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"""
Tests for select_related()
``select_related()`` follows all relationships and pre-caches any foreign key
values so that complex trees can be fetched in a single query. However, this
isn't always a good idea, so the ``depth`` argument control how many "levels"
the select-related behavior will traverse.
"""
from django.contrib.contenttypes.fields import (
GenericForeignKey, GenericRelation,
)
from django.contrib.contenttypes.models import ContentType
from django.db import models
# Who remembers high school biology?
class Domain(models.Model):
name = models.CharField(max_length=50)
class Kingdom(models.Model):
name = models.CharField(max_length=50)
domain = models.ForeignKey(Domain, models.CASCADE)
class Phylum(models.Model):
name = models.CharField(max_length=50)
kingdom = models.ForeignKey(Kingdom, models.CASCADE)
class Klass(models.Model):
name = models.CharField(max_length=50)
phylum = models.ForeignKey(Phylum, models.CASCADE)
class Order(models.Model):
name = models.CharField(max_length=50)
klass = models.ForeignKey(Klass, models.CASCADE)
class Family(models.Model):
name = models.CharField(max_length=50)
order = models.ForeignKey(Order, models.CASCADE)
class Genus(models.Model):
name = models.CharField(max_length=50)
family = models.ForeignKey(Family, models.CASCADE)
class Species(models.Model):
name = models.CharField(max_length=50)
genus = models.ForeignKey(Genus, models.CASCADE)
# and we'll invent a new thing so we have a model with two foreign keys
class HybridSpecies(models.Model):
name = models.CharField(max_length=50)
parent_1 = models.ForeignKey(Species, models.CASCADE, related_name='child_1')
parent_2 = models.ForeignKey(Species, models.CASCADE, related_name='child_2')
class Topping(models.Model):
name = models.CharField(max_length=30)
class Pizza(models.Model):
name = models.CharField(max_length=100)
toppings = models.ManyToManyField(Topping)
class TaggedItem(models.Model):
tag = models.CharField(max_length=30)
content_type = models.ForeignKey(ContentType, models.CASCADE, related_name='select_related_tagged_items')
object_id = models.PositiveIntegerField()
content_object = GenericForeignKey('content_type', 'object_id')
class Bookmark(models.Model):
url = models.URLField()
tags = GenericRelation(TaggedItem)
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