public void InsertOrUpdate(Address address)
 {
     if (address.Id == default(int)) {
         // New entity
         context.Addresses.Add(address);
     } else {
         // Existing entity
         context.Entry(address).State = EntityState.Modified;
     }
 }
 public ActionResult Create(Address address)
 {
     if (ModelState.IsValid) {
         addressRepository.InsertOrUpdate(address);
         addressRepository.Save();
         return RedirectToAction("Index");
     } else {
         ViewBag.PossiblePeople = personRepository.All;
         return View();
     }
 }