Django-1.2.1/tests/modeltests/m2m_intermediary/models.py

   1 """
   2 9. Many-to-many relationships via an intermediary table
   3
   4 For many-to-many relationships that need extra fields on the intermediary
   5 table, use an intermediary model.
   6
   7 In this example, an ``Article`` can have multiple ``Reporter`` objects, and
   8 each ``Article``-``Reporter`` combination (a ``Writer``) has a ``position``
   9 field, which specifies the ``Reporter``'s position for the given article
  10 (e.g. "Staff writer").
  11 """
  12
  13 from django.db import models
  14
  15 class Reporter(models.Model):
  16     first_name = models.CharField(max_length=30)
  17     last_name = models.CharField(max_length=30)
  18
  19     def __unicode__(self):
  20         return u"%s %s" % (self.first_name, self.last_name)
  21
  22 class Article(models.Model):
  23     headline = models.CharField(max_length=100)
  24     pub_date = models.DateField()
  25
  26     def __unicode__(self):
  27         return self.headline
  28
  29 class Writer(models.Model):
  30     reporter = models.ForeignKey(Reporter)
  31     article = models.ForeignKey(Article)
  32     position = models.CharField(max_length=100)
  33
  34     def __unicode__(self):
  35         return u'%s (%s)' % (self.reporter, self.position)
  36
  37 __test__ = {'API_TESTS':"""
  38 # Create a few Reporters.
  39 >>> r1 = Reporter(first_name='John', last_name='Smith')
  40 >>> r1.save()
  41 >>> r2 = Reporter(first_name='Jane', last_name='Doe')
  42 >>> r2.save()
  43
  44 # Create an Article.
  45 >>> from datetime import datetime
  46 >>> a = Article(headline='This is a test', pub_date=datetime(2005, 7, 27))
  47 >>> a.save()
  48
  49 # Create a few Writers.
  50 >>> w1 = Writer(reporter=r1, article=a, position='Main writer')
  51 >>> w1.save()
  52 >>> w2 = Writer(reporter=r2, article=a, position='Contributor')
  53 >>> w2.save()
  54
  55 # Play around with the API.
  56 >>> a.writer_set.select_related().order_by('-position')
  57 [<Writer: John Smith (Main writer)>, <Writer: Jane Doe (Contributor)>]
  58 >>> w1.reporter
  59 <Reporter: John Smith>
  60 >>> w2.reporter
  61 <Reporter: Jane Doe>
  62 >>> w1.article
  63 <Article: This is a test>
  64 >>> w2.article
  65 <Article: This is a test>
  66 >>> r1.writer_set.all()
  67 [<Writer: John Smith (Main writer)>]
  68 """}