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