Hej, chciałem napisać aplikacje "Bibliotekę internetową" w Asp.Net Core MVC.
Mam błąd: "Value cannot be null. (Parameter 'items')". BookViewModel ma relacje jeden do jeden z PublishingHouseViewModel.
<label asp-for="PublishingHouse" class="control-label"></label>
<select asp-for="PublishingHouseId" class="form-control" asp-items="@(new SelectList(@ViewBag.listOfHause,"Id","Name"))"></select>
<span asp-validation-for="PublishingHouseId" class="text-danger"></span>
public class BookViewModel
{
public int Id { get; set; }
[DisplayName("Tytuł")]
public string Title { get; set; }
[ForeignKey("PublishingHouseViewModelId")]
public int PublishingHouseViewModelId { get; set; }
public PublishingHouseViewModel hause { get; set;}
}
public class PublishingHouseViewModel
{
public int Id { get; set; }
[DisplayName("Wydawnictwo")]
public string Name { get; set; }
[DisplayName("Numer telefonu")]
public string PhoneNumber { get; set; }
public virtual BookViewModel Book { get; set; }
}
Proszę o pomoc. Jak mogę to naprawić?