[Zope3-Users] z3c.form: Data Manager - getting value via dm.query() instead of dm.get()

[Roger Ineichen]

Hi Hermann
Hi Hermann

> Betreff: Re: AW: AW: AW: [Zope3-Users] z3c.form: Data Manager 
> - getting value via dm.query() instead of dm.get()

[...]

> > Such a search session object could look like:
> >
> > class ISearchSession(ISession):
> >     """Message filter session."""
> >
> >     searchText = zope.schema.TextLine(
> >         title=Search text',
> >         description=u'The search text',
> >         default=u'',
> >         required=False)
> >
> > class SearchSessioon(Session):
> >     _spd = None
> >
> >     @Lazy
> >     def spd(self):
> >         return self.__getitem__('SEARCH_SESSION_KEY')
> >
> >     @apply
> >     def searchText():
> >         def get(self):
> >             return self.spd.get('searchText', u'')
> >         def set(self, searchText):
> >             self.spd['searchText'] = searchText
> >         return property(get, set)
> 
> Is the parent object Session/ISession the one from 
> zope.session? How does it connect to the persistent Session 
> object? And what is "@Lazy"?

Yes,
from zope.session.session import Session

Lazy will cache your method result and return them again
for future access.
See:
from zope.cachedescriptors.property import Lazy

> Yes, that's a possibility, but it would force me to write:
> 
> - An property for every field.
> - A class for every search view.
> 
> All in all that's around ~ 200 lines of code for 5 search 
> forms with appr.
> 5 fields each, compared to appr. 10 lines of code in my solution.

I see

> > I allways use such a session implementation because it 
> abstracts what 
> > you need, uses schema fields, offers built in defaults and 
> works well 
> > with z3c.form.
> 
> Yes, thanks for the code snippet, it's interesting and a 
> clean solution.
> 
> > Note; I'm still not 100% sure if the get() or query() usage in 
> > applyChanges is right or wrong. I hope to find time to deep 
> into that 
> > in the near future.
> >
> > But I think nobody will understand the concept if we 
> implement a form 
> > property for use get or query in applyChanges.
> 
> Yes, that may be true. Hmmm...
> 
> > Hope the session concept works for you till someone 
> agrees/checks the 
> > get/query useage.
> 
> Well, I have two more possibilities until this is sorted out entirely:
> 
> 1) Monkey patch z3c.form.DictionaryField.get() and let it 
> return interfaces.NOVALUE
> 2) Write an register my own data manager to overcome this.

I think a custom data manager is the way to go for you.
Probably a session property handling needs something 
different then a simple dict or a context data manager.

Regards
Roger Ineichen 

> Thanks again for help,
> Best Regards,
> Hermann
> 
> --
> hermann at qwer.tk
> GPG key ID: 299893C7 (on keyservers)
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> 
> 
>