模型未绑定到 ViewModel ASP.Net MVC

Question

在我的控制器的 GET 编辑功能中，我将 id 作为参数并找到正确的模型。 一切都按原样填充。 我想转身从这个模型生成一个 ViewModel，这样我就可以向它添加更多的字段，但是一旦我用已经填充的模型创建了一个 ViewModel 的实例，一切都保持为空。

public ActionResult Edit(int? id)
    {
        var context = new PrincipalContext(ContextType.Domain);
        var un = UserPrincipal.FindByIdentity(context, User.Identity.Name);
        if (id == null)
        {
            return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
        }

        Ticket ticket = db.Tickets.Find(id);

        var ticketViewModel = new TicketViewModel(ticket);

        if (ticket == null)
        {
            return HttpNotFound();
        }
        List<TicketViewModel> TVM = new List<TicketViewModel>();
        var tl = (from TU in db.Users
                    where TU.sAMAccountName == un.SamAccountName
                    join UD in db.Departments on TU.DepartmentID equals UD.Id
                    select new
                    {
                        TU.Id,
                        TU.sAMAccountName,
                        UD.Name,
                        TU.DepartmentID
                    }).ToList();
        foreach(var listitem in tl)
        {

            ticketViewModel.UserID = listitem.Id;
            //ticketViewModel.DepartmentName = listitem.Name;
            //ticketViewModel.sAMAccountName = listitem.sAMAccountName;
            ticketViewModel.DepartmentID = listitem.DepartmentID;

        }
        ViewBag.CategoryID = new SelectList(db.Categories, "Id", "CategoryName");
        ViewBag.UserID = new SelectList(db.Users, "Id", "CanonicalName", ticket.UserID);
        return View(ticketViewModel);
    }

票务视图模型

public class TicketViewModel
{
    public Ticket Ticket { get; set; }

    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2214:DoNotCallOverridableMethodsInConstructors")]
    public TicketViewModel(Ticket ticket)
    {
        this.NoteHistories = new HashSet<NoteHistory>();

        Ticket = ticket;
    }   
    public int Id { get; set; }
    public string Title { get; set; }
    public int CategoryID { get; set; }
    public string Subcategory { get; set; }
    public string Severity { get; set; }
    public int UserID { get; set; }
    public int DepartmentID { get; set; }
    public string DepartmentName { get; set; }
    public string sAMAccountName { get; set; }
    public string Application { get; set; }
    public int WorkstationID { get; set; }
    public string Notes { get; set; }
    public string Description { get; set; }
    public System.DateTime Created_At { get; set; }
    public System.DateTime Updated_At { get; set; }
    public virtual Category Category { get; set; }
    public virtual Department Department { get; set; }
    public virtual User User { get; set; }
    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly")]
    public virtual ICollection<NoteHistory> NoteHistories { get; set; }

}

票证型号

新的 TicketViewModel(ticket) 之后的 ticketViewModel

Answer 1

当然，它仍然会为空。 您只在TicketViewModel类中设置了三个变量。

在这里，您将创建TicketViewModel的新实例并将TicketModel作为参数传递给构造函数：

var ticketViewModel = new TicketViewModel(ticket);

在构造函数中，您正在设置Ticket变量：

Ticket = ticket;

您在这里设置Id 、 Name 、 aAMAccountName和DepartmentID

        ticketViewModel.UserID = listitem.Id;
        //ticketViewModel.DepartmentName = listitem.Name;
        //ticketViewModel.sAMAccountName = listitem.sAMAccountName;
        ticketViewModel.DepartmentID = listitem.DepartmentID;

就是这样。 你没有设置任何其他东西。

但是我确实注意到上面的内容在foreach ，所以如果列表中有多个项目，它们将被覆盖。