// POST api/CheckoutList
        public HttpResponseMessage PostCheckoutList(CheckoutListDto checkoutlist)
        {
            if (ModelState.IsValid)
            {

                foreach (CheckoutItemDto item in checkoutlist.CheckoutItems)
                {
                    var product = tdDb.ShoppingItems.Find(item.ProductId);
                    item.SubTotal = product.Price * item.Quantity;
                    checkoutlist.TotalPrice += item.SubTotal;
                    item.Price = product.Price;
                    item.ProductName = product.Title;
                }

                HttpResponseMessage response = Request.CreateResponse(HttpStatusCode.Created, checkoutlist);
                response.Headers.Location = new Uri(Url.Link("DefaultApi", new { id = checkoutlist.CheckoutListId }));
                return response;
            }
            else
            {
                return Request.CreateErrorResponse(HttpStatusCode.BadRequest, ModelState);
            }
        }
        // PUT api/CheckoutList/5
        public HttpResponseMessage PutCheckoutList(int id, CheckoutListDto checkoutlistDto)
        {
            if (!ModelState.IsValid)
            {
                return Request.CreateErrorResponse(HttpStatusCode.BadRequest, ModelState);
            }

            if (id != checkoutlistDto.CheckoutListId)
            {
                return Request.CreateResponse(HttpStatusCode.BadRequest);
            }

            coDb.Entry(checkoutlistDto).State = EntityState.Modified;

            try
            {
                coDb.SaveChanges();
            }
            catch (DbUpdateConcurrencyException ex)
            {
                return Request.CreateErrorResponse(HttpStatusCode.NotFound, ex);
            }

            return Request.CreateResponse(HttpStatusCode.OK);
        }