let result = conn.transaction::<i32, Error, _>(|| {
        match diesel::insert_into(orders::dsl::orders)
            .values(NewOrder::empty())
            .returning(orders::dsl::id)
            .get_result(&*conn)
        {
            Ok(inserted_id) => {
                let order_items: Vec<NewOrderItem> = order
                    .0
                    .order_items
                    .iter()
                    .map(|item| {
                        NewOrderItem::new(inserted_id, item.product_code.clone(), item.quantity)
                    })
                    .collect();
                diesel::insert_into(order_items::dsl::order_items)
                    .values(order_items)
                    .execute(&*conn)?;
                Ok(inserted_id)
            }
            Err(e) => Err(Error::NotFound),
        }
    });