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"""
Multiple many-to-many relationships between the same two tables
In this example, an ``Article`` can have many "primary" ``Category`` objects
and many "secondary" ``Category`` objects.
Set ``related_name`` to designate what the reverse relationship is called.
"""
from django.db import models
class Category(models.Model):
name = models.CharField(max_length=20)
class Meta:
ordering = ("name",)
def __str__(self):
return self.name
class Article(models.Model):
headline = models.CharField(max_length=50)
pub_date = models.DateTimeField()
primary_categories = models.ManyToManyField(
Category, related_name="primary_article_set"
)
secondary_categories = models.ManyToManyField(
Category, related_name="secondary_article_set"
)
class Meta:
ordering = ("pub_date",)
def __str__(self):
return self.headline
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