I've committed this change to the trunk and it does have a behavior
change, here's the changelog:
- The "foreign_keys" argument of relation() will now propagate
automatically to the backref in the same way that
primaryjoin and secondaryjoin do. For the extremely
rare use case where the backref of a relation() has
intentionally different "foreign_keys" configured, both sides
now need to be configured explicity (if they do in fact require
this setting, see the next note...).
- ...the only known (and really, really rare) use case where a
different foreign_keys setting was used on the forwards/backwards
side, a composite foreign key that partially points to its own
columns, has been enhanced such that the fk->itself aspect of the
relation won't be used to determine relation direction.
Affect wrote:
>
> Thank you, Bobby and Michael. This seems to work now.
>
> I'm still waiting for your book, Michael. Hope it comes soon!
>
> A.
>
>
> On Jun 12, 5:29 pm, "Michael Bayer" <mike...@zzzcomputing.com> wrote:
>> the "foreign keys" argument as yet is not propagated to the backref (the
>> primaryjoin is), I should look into fixing that, but for now use
>> backref=backref('owner', primaryjoin=pj, foreign_keys=[the foreign
>> keys]).
>>
>>
>>
>> Affect wrote:
>>
>> > Hello:
>>
>> > When I use the foreign_keys argument to the relation function in the
>> > mapper of SA, I get the following error:
>>
>> > ArgumentError: Could not determine relation direction for primaryjoin
>> > condition 'drm_owners.owner_id = drm_contract_royalties.contract_id',
>> > on relation Royalty.owner. Specify the 'foreign_keys' argument to
>> > indicate which columns on the relation are foreign.
>>
>> > This error only shows when the 'backref' argument is specified and not
>> > otherwise! Is this a bug in alchemy or am I missing something?
>>
>> > Here's the mapper conf:
>> > ===================
>> > mapper(Royalty, royalties_table)
>> > mapper(Owner, owners_table,
>> > properties = {
>> > 'works': relation(Work, backref='owner'),
>> > 'royalty': relation(Royalty,
>>
>> > primaryjoin=owners_table.c.owner_id==royalties_table.c.contract_id,
>> > foreign_keys=[royalties_table.c.contract_id],
>> > backref='owner')
>> > })
>>
>> > So, if I remove the 'backref' argument from the call to 'relation',
>> > the relation works, but of course I lose the backref 'owner'.
>>
>> > Thanks!
> >
>
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