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37 lines
969 B
Python
37 lines
969 B
Python
"""
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Relating an object to itself, many-to-one
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To define a many-to-one relationship between a model and itself, use
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``ForeignKey('self', ...)``.
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In this example, a ``Category`` is related to itself. That is, each
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``Category`` has a parent ``Category``.
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Set ``related_name`` to designate what the reverse relationship is called.
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"""
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from django.db import models
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class Category(models.Model):
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name = models.CharField(max_length=20)
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parent = models.ForeignKey(
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"self", models.SET_NULL, blank=True, null=True, related_name="child_set"
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)
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def __str__(self):
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return self.name
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class Person(models.Model):
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full_name = models.CharField(max_length=20)
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mother = models.ForeignKey(
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"self", models.SET_NULL, null=True, related_name="mothers_child_set"
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)
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father = models.ForeignKey(
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"self", models.SET_NULL, null=True, related_name="fathers_child_set"
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)
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def __str__(self):
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return self.full_name
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