On Apr 19, 2011, at 12:57 PM, Kent Bower wrote:
> So, what would you suggest the "right answer" is in this case? In the real
> world scenario we have a potentially good reason to avoid the association
> proxy approach since that involves an additional table which may be unneeded.
>
> Is the best answer just to provide the foreign keys as I did?
it is ! or just have the warning, its not a big deal. id make sure
viewonly=True is set as well.
>
>
> On 4/19/2011 11:47 AM, Michael Bayer wrote:
>> On Apr 19, 2011, at 9:04 AM, Kent wrote:
>>
>>> I'm getting an SAWarning (0.6.4 and also 0.7b5dev) which has a message
>>> that confuses me, so I've duplicated the problem with a script:
>>> ===================================================
>>>
>>> mapper(PostSpotLight, spotlights_table,
>>> properties = {'postkeywords':
>>> relationship(Keyword, secondary=post_keywords,
>>>
>>> primaryjoin=spotlights_table.c.post_id==post_keywords.c.post_id)}
>>> )
>>>
>>> [...]/sqlalchemy-default/lib/sqlalchemy/orm/properties.py:900:
>>> SAWarning: No ForeignKey objects were present in secondary table
>>> 'post_keywords'. Assumed referenced foreign key columns
>>> 'post_keywords.keyword_id', 'post_keywords.post_id' for join condition
>>> 'spotlights.post_id = post_keywords.post_id' on relationship
>>> PostSpotLight.postkeywords
>>> eq_pairs = self._sync_pairs_from_join(self.primaryjoin, True)
>>>
>>> Why is the complaint that there are No ForeignKey objects were present
>>> in secondary table 'post_keywords', when clearly there are?
>> Well this is the message knowing something was wrong but not expressing it
>> in a way that I expected when I wrote it. post_keywords has no foreign keys
>> that refer to the "spotlights" table. if a primaryjoin condition is
>> given, it only cares about foreign keys that express components of the join
>> condition. this used to be an error condition but eventually I figured
>> that things would just "work" if I assumed the cols in post_keywords were
>> FKs, after I saw someone confused by placing a "secondary" table that in
>> fact had no FKs on it.
>>
>>> ***Furthermore, if I pass the relationship this:
>>>
>>> foreign_keys=[post_keywords.c.post_id,post_keywords.c.keyword_id]
>>>
>>> then the warning goes away, but all I've done is specify the very
>>> foreign_keys that already exist.***
>> well in this case you give it some columns, but not what they reference to.
>> So it sees "post_id" and it says, oh, thats the FK that points to
>> spotlights.post_id.
>>
>
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