public ActionResult Create(FleetCarViewModel model)
        {
            try
            {
                if (!ModelState.IsValid)
                {
                    return(View(model));
                }

                // Checks if a car in the fleet already exists:
                if (logic.IsFleetCarExists(model.FleetCar.LicensePlate))
                {
                    ViewBag.ErrorMessage = "Car already exists in the fleet.";
                    return(View(model));
                }
                else
                {
                    // Car in the fleet is OK to insert:
                    logic.InsertFleetCar(model.FleetCar);
                    return(RedirectToAction("Index"));
                }
            }
            catch (Exception)
            {
                ViewBag.ErrorMessage = "An error has occurred. please try again later.";
                return(View(model));
            }
        }
        public ActionResult Edit(FleetCarViewModel model)
        {
            try
            {
                if (!ModelState.IsValid)
                {
                    return(View(model));
                }

                logic.UpdateFleetCar(model.FleetCar);
                return(RedirectToAction("Index"));
            }
            catch (Exception)
            {
                ViewBag.ErrorMessage = "An error has occurred. please try again later.";
                return(View(model));
            }
        }
        /// <summary>
        /// Page displays: A form to edit a car in the fleet.
        /// </summary>
        public ActionResult Edit(string licensePlate)
        {
            try
            {
                FleetCar fleetCar = logic.GetFleetCarByLicensePlate(licensePlate);
                if (fleetCar == null)
                {
                    return(HttpNotFound());
                }

                FleetCarViewModel model = new FleetCarViewModel();
                model.FleetCar = fleetCar;
                return(View(model));
            }
            catch (Exception)
            {
                ViewBag.ErrorMessage = "An error has occurred. please try again later.";
                return(View(new FleetCarViewModel()));
            }
        }