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