Hi Simon,
Thanks for the post. I just tried this and ForeignObject requires one of
the 2 columns being referred to be unique. But thats an interesting object!
On Saturday, June 18, 2016 at 8:34:31 PM UTC+5:30, Simon Charette wrote:
>
> Hi Ram,
>
> I don't have a complete solution for you but I suggest you take a look at
> the
> django.db.models.fields.related.ForeignObject class.
>
> If I'm not mistaken it should allow you to define multi-column
> relationships
> on both your Article and PublisherMediumBilling models and refer to them
> using
> the `select_related()` and `prefetch_related()``API while the later uses
> Python
> to perform in-memory JOINs.
>
> class Article(models.Model):
> publisher = ForeignKey(Publisher, related_name='articles')
> medium = ForeignKey(Medium)
> billing = ForeignObject(
> 'PublisherMediumBilling', from_fields=['publisher', 'medium'],
> to_fields=['publisher', 'medium']
> )
>
> publisher.articles.select_related('billing')
>
> Cheers,
> Simon
>
> Le samedi 18 juin 2016 07:09:03 UTC-4, Ram Jayaraman a écrit :
>>
>> I apologize if this is an old question, I did search SO/google for a good
>> few hours.
>>
>> I have the following models.
>>
>> Publisher()
>> name = CharField()
>>
>> Medium()
>> name = CharField()
>>
>> Article()
>> publisher = ForeignKey(Publisher, related_name="articles")
>> medium = ForeignKey(Medium, related_name="articles")
>> text = TextField()
>>
>> PublisherMediumBilling()
>> publisher = ForeignKey(Publisher()
>> medium = ForeignKey(Article)
>> lots_of_other_columns
>> ...
>> class Meta:
>> unique_together = ['publisher', 'medium']
>>
>>
>>
>> I am looking to query all Article from a given publisher, and also fetch
>> the related PublisherMediumBilling joining on the columns Publisher and
>> Medium,
>> Prefetch() object doesn't seem to quite work for this case.
>>
>> I can of course filter-query for all PublisherMediumBilling and cache it
>> and do a in-memory Python JOIN. Is there a way to do through one of the ORM
>> Apis ?
>>
>
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