[Zope-dev] Help: __getstate__ overriding

[Dieter Maurer]

Syver Enstad wrote at 2004-5-28 12:41 +0200:
>I have a Persistent derived class where I want to upgrade from using a
>PersistentList to a BTrees.IOBTree.IOBTree.
>
>_articleList is the old Persistent list
>_oidsToArticles is the new IOBTree.
>
>    def __setstate__(self, state):
>        articleList = state.get('_articleList')
>        if articleList:
>            oidsToArticles = self.makeBTree()
>            for each in articleList:
>                oidsToArticles[each.oid()] = each
>            del state['_articleList']
>            state['_oidsToArticles'] = oidsToArticles
>        Persistent.__setstate__(self, state)
>
>This seems to work fine, and I am adding more objects to
>_oidsToArticles. The problem is that when I commit the transaction,
>nothing is saved. I have tested the same code without __setstate__ and
>then it saves just fine. What hoops does one have to jump through to
>upgrade the state of a ZODB object?

This does not work as changes made in "__setstate__" are not
explicitly persisted. Whether or not they become persistent
depends on whether the object is changed again outside "__setstate__".

Use an explicit conversion script instead...

-- 
Dieter