public IActionResult OnPost() { if (ModelState.IsValid) { var membership = membershipData.GetMebershipById(Customer.MembershipId); Customer.Membership = membership; if (Customer.Id == 0) { Customer = customerData.Create(Customer); TempData["Message"] = "The Object is created!"; } else { Customer = customerData.Update(Customer); TempData["Message"] = "The Object is updated!"; } customerData.Commit(); return(RedirectToPage("./List")); } var memberships = membershipData.GetMemberships().ToList().Select(p => new { Id = p.Id, Display = p.GetMembershipType() }); Memberships = new SelectList(memberships, "Id", "Display"); return(Page()); }