public async Task <IHttpActionResult> PostOrder(Order order)
        {
            try
            {
                //Order table
                if (order.OrderID == 0)
                {
                    db.Orders.Add(order);
                }
                else
                {
                    db.Entry(order).State = EntityState.Modified;
                }

                //OrderItems table
                foreach (var item in order.OrderItems)
                {
                    if (item.OrderItemID == 0)
                    {
                        db.OrderItems.Add(item);
                    }
                    else
                    {
                        db.Entry(item).State = EntityState.Modified;
                    }
                }
                // Delete operation for OrderItems
                foreach (var id in order.DeletedOrderItemIDs.Split(',').Where(x => x != ""))
                {
                    OrderItem x = db.OrderItems.Find(Convert.ToInt64(id));
                    db.OrderItems.Remove(x);
                }

                await db.SaveChangesAsync();

                return(Ok());
            }

            catch (Exception e)
            {
                throw e;
            }
        }