public static Response UpdateProduct(int id, string name, int price, int stock, int productTypeId)
        {
            ProductType pt = ProductTypeHandler.GetProductTypeById(productTypeId);

            if (name == "")
            {
                return(new Response(false, "must be filled"));
            }
            else if (stock < 1)
            {
                return(new Response(false, "input must be 1 or more"));
            }
            else if (price < 1000)
            {
                return(new Response(false, "input must be above 1000"));
            }
            else if (price % 1000 != 0)
            {
                return(new Response(false, "input must be multiply of 1000"));
            }
            else if (pt == null)
            {
                return(new Response(false, "product type does not exist"));
            }
            else
            {
                ProductHandler.UpdateProduct(id, name, price, stock, productTypeId);
                return(new Response(true));
            }
        }
        public static ProductType GetProductTypeById(int id)
        {
            ProductType pt = ProductTypeHandler.GetProductTypeById(id);

            return(pt);
        }