the Customer.comments attribute proxies through "comment_association" which is configured as a scalar. this should probably be improved in this particular recipe, but for starting assignment you need to assign a collection first:
c1 = Customer() c1.comments = [] I don't ever use "discriminator_on_association", it's the most awkward and least efficient recipe; it's only there to show an improvement over what Django and Rails do. In practice, I typically advise table_per_assocation; the use case of being able to trace back everything that's "tagged" back to the parents polymorphically is not needed much in practice. On Apr 2, 2013, at 3:45 PM, bruk.habtu <[email protected]> wrote: > I was attempting to implement the example shown in > https://github.com/ContextLogic/sqlalchemy/blob/master/examples/generic_associations/discriminator_on_association.py > > trace: https://gist.github.com/brukhabtu/2294f0873830243845db > my code: https://gist.github.com/brukhabtu/1423c9825252ddcf85a5 > > Customer model inherits CommentMixin. > > Error occurs when appending to the customer's comments > > customer.comments.append(comment) > > > The trace shows that the error happens in associationproxy.py > > return self._scalar_get(getattr(obj, self.target_collection)) > > obj is a Customer model object and self.target_collection is a string with > the value 'comment_association'. > > The attribute exists but is set to None. > > -- > You received this message because you are subscribed to the Google Groups > "sqlalchemy" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/sqlalchemy?hl=en. > For more options, visit https://groups.google.com/groups/opt_out. > > -- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/sqlalchemy?hl=en. For more options, visit https://groups.google.com/groups/opt_out.
