Re: Basic M2M Self Reference Through Question

On Sep 2, 2015 9:51 AM, "jeff newburn" <jeffnb@gmail.com> wrote:
>
> I apologize if this is basic and I am just missing something in the django docs.  The Django ORM allows you to do a self reference through another table.  I understand everything about this process EXCEPT how Django determines which of the foreign keys to use for each side of the M2M relationship.
>
> class MyUser(...):
>     connections = models.ManyToManyField('self', through=Relationship, symmetrical=False)
>
> class Relationship(...):
>     follower = models.ForeignKey(MyUser)
>     following = models.ForeignKey(MyUser)
>
> So in the psuedocode example above how does Django ORM know which of the 2 foreign key fields to connect to?  Does it just assume the first field is the one to use?  Thanks for any help on this.
>

When you have multiple references to the same model, you have to do a bit of extra work to tell Django how you want things to line up. I think what you need to do is specify the 'through_fields' on the M2M, and set appropriate 'related_name' arguments for the FK's.

https://docs.djangoproject.com/en/1.8/ref/models/fields/#django.db.models.ManyToManyField.through_fields

-James

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