refactored

app/controllers/admin/base_controller.rb

@@ -21,5 +21,19 @@ module Admin
     def paginate?
       params[:results_per_page].to_i.positive?
     end
+
+    def render_by_format(page, filename)
+      respond_to do |format|
+        format.html do
+          render page
+        end
+        format.csv do
+          raw_csv = @q.result.to_csv
+          send_data raw_csv,
+                    filename: "#{filename}_#{Time.zone.now.to_formatted_s(:number)}.csv",
+                    type: "#{Mime[:csv]}; charset=utf-8"
+        end
+      end
+    end
   end
 end