Re: How to edit dexterity types without needing to know about their behaviors

On Fri, 2014-03-14 at 11:25 +0100, Johannes Raggam wrote:
> On Fri, 2014-03-14 at 02:46 -0700, ajung wrote:
> > ajung wrote
> > > 
> > > johannes raggam wrote
> > >> 
> > >> i'll fix that, probably at the wine and beer sprint. but then you'll
> > >> still always get UTC datetime values instead of localized ones, if you
> > >> get the start/end attributes directly from the context.
> > >> 
> > >>> Consistency-is-king
> > >>> Andreas
> > >> 
> > >> pragmatism is okay.
> > >> johannes
> > 
> > Here are the facts why plone.app.event currently freaks me out.
> > 
> > The source 'start' object is 
> > v = DateTime('2008/09/09 09:00:00 GMT+2') 
> > which translates to 07:00 UTC.
> > 
> > The migration code tries to concert the DateTime instance to a Python
> > datetime instance with UTC timezone and setting the 'timezone' of the event
> > object to 'Etc/GMT+2' using
> > 
> >                     v = v.asdatetime()
> >                     tz = str(v.tzinfo)
> >                     if tz.startswith('GMT'):
> >                         tz = 'Etc/%s' % tz
> >                     new_obj.timezone = tz
> >                     acc = IEventAccessor(new_obj)
> >                     v = v.replace(tzinfo=pytz.timezone('UTC')) 
> >                     setattr(acc, k, v)
> 
> first, are you sure, that you want to use Etc/GMT+2 as timezone? Etc/GMT
> is not GMT, see the answer here:
> http://answers.yahoo.com/question/index?qid=20090707145844AANnghH
> 
> >>> import pytz
> >>> from datetime import datetime
> >>> vie = pytz.timezone('Europe/Vienna')
> >>> etc = pytz.timezone('Etc/GMT+2')
> >>> dt = vie.localize(datetime.now())
> >>> dt
> datetime.datetime(2014, 3, 14, 11, 13, 11, 629280, tzinfo=<DstTzInfo
> 'Europe/Vienna' CET+1:00:00 STD>)
> >>> dt.astimezone(etc)
> datetime.datetime(2014, 3, 14, 8, 13, 11, 629280, tzinfo=<StaticTzInfo
> 'Etc/GMT+2'>)
> 
> then, just set the timezone on the accessor and start and end datetime
> as floating datetimes. if you don't have multiple timezone in the portal
> you are migrating, that shouldn't be a problem.

... and make sure the ObjectModifiedEvent is fired, so that the
data_postprocessing event handler is executed.

please note, these are the steps, recalled from memory. i didn't test
this as i write this email.

> 
> the behavior's setter applies a FAKEZONE, just to be able to compare the
> value against something already stored on the content object without.
> that way, we avoid a "TypeError: can't compare offset-naive and
> offset-aware datetimes", because the widget's value is timezone naive. 
> as i said, i'm going to refactor this....
> 
> then, the data_postprocessing event handler (p.a.event.dx.behaviors,
> line 427) takes the floating-timezone value with it's FAKEZONE, removes
> it and converts that value to UTC, using the timezone attribute from the
> content object.
> 
> i'm going to repeat myself, but i think that was not clear enough.
> 
> 
> 
> > 
> > After the migration the event show up in Plone with 
> > 
> > 09.09.2008 um 07:00 bis 10.09.2008 um 15:00 (Etc/GMT+2 / UTC-200)
> > ^^^^^^^^^^^^^^^^^^^^
> > 
> > Taking the debugger:
> > 
> > >>> ev = app.restrictedTraverse('eteaching/news/tagungen/ilias_2008/')
> > >>> ev.start
> > datetime.datetime(2008, 9, 9, 9, 0,
> > tzinfo=<plone.app.event.dx.behaviors.FakeZone object at 0xa7c1250>)
> > >>> ev = app.restrictedTraverse('eteaching/news/tagungen/ilias_2008/')
> > >>> ev.timezone
> > 'Etc/GMT+2'
> > >>> ev.start
> > datetime.datetime(2008, 9, 9, 9, 0,
> > tzinfo=<plone.app.event.dx.behaviors.FakeZone object at 0xa7c1250>)
> > >>> ev.start.tzinfo 
> > <plone.app.event.dx.behaviors.FakeZone object at 0xa7c1250>
> > >>> ev.start.tzinfo.tzname(ev.start)
> > 'FAKEZONE'
> > 
> > That the hell is a FAKEZONE?
> > 
> > Obviously my code is wrong because it does not change the 'hour' from 9 to 7
> > (because of the two hours offset).
> > 
> > So I changed the code to
> > 
> >     v = v.astimezone(pytz.utc)
> > 
> > In this case the output changed to 
> > 
> > 09.09.2008 um 05:00 ...
> > ^^^^^^^^^^^^^^^^^^^^
> > 
> > ...which is even more weird.
> > 
> > -aj
> > 
> > 
>

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