private ICollection <Genre> GetGenresFromIds(ICollection <int> genreIds) { var pipeline = new Pipeline <Genre>(); pipeline.Register(_filterFactory.MakeGenresForIdsFilter(genreIds)); List <Genre> results = UnitOfWork.Genres.Find(pipeline).ToList(); if (results.Count != genreIds.Count) { throw new EntityNotFoundException(typeof(Genre)); } return(results); }