you'd set cascade="all, delete-orphan" on the Purchase.registration
side (in this case its your backref).
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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