public ActionResult ViewCards(CardInput cardInput) { if (ModelState.IsValid) { CardGenerator cardGenerator = new CardGenerator(cardInput.GeneratingDate, cardInput.NumberOfCards); List <Card> CardList = cardGenerator.GetCardsList(); CardDAO cardDAO = new CardDAO(); if (!cardDAO.ISExsistCardDate(CardList[0].CardNumber)) { GridView gridView = new GridView(); gridView.DataSource = CardList; gridView.DataBind(); Session["CardsListEXCEL"] = gridView; Session["CardsList"] = CardList; return(View(CardList)); } else { ModelState.AddModelError("", "You have already generated cards on this date, so choose aonther date. "); return(View("ShowCards")); } } else { ModelState.AddModelError("", "Card List is not available"); return(View("ShowCards")); } }