1 """

     2 12. Relating a model to another model more than once

     3 

     4 In this example, a ``Person`` can have a ``mother`` and ``father`` -- both of

     5 which are other ``Person`` objects.

     6 

     7 Set ``related_name`` to designate what the reverse relationship is called.

     8 """

     9 

    10 from django.db import models

    11 

    12 class Person(models.Model):

    13     full_name = models.CharField(maxlength=20)

    14     mother = models.ForeignKey('self', null=True, related_name='mothers_child_set')

    15     father = models.ForeignKey('self', null=True, related_name='fathers_child_set')

    16 

    17     def __str__(self):

    18         return self.full_name

    19 

    20 __test__ = {'API_TESTS':"""

    21 # Create two Person objects -- the mom and dad in our family.

    22 >>> dad = Person(full_name='John Smith Senior', mother=None, father=None)

    23 >>> dad.save()

    24 >>> mom = Person(full_name='Jane Smith', mother=None, father=None)

    25 >>> mom.save()

    26 

    27 # Give mom and dad a kid.

    28 >>> kid = Person(full_name='John Smith Junior', mother=mom, father=dad)

    29 >>> kid.save()

    30 

    31 >>> kid.mother

    32 <Person: Jane Smith>

    33 >>> kid.father

    34 <Person: John Smith Senior>

    35 >>> dad.fathers_child_set.all()

    36 [<Person: John Smith Junior>]

    37 >>> mom.mothers_child_set.all()

    38 [<Person: John Smith Junior>]

    39 >>> kid.mothers_child_set.all()

    40 []

    41 >>> kid.fathers_child_set.all()

    42 []

    43 """}