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93 lines
2.3 KiB
Python
93 lines
2.3 KiB
Python
"""
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Many-to-many relationships
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To define a many-to-many relationship, use ``ManyToManyField()``.
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In this example, an ``Article`` can be published in multiple ``Publication``
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objects, and a ``Publication`` has multiple ``Article`` objects.
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"""
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from django.db import models
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class Publication(models.Model):
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title = models.CharField(max_length=30)
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class Meta:
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ordering = ("title",)
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def __str__(self):
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return self.title
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class Tag(models.Model):
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id = models.BigAutoField(primary_key=True)
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name = models.CharField(max_length=50)
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def __str__(self):
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return self.name
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class NoDeletedArticleManager(models.Manager):
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def get_queryset(self):
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return super().get_queryset().exclude(headline="deleted")
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class Article(models.Model):
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headline = models.CharField(max_length=100)
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# Assign a string as name to make sure the intermediary model is
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# correctly created. Refs #20207
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publications = models.ManyToManyField(Publication, name="publications")
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tags = models.ManyToManyField(Tag, related_name="tags")
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authors = models.ManyToManyField("User", through="UserArticle")
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objects = NoDeletedArticleManager()
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class Meta:
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ordering = ("headline",)
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def __str__(self):
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return self.headline
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class User(models.Model):
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username = models.CharField(max_length=20, unique=True)
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def __str__(self):
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return self.username
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class UserArticle(models.Model):
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user = models.ForeignKey(User, models.CASCADE, to_field="username")
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article = models.ForeignKey(Article, models.CASCADE)
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# Models to test correct related_name inheritance
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class AbstractArticle(models.Model):
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class Meta:
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abstract = True
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publications = models.ManyToManyField(
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Publication, name="publications", related_name="+"
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)
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class InheritedArticleA(AbstractArticle):
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pass
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class InheritedArticleB(AbstractArticle):
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pass
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class NullableTargetArticle(models.Model):
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headline = models.CharField(max_length=100)
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publications = models.ManyToManyField(
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Publication, through="NullablePublicationThrough"
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)
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class NullablePublicationThrough(models.Model):
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article = models.ForeignKey(NullableTargetArticle, models.CASCADE)
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publication = models.ForeignKey(Publication, models.CASCADE, null=True)
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