[HttpGet]
        [Route("api/books/picture/{id}")]
        public HttpResponseMessage GetPicture(int id)
        {
            var data = _repository.Get(id);
            if (data != null)
            {
                byte[] imgData = data.ImageOfBook;
                MemoryStream ms = new MemoryStream(imgData);
                HttpResponseMessage response = new HttpResponseMessage(HttpStatusCode.OK) { Content = new StreamContent(ms) };
                response.Content.Headers.ContentType = new MediaTypeHeaderValue("image/png");
                return response;
            }
            return Request.CreateResponse(HttpStatusCode.NotFound, "Not Found");
        }