[Setup] Re: Migration problem: 'Import Error: No module namedValidators'

[alan runyan]

 Thanks for the hint. Whew.. I got PloneShell running and it's 
> fun indeed. I don't have any experience in using such a nice 
> tool, but I managed to find out what's causing the trouble:

Great.
 
> Several instances of my derived ATContentTypes objects in the 
> root throw the error when a function on them is called. A 
> call of __dict__ reveals that they dont't contain anything. 
> It just returns {}.
> Now, this only happened with some instances. Others, of the 
> same type, are completely fine, both in the root and deeper 
> in the site. It seems that the ones that are broken are the 
> older ones.
> So, this means that they got mangled as soon as I opened the 
> Data.fs with the new Products installed, right?

Empty {} in __dict__ means they could be ghosts. Read more about ZODB.

> So I deleted these objects on the old setup and then tried to 
> run it with the new setup again. Worked! No more Import 
> Errors!! The migration worked, too. But now, of course, there 
> are a lot of other problems to address, because my Plone is 
> somewhat heavily customized ;)

Well - best practices really say you should not rely on Plone Templates.
Atleast make a copy of them and be as protective as possible.  Of course I
don’t know your customizations.  But in building large websites I would say
the best practice is creating two skins: admin skin and retail skin.  Retail
skin should not depend on any plone functionality or if it does; you should
make copies and put them in your skin.

Main reason: Plone's skins change.  Plone is an application/Product and to
be subjected to its UI enhancements in the future is not a great path to
choose, i.e. don’t depend on the application in the future to remain the
same.

Alan

> Thanks a lot for your help!
> 
> andré>
> 
> alan at enfoldsystems.com wrote:
> > so i diagnosed an error like this recently with regards to exif in 
> > ATPhoto or ATImage or whatever.  Its rather difficult - if not 
> > impossible to debug this w/o zopectl.  I would download the 
> PloneShell 
> > from enfoldsystems.com website.
> > 
> > I would read over the 'conversing with zope' article.  
> basically what 
> > you can do is use post-mortem debugging.  zope will throw 
> exception; 
> > you get a python debugger:
> > 
> >   - then you step up the call stack finding where you actually ahve 
> > your 'broken' object orthe object that is causign the problem.
> > 
> >   - poke the object and see what has a reference to Validators
> > 
> > I would *imagine* your problem is something like you have a 
> persistent 
> > Validator in your databse; and validators shouldnt be 
> persistent.  It 
> > would be nice to have objects in ZOpe that not possible to 
> persist ;-) 
> > like
> > 
> > class Validator:
> >   _p_never_persist = True
> > 
> > this would tell the zodb that its impossible to persist a 
> instance of 
> > this type.  and would throw a runtime error in zodb.  but this isnt 
> > the zodb list ;-)
> > 
> > I would imagine its something in your own code base if you have 
> > written anotehr product.
> > 
> > alan
> 
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