def render_content_on(r)
    r.form do
      r.table do
        r.table_row do
          r.table_data do r.text('From:') end
          r.table_data do r.render(@start_date) end
        end
        r.table_row do
          r.table_data do r.text('To:') end
          r.table_data do r.render(@end_date) end
        end
        r.table_row do
          r.table_data do r.space end
          r.table_data do
            r.submit_button('Previous') do
              previous_dates
            end
            r.submit_button('Next') do
              next_dates
            end
            r.space
            r.submit_button('Go') do
              change_dates
            end
          end
        end
      end
      r.paragraph('Invalid Date Range') unless valid_date_range?
    end
  end