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134 lines
3.4 KiB
Python
134 lines
3.4 KiB
Python
"""
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Many-to-one relationships
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To define a many-to-one relationship, use ``ForeignKey()``.
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"""
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from django.db import models
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class Reporter(models.Model):
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first_name = models.CharField(max_length=30)
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last_name = models.CharField(max_length=30)
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email = models.EmailField()
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def __str__(self):
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return "%s %s" % (self.first_name, self.last_name)
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class Article(models.Model):
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headline = models.CharField(max_length=100)
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pub_date = models.DateField()
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reporter = models.ForeignKey(Reporter, models.CASCADE)
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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 Country(models.Model):
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id = models.SmallAutoField(primary_key=True)
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name = models.CharField(max_length=50)
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class City(models.Model):
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id = models.BigAutoField(primary_key=True)
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country = models.ForeignKey(
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Country, models.CASCADE, related_name="cities", null=True
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)
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name = models.CharField(max_length=50)
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class District(models.Model):
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city = models.ForeignKey(City, models.CASCADE, related_name="districts", null=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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# If ticket #1578 ever slips back in, these models will not be able to be
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# created (the field names being lowercased versions of their opposite classes
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# is important here).
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class First(models.Model):
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second = models.IntegerField()
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class Second(models.Model):
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first = models.ForeignKey(First, models.CASCADE, related_name="the_first")
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# Protect against repetition of #1839, #2415 and #2536.
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class Third(models.Model):
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name = models.CharField(max_length=20)
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third = models.ForeignKey(
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"self", models.SET_NULL, null=True, related_name="child_set"
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)
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class Parent(models.Model):
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name = models.CharField(max_length=20, unique=True)
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bestchild = models.ForeignKey(
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"Child", models.SET_NULL, null=True, related_name="favored_by"
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)
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class ParentStringPrimaryKey(models.Model):
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name = models.CharField(primary_key=True, max_length=15)
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class Child(models.Model):
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name = models.CharField(max_length=20)
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parent = models.ForeignKey(Parent, models.CASCADE)
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class ChildNullableParent(models.Model):
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parent = models.ForeignKey(Parent, models.CASCADE, null=True)
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class ChildStringPrimaryKeyParent(models.Model):
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parent = models.ForeignKey(ParentStringPrimaryKey, on_delete=models.CASCADE)
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class ToFieldChild(models.Model):
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parent = models.ForeignKey(
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Parent, models.CASCADE, to_field="name", related_name="to_field_children"
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)
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# Multiple paths to the same model (#7110, #7125)
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class Category(models.Model):
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name = models.CharField(max_length=20)
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def __str__(self):
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return self.name
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class Record(models.Model):
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category = models.ForeignKey(Category, models.CASCADE)
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class Relation(models.Model):
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left = models.ForeignKey(Record, models.CASCADE, related_name="left_set")
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right = models.ForeignKey(Record, models.CASCADE, related_name="right_set")
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def __str__(self):
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return "%s - %s" % (self.left.category.name, self.right.category.name)
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# Test related objects visibility.
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class SchoolManager(models.Manager):
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def get_queryset(self):
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return super().get_queryset().filter(is_public=True)
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class School(models.Model):
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is_public = models.BooleanField(default=False)
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objects = SchoolManager()
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class Student(models.Model):
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school = models.ForeignKey(School, models.CASCADE)
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