[albatross-users] SessionAppContext handling session timeout / deleting.

[Greg Hamilton]

On Tue, Jun 05, 2007 at 12:12:24AM +1000, Andrew McNamara wrote:
  | >I'm using SessionAppContext/SimpleSessionApp for server side  sessions.
  | >After a server session times out and I receive a subsequent request from a
  | >client  (which had a session) as a result a SessionExpired exception is
  | >raised (quite correctly  since it timed out) which I guess I have to catch
  | >at app.run(Request()).
  | >
  | >What is the right way to delete the old session and return a selected
  | >template page?  I notice your FAQ has an entry describing how to delete a
  | >session  when I have a handle to the context.  But in this case I don't
  | >have a handle to the  context because of where I am handling the exception
  | >and presumably because if it is  expired it never got instantiated for
  | >that request...
  | >
  | >Feel free to point me to relevant documentation (I did look but  nothing
  | >jumped out at me that seemed appropriate) but I am new to Albatross and
  | >may have  missed it.
  | 
  | Hmmm, tricky. There's no need to delete the session, since it's already
  | gone: I suspect what you should do is replace the default exception page
  | with a friendlier version for this specific exception. 
  | 
  | The Application classes call their handle_exception() method when the run
  | method raises an exception - you could subclass the Application class
  | you've chosen, and add your own handle_exception method that presents
  | your chosen template.
  | 
  | Have a look at Application.handle_exception() in albatross/app.py -
  | you'll basically want to do something very similar to what's there.
  | 
  | If you think overloading the albatross method is against the rules,
  | don't worry - this is the way Albatross is intended to be used (which
  | is why all manner of "internal" methods are documented).
  | 

I've been bitten by this before. The default handle_exception removes
the session for any unhandled exception. The browser still has a cookie
identifying the removed session. All subsequent requests result in a
SessionExpired exception.

I work around this by removing the session and creating a new session
before I run the template which reports the error.

Something like this ...

    def handle_exception(self, ctx, req):
        ctx.remove_session()
        ctx.new_session()
        ctx.reset_content()
        self.save_session(ctx)
        ctx.run_template('unhandled_exception.html')
        ctx.flush_content()

I'm sure Andrew will be appalled by this and suggest a far superior
solution.

Greg Hamilton
Object Craft