public void InsertOrUpdate(Expert expert)
 {
     if (expert.Id == default(int)) {
         // New entity
         context.Experts.Add(expert);
     } else {
         // Existing entity
         context.Entry(expert).State = EntityState.Modified;
     }
 }
 public ActionResult Create(Expert expert)
 {
     if (ModelState.IsValid) {
         expertRepository.InsertOrUpdate(expert);
         expertRepository.Save();
         return RedirectToAction("Index");
     } else {
         ViewBag.PossibleGroups = groupRepository.All;
         return View();
     }
 }