private void PrepareSummary() { var rentalItems = new List <RentalItemModel>(); rentalItems.AddRange(SelectedProps); if (SelectedBooth != null) { rentalItems.Add(SelectedBooth); } if (SelectedBackground != null) { rentalItems.Add(SelectedBackground); } OrderPreview = _orderFacade.PrepareOrderAsync(rentalItems, Products.Where(t => SelectedProductIds.Contains(t.Id)).ToList(), OrderBasicInfo).Result; }