[Django]-Django model with 2 foreign keys from the same table

I think what you’re looking for is the related_name property on ForeignKeyFields. This will allow you to reference the same table, but give django special names for the relationship.

More Info:

• https://docs.djangoproject.com/en/dev/ref/models/fields/#django.db.models.ForeignKey.related_name
• https://docs.djangoproject.com/en/dev/topics/db/queries/#backwards-related-objects
• https://docs.djangoproject.com/en/dev/topics/db/examples/many_to_one/

Using related_name was my solution:

class Sample(models.model):
    ...

class Mymodel(models.model):
    example1 = models.ForeignKey(Sample, related_name='sample1')
    example2 = models.ForeignKey(Sample, related_name='sample2')

From the error message, it sounds like you’re trying to put two foreign keys to the same object on an intermediary table used via the through argument to ManyToManyField, the documentation for which states:

When you set up the intermediary
model, you explicitly specify foreign
keys to the models that are involved
in the ManyToMany relation. This
explicit declaration defines how the
two models are related.

There are a few restrictions on the
intermediate model:

• Your intermediate model must contain one – and only one – foreign key to
  the target model (this would be Person
  in our example). If you have more than
  one foreign key, a validation error
  will be raised.
• Your intermediate model must contain one – and only one – foreign key to
  the source model (this would be Group
  in our example). If you have more than
  one foreign key, a validation error
  will be raised.

The fact that two columns are part of one table implies that the two fields are related, therefor to reference them individually is not ideal. The ForeignKey of your model should be the primary key of the table you are referencing:

event = models.ForeignKey('event')

You would then reference the columns as such:

foo.event.actor
foo.event.receiver

If you wish you could also change the way your class/model references the foreign attributes with properties. In your class you would do the following:

@property
def actor(self):
  return self.event.actor
@property
def receiver(self):
  return self.event.receiver

This would allow you to then call foo.actor and foo.receiver but I believe the longer, foo.event.actor would be more pythonic