public void Post([FromBody] Car car) { if (car.CarType == CarType.Undefined) { throw new ArgumentNullException("Was not chosen \"car type\", please fill out all required fields!"); } else { if (car.Balance < 1) { throw new ArgumentException("Was not entered or entered wrong required field value \"car balance\"! Must be an integer value and greater than 0!"); } } _server.ParkTheCar(car); }