On Sun, 2009-05-03 at 09:43 -0400, Michael Bayer wrote:
>
>
> On May 2, 2009, at 8:16 PM, Iain Duncan wrote:
>
> >
> > 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?
>
>
> you can say p.registration = r, or Purchase(registration=r), the
> cascade option would enforce the constraint at flush time.
Ah, so that is the reverse of what I was thinking. You see, the form's
job is to create a registration. So is it equally fine to go the other
way?
r = Registration( purchase=Purchase() )
or even better ( i hope? )
class Registration(object):
def __init__(self, **kwargs):
self.purchase = Purchase()
for k,v in kwargs.items(): setattr(self,k,v)
?
thanks Mike
Iain
>
>
> >
> >
> > 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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