mirror of https://github.com/django/django.git
193 lines
4.0 KiB
Python
193 lines
4.0 KiB
Python
"""
|
|
28. Many-to-many relationships between the same two tables
|
|
|
|
In this example, A Person can have many friends, who are also people. Friendship is a
|
|
symmetrical relationship - if I am your friend, you are my friend.
|
|
|
|
A person can also have many idols - but while I may idolize you, you may not think
|
|
the same of me. 'Idols' is an example of a non-symmetrical m2m field. Only recursive
|
|
m2m fields may be non-symmetrical, and they are symmetrical by default.
|
|
|
|
This test validates that the m2m table will create a mangled name for the m2m table if
|
|
there will be a clash, and tests that symmetry is preserved where appropriate.
|
|
"""
|
|
|
|
from django.db import models
|
|
|
|
class Person(models.Model):
|
|
name = models.CharField(maxlength=20)
|
|
friends = models.ManyToManyField('self')
|
|
idols = models.ManyToManyField('self', symmetrical=False, related_name='stalkers')
|
|
|
|
def __str__(self):
|
|
return self.name
|
|
|
|
__test__ = {'API_TESTS':"""
|
|
>>> a = Person(name='Anne')
|
|
>>> a.save()
|
|
>>> b = Person(name='Bill')
|
|
>>> b.save()
|
|
>>> c = Person(name='Chuck')
|
|
>>> c.save()
|
|
>>> d = Person(name='David')
|
|
>>> d.save()
|
|
|
|
# Add some friends in the direction of field definition
|
|
# Anne is friends with Bill and Chuck
|
|
>>> a.friends.add(b,c)
|
|
|
|
# David is friends with Anne and Chuck - add in reverse direction
|
|
>>> d.friends.add(a,c)
|
|
|
|
# Who is friends with Anne?
|
|
>>> a.friends.all()
|
|
[<Person: Bill>, <Person: Chuck>, <Person: David>]
|
|
|
|
# Who is friends with Bill?
|
|
>>> b.friends.all()
|
|
[<Person: Anne>]
|
|
|
|
# Who is friends with Chuck?
|
|
>>> c.friends.all()
|
|
[<Person: Anne>, <Person: David>]
|
|
|
|
# Who is friends with David?
|
|
>>> d.friends.all()
|
|
[<Person: Anne>, <Person: Chuck>]
|
|
|
|
# Bill is already friends with Anne - add Anne again, but in the reverse direction
|
|
>>> b.friends.add(a)
|
|
|
|
# Who is friends with Anne?
|
|
>>> a.friends.all()
|
|
[<Person: Bill>, <Person: Chuck>, <Person: David>]
|
|
|
|
# Who is friends with Bill?
|
|
>>> b.friends.all()
|
|
[<Person: Anne>]
|
|
|
|
# Remove Anne from Bill's friends
|
|
>>> b.friends.remove(a)
|
|
|
|
# Who is friends with Anne?
|
|
>>> a.friends.all()
|
|
[<Person: Chuck>, <Person: David>]
|
|
|
|
# Who is friends with Bill?
|
|
>>> b.friends.all()
|
|
[]
|
|
|
|
# Clear Anne's group of friends
|
|
>>> a.friends.clear()
|
|
|
|
# Who is friends with Anne?
|
|
>>> a.friends.all()
|
|
[]
|
|
|
|
# Reverse relationships should also be gone
|
|
# Who is friends with Chuck?
|
|
>>> c.friends.all()
|
|
[<Person: David>]
|
|
|
|
# Who is friends with David?
|
|
>>> d.friends.all()
|
|
[<Person: Chuck>]
|
|
|
|
|
|
# Add some idols in the direction of field definition
|
|
# Anne idolizes Bill and Chuck
|
|
>>> a.idols.add(b,c)
|
|
|
|
# Bill idolizes Anne right back
|
|
>>> b.idols.add(a)
|
|
|
|
# David is idolized by Anne and Chuck - add in reverse direction
|
|
>>> d.stalkers.add(a,c)
|
|
|
|
# Who are Anne's idols?
|
|
>>> a.idols.all()
|
|
[<Person: Bill>, <Person: Chuck>, <Person: David>]
|
|
|
|
# Who is stalking Anne?
|
|
>>> a.stalkers.all()
|
|
[<Person: Bill>]
|
|
|
|
# Who are Bill's idols?
|
|
>>> b.idols.all()
|
|
[<Person: Anne>]
|
|
|
|
# Who is stalking Bill?
|
|
>>> b.stalkers.all()
|
|
[<Person: Anne>]
|
|
|
|
# Who are Chuck's idols?
|
|
>>> c.idols.all()
|
|
[<Person: David>]
|
|
|
|
# Who is stalking Chuck?
|
|
>>> c.stalkers.all()
|
|
[<Person: Anne>]
|
|
|
|
# Who are David's idols?
|
|
>>> d.idols.all()
|
|
[]
|
|
|
|
# Who is stalking David
|
|
>>> d.stalkers.all()
|
|
[<Person: Anne>, <Person: Chuck>]
|
|
|
|
# Bill is already being stalked by Anne - add Anne again, but in the reverse direction
|
|
>>> b.stalkers.add(a)
|
|
|
|
# Who are Anne's idols?
|
|
>>> a.idols.all()
|
|
[<Person: Bill>, <Person: Chuck>, <Person: David>]
|
|
|
|
# Who is stalking Anne?
|
|
[<Person: Bill>]
|
|
|
|
# Who are Bill's idols
|
|
>>> b.idols.all()
|
|
[<Person: Anne>]
|
|
|
|
# Who is stalking Bill?
|
|
>>> b.stalkers.all()
|
|
[<Person: Anne>]
|
|
|
|
# Remove Anne from Bill's list of stalkers
|
|
>>> b.stalkers.remove(a)
|
|
|
|
# Who are Anne's idols?
|
|
>>> a.idols.all()
|
|
[<Person: Chuck>, <Person: David>]
|
|
|
|
# Who is stalking Anne?
|
|
>>> a.stalkers.all()
|
|
[<Person: Bill>]
|
|
|
|
# Who are Bill's idols?
|
|
>>> b.idols.all()
|
|
[<Person: Anne>]
|
|
|
|
# Who is stalking Bill?
|
|
>>> b.stalkers.all()
|
|
[]
|
|
|
|
# Clear Anne's group of idols
|
|
>>> a.idols.clear()
|
|
|
|
# Who are Anne's idols
|
|
>>> a.idols.all()
|
|
[]
|
|
|
|
# Reverse relationships should also be gone
|
|
# Who is stalking Chuck?
|
|
>>> c.stalkers.all()
|
|
[]
|
|
|
|
# Who is friends with David?
|
|
>>> d.stalkers.all()
|
|
[<Person: Chuck>]
|
|
|
|
"""}
|