public ActionResult Calculate(int creditTypeId, CalculationModel model)
 {
     var creditType = creditTypeService.GetCreditTypeById(creditTypeId);
     if (creditType == null)
     {
         return new HttpNotFoundResult();
     }
     if (ModelState.IsValidField("Amount"))
     {
         try
         {
             model.Result = creditService.CalculateMonthPayment(model.Amount, creditType.ReturnTerm,
                 creditType.Percent);
         }
         catch (Exception)
         {
             model.Result = -1;
         }
     }
     else
     {
         ModelState.Clear();
         ModelState.AddModelError("", "Проверьте коректность данных");
     }
     model.CreditType = creditType;
     return View(model);
 }
 public ActionResult Calculate(int creditTypeId)
 {
     var creditType = creditTypeService.GetCreditTypeById(creditTypeId);
     if (creditType == null)
     {
         return new HttpNotFoundResult();
     }
     var calculateModel = new CalculationModel
     {
         CreditType = creditType
     };
     return View(calculateModel);
 }