"""

25. Reverse lookups

This demonstrates the reverse lookup features of the database API.

"""

from django.db import models

class User(models.Model):

    name = models.CharField(maxlength=200)

    def __str__(self):

        return self.name

class Poll(models.Model):

    question = models.CharField(maxlength=200)

    creator = models.ForeignKey(User)

    def __str__(self):

        return self.question

class Choice(models.Model):

    name = models.CharField(maxlength=100)

    poll = models.ForeignKey(Poll, related_name="poll_choice")

    related_poll = models.ForeignKey(Poll, related_name="related_choice")

    def __str(self):

        return self.name

__test__ = {'API_TESTS':"""

>>> john = User(name="John Doe")

>>> john.save()

>>> jim = User(name="Jim Bo")

>>> jim.save()

>>> first_poll = Poll(question="What's the first question?", creator=john)

>>> first_poll.save()

>>> second_poll = Poll(question="What's the second question?", creator=jim)

>>> second_poll.save()

>>> new_choice = Choice(poll=first_poll, related_poll=second_poll, name="This is the answer.")

>>> new_choice.save()

>>> # Reverse lookups by field name:

>>> User.objects.get(poll__question__exact="What's the first question?")

<User: John Doe>

>>> User.objects.get(poll__question__exact="What's the second question?")

<User: Jim Bo>

>>> # Reverse lookups by related_name:

>>> Poll.objects.get(poll_choice__name__exact="This is the answer.")

<Poll: What's the first question?>

>>> Poll.objects.get(related_choice__name__exact="This is the answer.")

<Poll: What's the second question?>

>>> # If a related_name is given you can't use the field name instead:

>>> Poll.objects.get(choice__name__exact="This is the answer")

Traceback (most recent call last):

    ...

TypeError: Cannot resolve keyword 'choice' into field

"""}