On Tuesday 23 September 2008 16:06:07 Michael Bayer wrote:
> On Sep 23, 2008, at 7:58 AM, [EMAIL PROTECTED] wrote:
> > hi
> > i cant get how to configure cascades over many-to-many relations.
> > in my case these are implicit m2m (via secondary-table), being
> > treated as either versioned one2many, or versioned many2one.
> >
> > lets say there is versioned A having many versioned Bs.
> > (' and " denote version number):
> > A1' has B1 which has versions:
> > A1'.bs = [B1', B2']
> > (another timestamp)
> > A1'.bs = [B1", B2']
> > A2 has versions which keep same B2, one has also B3:
> > A2'.bs = [B2']
> > (another timestamp)
> > A2".bs = [B2', B3']
> >
> > deleting A1' should delete B1' and B1"
> > deleting A2' should not delete B2'; only deleting all A2' and A2"
> > and A1' should delete B2'.
> > is this "all,delete-orphan" given to the A.relation(B) ?
> > or only "delete-orphan"?
> > how about backrefs (if any)
>
> delete-orphan pretty much needs delete to work correctly. but for
> the many-to-many use case, I'm not sure if SQLA does "the right
> thing" and cross references every relationship - these cascades
> were designed more for the o2m direction (I think Hibernate
> supports them only for o2m relations). I'd work up some simple
> test cases to see what it has to say in this regard (it would have
> to actively load in other objects to see if an object is truly an
> "orphan", for example. not sure if its going to try that).
so far i've used "all" and it seems to work for one single owner, but
i havent really tried the multiple case. the whole thing seems to me
like a splitted reference-counting mechanism, one side being weakref,
other not.
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"sqlalchemy" group.
To post to this group, send email to sqlalchemy@googlegroups.com
To unsubscribe from this group, send email to [EMAIL PROTECTED]
For more options, visit this group at
http://groups.google.com/group/sqlalchemy?hl=en
-~----------~----~----~----~------~----~------~--~---
