public HttpResponseMessage update(JObject obj)
        {
            string sessionId = Request.Headers.Authorization.Parameter;

            if (sessionId != null && dbObj.checkSession(ref sessionId))
            {
                Cart cartItem = obj.ToObject <Cart>();
                User user     = UserBLL.getUser(sessionId);
                if (CartBLL.updateCart(user, cartItem))
                {
                    return(Request.CreateResponse(HttpStatusCode.Accepted, UserBLL.getUser(sessionId)));
                }
                else
                {
                    return(Request.CreateResponse(HttpStatusCode.BadRequest, user));
                }
            }
            return(new HttpResponseMessage(HttpStatusCode.Unauthorized));
        }