"""

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>]

"""}