public IActionResult GetDirectorsOfMovie(int movieId)
        {
            if (!movieRepository.MovieExists(movieId))
            {
                return(NotFound());
            }
            if (!ModelState.IsValid)
            {
                return(BadRequest(ModelState));
            }
            var directors    = directorRepository.GetDirectorsOfMovie(movieId);
            var directorsDTO = new List <DirectorDTO>();

            foreach (var director in directors)
            {
                directorsDTO.Add(new DirectorDTO()
                {
                    Id        = director.Id,
                    FirstName = director.FirstName,
                    LastName  = director.LastName
                });
            }
            return(Ok(directorsDTO));
        }