ASP.NET MVC PresentationModel綁定到ComboBoxes保持空

Question

您好，我正在學習編程ASP.NET MVC風格。我試圖用我的PresentationModel填充組合框，它不知何故保持空白。

我使用的ASP標籤助手：

視圖（Index.cshtml）

@model Week3_oef2_ITPro.PresentationModel.PMRegistration 

<h2>New Registration</h2> 
<h4>Registration</h4> 
<form asp-controller="Register" asp-action="" method="post"> 
    <table> 
     <tr> 
      <td>Organization</td> 
      <td class="form-group"> 
       <select asp-for="OrgId.Id" asp-items="@Model.Org" class="form-group" /> 
      </td> 
     </tr> 
     <tr><td><input type="submit" /></td></tr> 
    </table> 
</form> 

PresentationModel（PMRegistration.cs）

public class PMRegistration 
{ 
    public Organization OrgId { get; set; } 
    public List<SelectListItem> Org { get; set; } 
} 

模型（Organization.cs）

public class Organization 
{ 
    public int Id { get; set; } 
    public string Name { get; set; } 

} 

數據（其中所有的對象都被初始化）

public class Data 
{ 
    private static List<Session> sessions = new List<Session>(); 
    private static List<Organization> organizations = new List<Organization>(); 
    private static List<Device> devices = new List<Device>(); 

    static Data() 
    { 
     organizations.Add(new Organization() { Id = 1, Name = "Howest" }); 
     organizations.Add(new Organization() { Id = 2, Name = "Vives" }); 
     organizations.Add(new Organization() { Id = 3, Name = "HoGent" }); 
     organizations.Add(new Organization() { Id = 4, Name = "HoLimburg" }); 
     organizations.Add(new Organization() { Id = 4, Name = "De blauwe smurfen" }); 

     devices.Add(new Device() { Id = 1, Name = "Laptop" }); 
     devices.Add(new Device() { Id = 2, Name = "Tablet" }); 
     devices.Add(new Device() { Id = 3, Name = "Apple Watch" }); 
    } 

    public static List<Device> GetDevices() 
    { 
     return devices; 
    } 

    public static List<Organization> GetOrganizations() 
    { 
     return organizations; 
    } 
} 

控制器（RegisterController.cs）

public class RegisterController : Controller 
{ 
    // GET: /<controller>/ 
    [HttpGet] 
    public IActionResult Index() 
    { 
     PMRegistration pm = new PMRegistration(); 
     pm.OrgId = new Organization(); 
     pm.Org = ConverToListItems(Data.GetOrganizations()); 
     return View(pm); 
    } 
    #region methodes 
    private List<SelectListItem> ConverToListItems(List<Organization> data) 
    { 
     List<SelectListItem> items = new List<SelectListItem>(); 
     foreach (var item in data) 
     { 
      items.Add(new SelectListItem() { Text = item.Name, Value = item.Id.ToString() }); 
     } 
     return items; 
    } 
    #endregion 

} 

Answer 1

的SELECT元素你的HTML標記是錯誤的。 SELECT元素需要一個結束標記。

應該

<select asp-for="OrgId.Id" asp-items="@Model.Org" class="form-group"></select>