[Zope3-Users] zodb and object updating

[Chris Withers]

Isn't this what the "generations" code is for?

cheers,

Chris

Pete Taylor wrote:
> Hi all,
> I've run into an interesting issue.  I've been building an application
> in zope3 over the last few months to meet a business need where I
> work.  Basically just capturing a lot of data about prospective
> insurance agencies, creating applications for them, pdfing them
> (reportlab rocks), and emailing the responsible parties, archiving the
> applications, etc.
> 
> the issue is though that as the business community comes back to me
> with changes, there are cases where the object design itself needs to
> be modified.  Things that were Textline's need to be Lists, etc, as
> they determine that they would like to capture extra values for
> similar data, and what have you.
> 
> obviously it's not a problem for just modifying the objects for all of
> them going forward, but for all old data and archived applications, I
> need to update the old objects to fit the new interfaces.  as an
> example, the original design spec only allowed for one agency owner. 
> it was a Textline.  they then asked to be able to have multiple
> owners, in the case of a partnership.  I would, of course, then change
> "owner" to "owners" and make it a List, and modify the relevant bits
> in the rest of the code.  but all the old applications will just have
> a single "owner" Textline as that particular attribute for the class. 
> I need to be able to go through the old applications, find all
> instances of "owner", create "owners" in the stored object, and make
> the original "owner" a single element in the new list.
> 
> my issue is how to do this offline in the zodb.  I've read through the
> posts I can find on manipulating the zodb, but I haven't really
> "gotten" it, and a lot of what i can find is zope2 stuff...  my
> knowledge of the zodb isn't extensive, so the zope2 info may still be
> good?
> 
> if anyone has links or recommendations on where to look to start doing
> this kind of thing, that would be excellent, as would any advice on
> do's and don't's.  as this application lives in our environment,
> changes to the design will inevitably create this issue time and
> again, so I'd like to know how to confront changes like this in a
> workable way.
> 
> Thanks!
> 
> --
> "All guilt is relative, loyalty counts, and never let your conscience
> be your guide."
>   - Lucas Buck, American Gothic
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