public IHttpActionResult Create(Advertisement advertisement)
        {
            if (advertisement == null)
            {
                return(NotFound());
            }

            if (!ModelState.IsValid)
            {
                return(NotFound());
            }
            try
            {
                advertisement.AdvertisementId = Guid.NewGuid().ToString();
                repo.Create(advertisement);
                return(Ok());
            }
            catch (Exception)
            {
                return(InternalServerError());
            }
        }