[Zope-dev] Migrating from ZClasses to Python Products

[Ender]

Jason Spisak wrote:
> 
> The only problem I am dealing with is size.
> What kind of a transaction will that be?
> Huge, no doubt.
> 
> I would run out of space to buffer it.  Does Zope do subtransactions now,
> or is that still just the ZCatalog?

zope has done subtransactions for a while, i'm not sure if this predates
zcatalog or not ( i assume'd it does).

just call get_transaction.commit(1) to save work. and call 
get_tranaction.commit() when you're done. i'm in the process of writing
an advanced transaction how-to which will hopefully give some more
enlightenment on this process, but i've been busy with work so i don't
expect to have it public for another week.

> Also, I am running on stock RH6.2 linux and to double my ZODB puts me near
> the 2 gig file limit.  Not as much of a concern as a pain in my neck.  Is
> it faster to modify my installation to allow > 2GB or create from
> xml/export?

you could create the python product instances in a mounted db.

Kapil

> Jason
> >
> > It should be Really Easy (TM) to write an external method that grabs
> > the data from your zclasses, and then creates a new instance of your
> > python object with the zclass data.  It's just a big for loop.
> > -Brett
> >
> > >>>>> "Jason" == Jason Spisak <444@hiretechs.com> writes:
> >
> >     Jason> Shane:
> >     >> Jason Spisak wrote:
> >     >> > > > And now the big question...
> >     >> > > >
> >     >> > > > How do you migrate and existing application from ZClasses to Python
> >     >> > > > products?  I've got about 50,000 objects.  Can it be done or am I stuck
> >     >> > > > with ZClasses?
> >     >> > >
> >     >> > > Andy McKay writes:
> >     >> > >
> >     >> > > Well the number of objects doesnt really matter, but migrating it from
> >     >> > > ZClass to Python - Ive never heard of that happening. It would be a cool
> >     >> > > project though.
> >     >>
> >     >> The hard part (which probably isn't very hard after all :-) ) is writing
> >     >> the product that performs the same function as the ZClass. Once that's
> >     >> done, a fifteen-line external method (that doesn't use any special
> >     >> voodoo) can convert all instances.
> >     >>
> >     >> Shane
> >
> >
> >     Jason> Perhaps what I should do is just get the data out, and create new instances
> >     Jason> all via an external method.  The migration isn't really a 1 for 1
> >     Jason> situation. I am trying to address shortcomings like not having a
> >     Jason> "dictionary" type property in Zope properties, etc.. So the implementation
> >     Jason> will be different anyway.  I guess an export to XML gives me all the data
> >     Jason> in the objects, right?  Then I could use that as a map to construct new
> >     Jason> instances in a different implementation.
> >
> >
> >     Jason> Thanks for all the answers,
> >
> >     Jason> Jason
> >
> >     Jason> _______________________________________________
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> >
> 
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