"""

5. Many-to-many relationships

To define a many-to-many relationship, use ``ManyToManyField()``.

In this example, an ``Article`` can be published in multiple ``Publication``

objects, and a ``Publication`` has multiple ``Article`` objects.

"""

from django.db import models

class Publication(models.Model):

    title = models.CharField(max_length=30)

    def __unicode__(self):

        return self.title

    class Meta:

        ordering = ('title',)

class Article(models.Model):

    headline = models.CharField(max_length=100)

    publications = models.ManyToManyField(Publication)

    def __unicode__(self):

        return self.headline

    class Meta:

        ordering = ('headline',)