public IActionResult Checkout(Order order)
        {
            if (order?.Items?.Any() != true)
            {
                return(RedirectToAction("GetAll"));
            }
            var items          = catalogueService.GetByIds(order.Items.Select(item => item.Id));
            var user           = (order.User?.Id).HasValue ? userService.GetById(order.User.Id) : null;
            var orderViewModel = new OrderViewModel()
            {
                Items = items
                        .Join(order.Items, i => i.Id, i => i.Id, (item, order) => new OrderItemViewModel(item, order.Count))
                        .ToList(),
                User = user
            };

            return(View("../Order/Order", orderViewModel));
        }