Value cannot be null. Parameter name: items (in Dropdown List) ASP.NET MVC5

Question

I have problem in my code. I\'m using the registration form which comes with MVC5 , I added a field \"Role\" as a Dropdownlist to assign a role to the user while creating a

Answer 1

Make sure you add the list to the model before returning the view, or you will get this error. Example:

cshtml:

@model DelegatePortal.ViewModels.ImpersonateVendorViewModel


@using (Html.BeginForm("ImpersonateVendor", "Admin", FormMethod.Post))
{
    @Html.DropDownListFor(model => model.Id, new SelectList(Model.Vendors, "Id", "Name"), "Choose a vendor", new { @class = "form-control form-control-sm " })
}

controller:

// GET: /Admin/ImpersonateVendor
    public ActionResult ImpersonateVendor()
    {
        ImpersonateVendorViewModel model = new ImpersonateVendorViewModel();
        var vendors = (from c in db.Vendors
                        select c).ToList();
        model.Vendors = vendors; --> add list here
        return View(model);
    }