[Zope-dev] Changing and migrating persistence structure

[Hanno Schlichting]

On Sun, Aug 8, 2010 at 2:21 PM, Martin Aspeli <optilude+lists at gmail.com> wrote:
> On 08/08/2010, Jim Fulton <jim at zope.com> wrote:
>> On Thu, Aug 5, 2010 at 2:36 AM, Martin Aspeli <optilude+lists at gmail.com>
>> wrote:
>>> What is the best way to manage this type of migration?
>>
>> Today, it probably makes the most sense to make new classes for the
>> non-persistemnt objects.  You'll then need to write a script to
>> rebuild the data structures.
>
> Okay. So there's no way to get at the data if I take Persistent out of
> the base classes for Records / Record.

There should be some way of doing this with custom __getstate__ and
__setstate__ methods.

It's just tricky to get right and a bit fragile. It's much easier to
write the migration code if both the old and new class are separate
and functioning at the same time.

Hanno