public IActionResult CreateTravelPlan(TravelPlanDTO travelPlanDTO) { bool isCarOnRide = _travelPlanService.IsCarAlreadyOnTheRide(travelPlanDTO.SelectedCarPlates, travelPlanDTO.StartDate, travelPlanDTO.EndDate); if (isCarOnRide) { ModelState.AddModelError("CarOnTheRide", ""); } if (ModelState.IsValid) { TravelPlan travelPlan = _travelPlanService.MapDTOToTravelPlan(travelPlanDTO, _carService); List <TravelPlan> travelPlans = _travelPlanService.GetTravelPlans(); travelPlans.Add(travelPlan); travelPlanDTO.Id = travelPlan.Id; return(RedirectToAction("PickPassengers", travelPlanDTO)); } else { travelPlanDTO.ListOfCars = _carService.Cars.ToList(); return(View(travelPlanDTO)); } }