自动递增编号MVC5

Question

I am new to MVC and i'm trying to create an auto incrementing id upon using CRUD create. I've created my model with id :

    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int BookingId { get; set; }

and my controller:

 public ActionResult Create()
    {
        ViewBag.OpticianId = new SelectList(db.Opticans, "OpticianId", "UserId");
        ViewBag.PatientId = new SelectList(db.Patients, "PatientId", "HCN");
        ViewBag.PracticeId = new SelectList(db.Practices, "PracticeId", "PracticeName");
        ViewBag.AppointmentTime = new SelectList(db.Times, "AppointmentTime", "AppointmentTime");
        return View();
    }

    [HttpPost]
    [ValidateAntiForgeryToken]
    public ActionResult Create([Bind(Include = "BookingId,Date,PracticeId,AppointmentTime,OpticianId,PatientId")] Booking booking)
    {
        if (ModelState.IsValid)
        {
            db.Bookings.Add(booking);
            db.SaveChanges();
            return RedirectToAction("Index");

            }

        ViewBag.OpticianId = new SelectList(db.Opticans, "OpticianId", "UserId", booking.OpticianId);
        ViewBag.PatientId = new SelectList(db.Patients, "PatientId", "HCN", booking.PatientId);
        ViewBag.PracticeId = new SelectList(db.Practices, "PracticeId", "PracticeName", booking.PracticeId);
        ViewBag.AppointmentTime = new SelectList(db.Times, "AppointmentTime", "AppointmentTime", booking.AppointmentTime);
        return View(booking);
    }

I have removed the Booking id from the view but when I try to add a new booking I am getting the following exception:

'System.Data.Entity.Infrastructure.DbUpdateException'

StackTrace " at System.Data.Entity.Internal.InternalContext.SaveChanges()\\r\\n at System.Data.Entity.Internal.LazyInternalContext.SaveChanges()\\r\\n at System.Data.Entity.DbContext.SaveChanges()\\r\\n at CSCOpticians.Controllers.BookingsController.Create(Booking booking) in c:\\Users\\User\\Documents\\Visual Studio 2013\\Projects\\CSCOpticians\\CSCOpticians\\Controllers\\BookingsController.cs:line 89\\r\\n at lambda_method(Closure , ControllerBase , Object[] )\\r\\n
at System.Web.Mvc.ActionMethodDispatcher.Execute(ControllerBase controller, Object[] parameters)\\r\\n at System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary 2 parameters)\\r\\n at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary 2 parameters)\\r\\n at System.Web.Mvc.Async.AsyncControllerActionInvoker.ActionInvocation.InvokeSynchronousActionMethod()\\r\\n at System.Web.Mvc.Async.AsyncControllerActionInvoker.b__39(IAsyncResult asyncResult, ActionInvocation innerInvokeState)\\r\\n at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResult 2.CallEndDelegate(IAsyncResult asyncResult)\\r\\n at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResultBase 1.End()\\r\\n at System.Web.Mvc.Async.AsyncResultWrapper.End[TResult](IAsyncResult asyncResult, Object tag)\\r\\n at System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethod(IAsyncResult asyncResult)\\ r\\n at System.Web.Mvc.Async.AsyncControllerActionInvoker.AsyncInvocationWithFilters.b__3d()\\r\\n at System.Web.Mvc.Async.AsyncControllerActionInvoker.AsyncInvocationWithFilters.<>c__DisplayClass46.b__3f()" string

Answer 1

您已在视图中删除BookingID还要切除BookingID在绑定

public ActionResult Create([Bind(Include = "Date,PracticeId,AppointmentTime,OpticianId,PatientId")] Booking booking)