public IActionResult GetById(int collectionId, int feedId)
        {
            try
            {
                var currentUserId = int.Parse(User.Identity.Name);

                var feedDto = _feedService.GetById(collectionId, feedId, currentUserId);

                return(Ok(_mapper.Map <FeedModel>(feedDto)));
            }
            catch (ValidationException ex)
            {
                // return error message if there was an exception
                return(BadRequest(new { message = ex.Message }));
            }
        }