[Zope-dev] Migrating from ZClasses to Python Products

[Jason Spisak]

Brett Carter writes:

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?

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?

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
> 
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