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450 lines
14 KiB
Python
450 lines
14 KiB
Python
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.core.checks import Error
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from django.core.exceptions import FieldDoesNotExist, FieldError
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from django.db import models
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from django.test import SimpleTestCase
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from django.test.utils import isolate_apps
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@isolate_apps("model_inheritance")
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class AbstractInheritanceTests(SimpleTestCase):
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def test_single_parent(self):
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class AbstractBase(models.Model):
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name = models.CharField(max_length=30)
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class Meta:
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abstract = True
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class AbstractDescendant(AbstractBase):
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name = models.CharField(max_length=50)
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class Meta:
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abstract = True
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class DerivedChild(AbstractBase):
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name = models.CharField(max_length=50)
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class DerivedGrandChild(AbstractDescendant):
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pass
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self.assertEqual(AbstractDescendant._meta.get_field("name").max_length, 50)
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self.assertEqual(DerivedChild._meta.get_field("name").max_length, 50)
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self.assertEqual(DerivedGrandChild._meta.get_field("name").max_length, 50)
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def test_multiple_inheritance_allows_inherited_field(self):
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"""
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Single layer multiple inheritance is as expected, deriving the
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inherited field from the first base.
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"""
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class ParentA(models.Model):
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name = models.CharField(max_length=255)
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class Meta:
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abstract = True
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class ParentB(models.Model):
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name = models.IntegerField()
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class Meta:
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abstract = True
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class Child(ParentA, ParentB):
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pass
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self.assertEqual(Child.check(), [])
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inherited_field = Child._meta.get_field("name")
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self.assertIsInstance(inherited_field, models.CharField)
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self.assertEqual(inherited_field.max_length, 255)
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def test_diamond_shaped_multiple_inheritance_is_depth_first(self):
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"""
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In contrast to standard Python MRO, resolution of inherited fields is
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strictly depth-first, rather than breadth-first in diamond-shaped cases.
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This is because a copy of the parent field descriptor is placed onto
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the model class in ModelBase.__new__(), rather than the attribute
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lookup going via bases. (It only **looks** like inheritance.)
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Here, Child inherits name from Root, rather than ParentB.
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"""
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class Root(models.Model):
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name = models.CharField(max_length=255)
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class Meta:
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abstract = True
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class ParentA(Root):
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class Meta:
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abstract = True
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class ParentB(Root):
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name = models.IntegerField()
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class Meta:
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abstract = True
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class Child(ParentA, ParentB):
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pass
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self.assertEqual(Child.check(), [])
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inherited_field = Child._meta.get_field("name")
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self.assertIsInstance(inherited_field, models.CharField)
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self.assertEqual(inherited_field.max_length, 255)
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def test_target_field_may_be_pushed_down(self):
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"""
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Where the Child model needs to inherit a field from a different base
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than that given by depth-first resolution, the target field can be
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**pushed down** by being re-declared.
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"""
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class Root(models.Model):
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name = models.CharField(max_length=255)
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class Meta:
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abstract = True
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class ParentA(Root):
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class Meta:
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abstract = True
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class ParentB(Root):
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name = models.IntegerField()
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class Meta:
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abstract = True
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class Child(ParentA, ParentB):
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name = models.IntegerField()
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self.assertEqual(Child.check(), [])
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inherited_field = Child._meta.get_field("name")
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self.assertIsInstance(inherited_field, models.IntegerField)
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def test_multiple_inheritance_cannot_shadow_concrete_inherited_field(self):
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class ConcreteParent(models.Model):
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name = models.CharField(max_length=255)
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class AbstractParent(models.Model):
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name = models.IntegerField()
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class Meta:
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abstract = True
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class FirstChild(ConcreteParent, AbstractParent):
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pass
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class AnotherChild(AbstractParent, ConcreteParent):
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pass
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self.assertIsInstance(FirstChild._meta.get_field("name"), models.CharField)
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self.assertEqual(
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AnotherChild.check(),
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[
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Error(
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"The field 'name' clashes with the field 'name' "
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"from model 'model_inheritance.concreteparent'.",
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obj=AnotherChild._meta.get_field("name"),
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id="models.E006",
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)
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],
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)
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def test_virtual_field(self):
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class RelationModel(models.Model):
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content_type = models.ForeignKey(ContentType, models.CASCADE)
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object_id = models.PositiveIntegerField()
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content_object = GenericForeignKey("content_type", "object_id")
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class RelatedModelAbstract(models.Model):
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field = GenericRelation(RelationModel)
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class Meta:
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abstract = True
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class ModelAbstract(models.Model):
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field = models.CharField(max_length=100)
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class Meta:
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abstract = True
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class OverrideRelatedModelAbstract(RelatedModelAbstract):
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field = models.CharField(max_length=100)
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class ExtendModelAbstract(ModelAbstract):
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field = GenericRelation(RelationModel)
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self.assertIsInstance(
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OverrideRelatedModelAbstract._meta.get_field("field"), models.CharField
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)
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self.assertIsInstance(
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ExtendModelAbstract._meta.get_field("field"), GenericRelation
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)
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def test_cannot_override_indirect_abstract_field(self):
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class AbstractBase(models.Model):
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name = models.CharField(max_length=30)
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class Meta:
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abstract = True
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class ConcreteDescendant(AbstractBase):
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pass
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msg = (
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"Local field 'name' in class 'Descendant' clashes with field of "
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"the same name from base class 'ConcreteDescendant'."
