public ActionResult AddParticipant(PromoData promo) { var promoData = _seminarService.GetPromoData(); promo.Positions = promoData.Positions; promo.Seminars = promoData.Seminars; if (promo.Participant?.Position == null) { ModelState.AddModelError("Position", "Укажите должность"); } if (promo.Participant != null && ModelState.IsValid) { bool isTransactionCommitted = _seminarService.AddParticipant(promo.Participant); promo.IsTransactionCommitted = isTransactionCommitted; } return(View("MainPage", promo)); }