[Zope] Re: Error importing objects 2.8 > 2.7

[Tres Seaver]

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Dieter Maurer wrote:
> Andreas Jung wrote at 2006-1-28 09:04 +0100:
> 
>>
>>--On 27. Januar 2006 22:32:07 +0100 Dieter Maurer <dieter at handshake.de> 
>>wrote:
>>
>>
>>>Andreas Jung wrote at 2006-1-27 07:04 +0100:
>>>
>>>>...
>>>>Importing stuff from a new Zope version into an older Zope version was
>>>>_never_ a supported feature. Only import between _identical_ versions.
>>>>Anything else makes little sense and is unsupported.
>>>
>>>Of course, you might be happy when you can import into a newer Zope
>>>version from an older one. At least, that makes some sense :-)
>>>
>>
>>Of course we would be happy if we could do that. But export/import was 
>>never designed to deal with migration issue.
> 
> 
> Export/import is essentially what the ZODB does all the time.
> 
> If export/import does not work between given Zope versions, it is quite
> likely that the same Zope versions will have difficulties with
> storages exchange -- and this *IS* a migration issue, Zope should
> be concerned with (and not the applications).
> 
> If it does, export/import will simply follow (in most cases).

Agreed:  for "forward-migration" of data, Zope has historically tried
*very* hard to ensure that objects which had been created under an older
version of Zope would be unpicklable under a newer version:  we have
treated the exceptions as serious bugs (where the problem was not due to
third-party application code, anyway).

However, the original poster wants to be able to import a .zexp file
exported from a *newer* version of Zope into an *older* version.
Keeping that path open has *not* been a goal for Zope, and so the OP
needs to find another way to solve his problem.


Tres.
- --
===================================================================
Tres Seaver          +1 202-558-7113          tseaver at palladion.com
Palladion Software   "Excellence by Design"    http://palladion.com
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