On Tue, Jun 15, 2010 at 9:11 PM, johan de taeye
<johan.de.ta...@gmail.com> wrote:
>
>> You can't do this with a router; as you've noted, the router doesn't
>> have any information about the request in which it is being used.
>>
>> However, you could do it by manually requesting your database
>> connection whenever you use the database. For example:
>>
>> Author.objects.using('otherdb').filter(...)
>>
>> will perform a query that is guaranteed to operate on the 'otherdb',
>> regardless of what the router says.
>
> I was able to get this part working fine. Since most views are based
> on a reuable generic one this was pretty easy to do anyway.
>
> Getting ModelForms (or ModelAdmin) to work with foreign keys is a
> different story: When the form/model is validated, the field value is
> searched in the source table to verify the key exists. This lookup
> uses the _default_manager (see code below), which isn't aware of the
> request any more and always checks on the default database (unless I
> can route it). As a result I always get a validation error on the
> form.
>
> Looks like I need a patched/smarter RelatedField that is aware of the
> database to look in?
You're in somewhat uncharted territory here, so I can't give you a
simple prepared answer. However, you certainly appear to be on the
right track.
It's also possible that you've discovered an edge case bug -- looking
at the code, my gut tells me that the _default_manager call should be
forced onto the same database as model_instance - i.e., the query
should be:
db = router.db_for_read(self.rel.to, instance=model_instance)
qs =
self.re.to._default_manager.using(db).filter(**self.rel.field_name:value})
or similar. I'd need to do more tests to confirm this, though. Feel
free to log a bug if you can reduce this to a test case that
demonstrates that this is indeed a bug.
Yours,
Russ Magee %-)
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