[ZODB-Dev] historicalRevision for subobjects

[Christian Heimes]

Hey :)

I need some guidance from ZODB gurus.

Christian Theune and me have implemented a diffed history feature for 
Archetypes based content types. It's part of ATContentTypes and is meant 
to help reviewers to see the differences between different revisions of 
an object. The code is using the method OFS.History.historicalRevision + 
db().oldstate() to iterate over the ZODB revisions of the object.

The code was working very well because we were using AttributeStorage. 
AS stores the data of Archetype fields as a simple attribute on the 
object. For security and performance reasons I have implemented 
annotation storage that is using Zope3 style attribute annotations to 
store the data in an OOBTree attached to the object. With 
AnnotationStorage the history isn't working any more because 
historicalRevision() returns only an older version of the object but 
*not* older versions of its subobjects like the btree. Even trying to 
get the different revisions of the oobtree didn't help. The symptoms 
were the same. I assume I have to get the revisions of the btree bucket 
or choose a different path.

I had the idea of getting a snapshot of the entire ZODB for a given 
transaction serial number but I don't know how to get it. Is this possible?

The code for the feature including some tries is in:

http://svn.plone.org/collective/ATContentTypes/branches/tiran-ann-history-fix/lib/historyaware.py

Christian (Tiran)