// POST api/Product
        public HttpResponseMessage PostProduct(Product product)
        {
            if (ModelState.IsValid)
            {
                product.rowguid = Guid.NewGuid();
                product.ModifiedDate = DateTime.UtcNow;

                db.Products.Add(product);
                db.SaveChanges();

                HttpResponseMessage response = Request.CreateResponse(HttpStatusCode.Created, product);
                response.Headers.Location = new Uri(Url.Link("DefaultApi", new { id = product.ProductID }));
                return response;
            }
            else
            {
                return Request.CreateErrorResponse(HttpStatusCode.BadRequest, ModelState);
            }
        }
        // PUT api/Product/5
        public HttpResponseMessage PutProduct(int id, Product product)
        {
            if (!ModelState.IsValid)
            {
                return Request.CreateErrorResponse(HttpStatusCode.BadRequest, ModelState);
            }

            if (id != product.ProductID)
            {
                return Request.CreateResponse(HttpStatusCode.BadRequest);
            }

            product.ModifiedDate = DateTime.UtcNow;

            db.Entry(product).State = EntityState.Modified;

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

            return Request.CreateResponse(HttpStatusCode.OK);
        }