David Pratt wrote:
There seems to be enough of a difference between Z2 and Z3 undo to have an effect on a backend like PGStorage from working on Z3. I believe the objective in the storage api is that it should not matter to the backend whether you are connected to Z2 or Z3. Can someone more familiar with the history of undo in z2 and z3 explain the current situation?

Undo has a fairly complicated API, and I can easily believe that Z2 and
Z3 call that API in very different ways.

BTW, I strongly discourage use of Undo except in emergencies.
Sadly, except when undoing the last (non-undo) transactions in
a database can lead to inconsistency.  Undo should be used with
caution and should generally not be exposed to non-expert users.

In Z3, before bringing up the contents view, there is a check of the undo transactions for the principal. It uses z3's undo manager to getPrincipalTransactions which eventually results in a lookup in the undoLog in the external storage where it dies. Just a brief look at the undo code in z3 gives me the feeling the format

Format of what?

> between z2 and z3 may be
incompatible which may be the problem.

The relevant portion of the traceback I receive is this:

File "/usr/local/zope3/z3trunk/src/zope/tales/expressions.py", line 199, in _eval
    return ob()
File "/usr/local/zope3/z3trunk/src/zope/app/publisher/browser/viewmeta.py", line 419, in __call__
    return meth(*a, **k)
File "/usr/local/zope3/z3trunk/src/zope/app/undo/browser.py", line 33, in principalLastTransactionIsUndo
File "/usr/local/zope3/z3trunk/src/zope/app/undo/__init__.py", line 108, in getPrincipalTransactions
    return self._getUndoInfo(context, principal, first, last)
File "/usr/local/zope3/z3trunk/src/zope/app/undo/__init__.py", line 129, in _getUndoInfo
    entries = self.__db.undoInfo(first, last, specification)
File "/usr/local/zope3/z3trunk/src/ZODB/UndoLogCompatible.py", line 37, in undoInfo
    return self.undoLog(first, last, filter)
File "/usr/local/zope3/z3trunk/src/ZODB/PGStorage/pgstorage.py", line 478, in undoLog

You should report this to Shane.

It's possible that there is a bug in PGStorage in handling
extension data.  I can easily believe that Z2 doesn't use extension
data and perhaps z3 does.


Jim Fulton           mailto:[EMAIL PROTECTED]       Python Powered!
CTO                  (540) 361-1714            http://www.python.org
Zope Corporation     http://www.zope.com       http://www.zope.org
For more information about ZODB, see the ZODB Wiki:

ZODB-Dev mailing list  -  ZODB-Dev@zope.org

Reply via email to