On Oct 3, 2005, at 4:45 AM, Andreas Jung wrote:
Hi,
I am currently thinking about for a new version of PloneCollectorNG
based on Zope 3. The currently implementation uses per-instances
schemas (acquired from a parent object managing the schema). How
would you do that in Zope 3?
It sounds like you want persistent schemas. Although there is some
code in Zope 3 going in that direction, to my knowledge it does not
work right now.
Another question: in Zope 3 we have FieldProperties that
automatically handle setting and getting values. This
implementation stores the values as instance attributes. What would
be the recommended way to store attributes in a RDBMS instead
inside the ZODB? By introducing a new RDBMSFieldProperty that
handles the set/get methods in the same way as the FieldProperty
implementation?
That might be one way of doing it. You'd have to have a unique key
for the object in the RDBMS; maybe an intid would be the way to
look. It might get a little bit tricky, as relying ion intids means
that you start requiring that your object be placed in the ZODB
before you set the attributes. I'd be tempted to look for approaches
already working in the field.
So, alternatively, you might want to look at APE for the RDBMS side
of things, so that your code just puts attributes on the object, and
the storage is responsible for the RDBMS side. A third approach
might be http://codespeak.net/z3/sqlos/.
Gary
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