public async Task UpdateRatingAsync(int filmId) { var film = _unitOfWork.Films.Get(filmId); if (film == null) { throw new FilmNotExistsException("Film not exists!") { FilmId = filmId } } ; film.Rating = _ratingsService.GetFilmsAverageRating(filmId); _unitOfWork.Films.Update(film); await _unitOfWork.SaveAsync(); }