public ActionResult Details(int?id)
        {
            if (id == null)
            {
                return(new HttpStatusCodeResult(HttpStatusCode.BadRequest, "id should not be null."));
            }

            var data = repo.GetCustomerById(id.Value);

            if (data != null)
            {
                ViewData.Model = data;
                return(View());
            }
            else
            {
                return(HttpNotFound("Not found customer."));
            }
        }