Re: odd behavior with session variable that contains a list

Makes perfect sense, thanks for that pointer!

On Jul 31, 11:17 am, Alex Gaynor <alex.gay...@xxxxxxxxx> wrote:
> On Fri, Jul 31, 2009 at 1:15 PM, Margie<margierogin...@xxxxxxxxx> wrote:
>
> > I am seeing some behavior with session that I don't understand.  If I
> > have a session variable called recentAddIds that contains a list.  I
> > find that if I append to that list, like this:
>
> >   request.session['recentAddIds'].append(newlySavedId)
>
> > Then when I next receive a GET, I find that request.session
> > ['recentAddIds'] does not contain the appended data (but does contain
> > the data that was there prior to the append).
>
> > If I instead make a copy of the list and put that copy into the
> > session variable, then when I next receive a GET, my session variable
> > does not contain the newly appended data.
>
> >    request.session['recentAddIds'] = [x for x in request.session
> > ['recentAddIds']] + [newlySavedId]
>
> > Can anyone explain why this is and if it is expected behavior?  Is it
> > ok for sesion variables to contain lists or other complex structures,
> > or should they just be simple strings?
>
> > Margie
>
> The reason this is is because of how some of python's magic methods
> work.  doing request.SESSION['key'].append() uses the __getitem__
> method on request.SESSION and calls append on the result, whereas
> doing request.SESSION['key'] = val uses the __setitem__ 
> method.http://docs.djangoproject.com/en/dev/topics/http/sessions/#when-sessi...
> describes how to work with this behavior.
>
> Alex
>
> --
> "I disapprove of what you say, but I will defend to the death your
> right to say it." -- Voltaire
> "The people's good is the highest law." -- Cicero
> "Code can always be simpler than you think, but never as simple as you
> want" -- Me
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