Django documentation

24. Mutually referential many-to-one relationships

This example is for Django's SVN release, which can be significantly different from previous releases. Get old examples here: 0.96, 0.95.

Strings can be used instead of model literals to set up “lazy” relations.

Model source code

from django.db.models import *

class Parent(Model):
    name = CharField(max_length=100, core=True)
    
    # Use a simple string for forward declarations.
    bestchild = ForeignKey("Child", null=True, related_name="favoured_by")

class Child(Model):
    name = CharField(max_length=100)
    
    # You can also explicitally specify the related app.
    parent = ForeignKey("mutually_referential.Parent")

Sample API usage

This sample code assumes the above models have been saved in a file mysite/models.py. 

>>> from mysite.models import 

# Create a Parent
>>> q = Parent(name='Elizabeth')
>>> q.save()

# Create some children
>>> c = q.child_set.create(name='Charles')
>>> e = q.child_set.create(name='Edward')

# Set the best child
>>> q.bestchild = c
>>> q.save()

>>> q.delete()

Contents