def index
      @articles = Article.all

      respond_to do |format|
        format.html # index.html.erb
        format.json { render json: @articles }
      end
    end
def index
      @articles = Article.all

      respond_to do |format|
        format.html # index.html.erb
        format.json { render json: @articles }
      end
    end
GET /articles
 GET /articles.json