public string GiveAwayCar(int CarId, int NewCarUserId) { if (CarId <= 0 || NewCarUserId <= 0) { return "Error"; } var GiveAwayCar = uOW.CarRepo.Get(s => s.Id == CarId).FirstOrDefault(); if (GiveAwayCar == null) { return "Error"; } uOW.CarRepo.SetStateModified(GiveAwayCar); GiveAwayCar.UserId = NewCarUserId; GiveAwayCar.isMain = false; uOW.Save(); return "Success"; }