On Sat, 2009-05-02 at 09:41 -0400, Michael Bayer wrote:
>
> you'd set cascade="all, delete-orphan" on the Purchase.registration
> side (in this case its your backref).
Thanks Mike. So what is the recommended way of creating the attached
item though, or is it supposed to happen automatically from the mapper?
Iain
>
>
> On May 2, 2009, at 1:42 AM, Iain Duncan wrote:
>
> >
> > Hi all, I have a mapper that looks like this:
> >
> > mapper( Registration, registration_table, properties={
> > 'purchase': relation(Purchase,
> > backref=backref('registration', uselist=False),
> > cascade='all' ),
> > })
> >
> > My registration table has a foreign key to purchases, and I want to
> > make
> > sure no registration exists without an associated purchase. I have the
> > referrence backwards like a many-to-one because purchases may also be
> > referred to in other tables ( like memberships ). Maybe this is not a
> > good idea, not sure. Feel free to tell me. Should this perhaps be
> > handled in a separate associating table with primary key with one
> > column
> > primary key constraints on it?
> >
> > But, my immediate problem is that I don't know what the correct way to
> > make sure I create a purchase on creation of a registration. Should
> > I be
> > creating a purchase in the registration constructor? Should I be doing
> > something like:
> >
> > r = Registration( purchase=Purchase() )
> >
> > Or should it work magically if I set up my cascade options
> > differently?
> >
> > Thanks
> > Iain
> >
> >
> >
> > >
>
>
> >
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