On Mon, 2009-06-01 at 16:01 -0700, Ben Adida wrote:
> I have a ManyToMany self relationship with a custom join table (I
> don't think the self-reference is important to the problem, but it
> might be, so I'm mentioning it):
>
> class Documents
> related_docs = models.ManyToManyField("self",
> through='DocumentRels')
>
> DocumentRels is a table that maps one document to another, with a
> relationship type.
>
> If I want all documents related to doc_0, I can just do:
>
> doc_0.related_docs
>
> But what if I want all documents related to doc_0 where I specify an
> extra constraint on the join table, e.g. a value for
> DocumentRels.relationship? Is there a way to do that without custom
> SQL?
You will not need custom sql, because DocumentRels is going to be a
Model. When you want to filter based on DocumentRels.relationship, you
will either use:
DocumentRels.objects.filter()
or go through the RelatedManagers that are added to your Document
model for the ForeignKeys in DocumentRels. The reference is here:
http://docs.djangoproject.com/en/dev/topics/db/models/#extra-fields-on-many-to-many-relationships
For code that exactly fits your case, see PersonSelfRefM2M in:
http://code.djangoproject.com/browser/django/trunk/tests/modeltests/m2m_through/models.py
sdc
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