public IActionResult Quiz(Quiz operation, string action) { if (ModelState.IsValid) { if (operation.CheckAnswer()) { Answer.Instance.correctAnswer++; } Answer.Instance.answers.Add(operation); //Answers.Instance.Add(operation); } else { ModelState.AddModelError("YourAnswer", "недопустимый формат ответа"); return(View(operation)); } if (action == "Next") { return(View(new Quiz())); } return(RedirectToAction("QuizResult")); }