}