codeigniter - gocart session expiration, i want to show alert message -

During the session timeout, I want to show the warning message in gocart that the session has expired. I know that session time will be config file, but how to show a warning message when session expires

< P> To check the expiration of the best session, check the value in the session or not. If the session is not ended ... and instead of warning, to show you the error codeigniter Flashmsg can redirect it to another page.

Example.

  if (! $ -User-> user data ('youritem') {FlashMsg ('error', not in session (session expired) ; Redirected (/ borrow / you / wish);})