Thursday, February 28, 2013

Re: Possible bug with Form Wizard and condition_dict?

When "starting" the wizard, the "current" step is the *first* step.
The "first" step is the first in the list of *currently enabled* steps.
The list of "currently enabled" steps is constructed by checking each step wrt. condition_dict.

In other words; obtaining the current step implicitly runs the callables in condition_dict, so doing that from one of the callables leads to infinite recursion.

Personally, I'm not sure whether this should be considered a bug; the wizard implementation could probably be reorganised to only check condition_dict until a "first" step was found; but the resulting behaviour would be somewhat difficult to describe; accessing wizard.steps.current from the callables in condition_dict would still be unsafe from those callables checked in order to find the "first"; i.e. in the general case, the problem cannot be solved.  On the other hand, the current behaviour/limitation does not appear to be documented...

I have a hard time imagining a scenario where checking the current step makes sense for determining what steps are available --- the step being checked for would clearly not be visited on every run-through of the wizard, but if that step is enabled based on some different conditional, reusing that might make more sense?  (... or at least work with the current wizard.)

A possible workaround may be to store some data on an instance member on the wizard object --- or on the wizard objects storage --- in process_step(), and then check that in the callable.

On Friday, 5 October 2012 17:16:02 UTC+2, Scott Woodall wrote:
I searched the bug tracker and the django users with no results, so is what I'm seeing a bug?

I have a form wizard that is using a callable within condition_dict. If I try to access "wizard.steps.current" inside the callable, I get the following error:

"maximum recursion depth exceeded in __instancecheck__"
Exception Location: /System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/ in _reconstruct, line 307

Just trying to figure out if I should file a bug report or I'm doing something wrong?

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