public IEnumerable <Article> GetByCategoryId(int categoryId) { List <Article> articles = new List <Article>(); articles.AddRange(_articleData.GetByCategoryId(categoryId)); foreach (Article article in articles) { article.ArticleRefs = _articleRefData.GetById(article.Id); article.CategoryRefs = _categoryRefsData.GetById(article.Id); } return(articles); }