public ActionResult Input(OrderDetail model) { model.Product = CatalogBLL.GetProduct(model.ProductID); model.UnitPrice = (model.Quantity * model.Product.UnitPrice) - (model.Quantity * model.Product.UnitPrice * model.Discount / 100); try { CatalogBLL.AddOrderDetail(model); } catch (Exception ex) { OrderDetail detail = CatalogBLL.GetOrderDetail(model.OrderID, model.ProductID); model.Quantity += detail.Quantity; model.UnitPrice += detail.UnitPrice; CatalogBLL.UpdateOrderDetail(model); } return(RedirectToAction("Input", new { id = model.OrderID })); }