1 """

     2 25. Reverse lookups

     3 

     4 This demonstrates the reverse lookup features of the database API.

     5 """

     6 

     7 from django.db import models

     8 

     9 class User(models.Model):

    10     name = models.CharField(maxlength=200)

    11 

    12     def __str__(self):

    13         return self.name

    14 

    15 class Poll(models.Model):

    16     question = models.CharField(maxlength=200)

    17     creator = models.ForeignKey(User)

    18 

    19     def __str__(self):

    20         return self.question

    21 

    22 class Choice(models.Model):

    23     name = models.CharField(maxlength=100)

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

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

    26 

    27     def __str(self):

    28         return self.name

    29 

    30 __test__ = {'API_TESTS':"""

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

    32 >>> john.save()

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

    34 >>> jim.save()

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

    36 >>> first_poll.save()

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

    38 >>> second_poll.save()

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

    40 >>> new_choice.save()

    41 

    42 >>> # Reverse lookups by field name:

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

    44 <User: John Doe>

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

    46 <User: Jim Bo>

    47 

    48 >>> # Reverse lookups by related_name:

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

    50 <Poll: What's the first question?>

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

    52 <Poll: What's the second question?>

    53 

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

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

    56 Traceback (most recent call last):

    57     ...

    58 TypeError: Cannot resolve keyword 'choice' into field

    59 """}