public ActionResult Put(int id, String picture)
        {
            var location = _TripAdvisorContext.Locations.SingleOrDefault(loc => loc.id == id);

            if (location != null)
            {
                location.linkPicture = picture;
                _TripAdvisorContext.SaveChanges();
                return(Ok());
            }
            return(NotFound());
        }
        public ActionResult Put(int id, String content)
        {
            var opinion = _TripAdvisorContext.Opinions.SingleOrDefault(opi => opi.id == id);

            if (opinion != null)
            {
                opinion.Content = content;
                _TripAdvisorContext.SaveChanges();
                return(Ok());
            }
            return(NotFound());
        }