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)
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with self.assertRaisesMessage(FieldError, msg):
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class Descendant(ConcreteDescendant):
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name = models.IntegerField()
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def test_override_field_with_attr(self):
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class AbstractBase(models.Model):
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first_name = models.CharField(max_length=50)
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last_name = models.CharField(max_length=50)
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middle_name = models.CharField(max_length=30)
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full_name = models.CharField(max_length=150)
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class Meta:
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abstract = True
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class Descendant(AbstractBase):
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middle_name = None
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def full_name(self):
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return self.first_name + self.last_name
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msg = "Descendant has no field named %r"
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with self.assertRaisesMessage(FieldDoesNotExist, msg % "middle_name"):
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Descendant._meta.get_field("middle_name")
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with self.assertRaisesMessage(FieldDoesNotExist, msg % "full_name"):
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Descendant._meta.get_field("full_name")
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def test_overriding_field_removed_by_concrete_model(self):
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class AbstractModel(models.Model):
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foo = models.CharField(max_length=30)
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class Meta:
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abstract = True
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class RemovedAbstractModelField(AbstractModel):
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foo = None
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class OverrideRemovedFieldByConcreteModel(RemovedAbstractModelField):
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foo = models.CharField(max_length=50)
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self.assertEqual(
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OverrideRemovedFieldByConcreteModel._meta.get_field("foo").max_length, 50
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)
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def test_shadowed_fkey_id(self):
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class Foo(models.Model):
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pass
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class AbstractBase(models.Model):
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foo = models.ForeignKey(Foo, models.CASCADE)
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class Meta:
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abstract = True
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class Descendant(AbstractBase):
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foo_id = models.IntegerField()
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self.assertEqual(
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Descendant.check(),
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[
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Error(
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"The field 'foo_id' clashes with the field 'foo' "
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"from model 'model_inheritance.descendant'.",
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obj=Descendant._meta.get_field("foo_id"),
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id="models.E006",
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)
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],
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)
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def test_shadow_related_name_when_set_to_none(self):
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class AbstractBase(models.Model):
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bar = models.IntegerField()
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class Meta:
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abstract = True
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class Foo(AbstractBase):
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bar = None
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foo = models.IntegerField()
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class Bar(models.Model):
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bar = models.ForeignKey(Foo, models.CASCADE, related_name="bar")
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self.assertEqual(Bar.check(), [])
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def test_reverse_foreign_key(self):
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class AbstractBase(models.Model):
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foo = models.CharField(max_length=100)
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class Meta:
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abstract = True
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class Descendant(AbstractBase):
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pass
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class Foo(models.Model):
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foo = models.ForeignKey(Descendant, models.CASCADE, related_name="foo")
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self.assertEqual(
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Foo._meta.get_field("foo").check(),
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[
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Error(
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"Reverse accessor 'Descendant.foo' for "
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"'model_inheritance.Foo.foo' clashes with field name "
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"'model_inheritance.Descendant.foo'.",
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hint=(
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"Rename field 'model_inheritance.Descendant.foo', or "
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"add/change a related_name argument to the definition "
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"for field 'model_inheritance.Foo.foo'."
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),
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obj=Foo._meta.get_field("foo"),
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id="fields.E302",
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),
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Error(
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"Reverse query name for 'model_inheritance.Foo.foo' "
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"clashes with field name "
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"'model_inheritance.Descendant.foo'.",
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hint=(
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"Rename field 'model_inheritance.Descendant.foo', or "
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"add/change a related_name argument to the definition "
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"for field 'model_inheritance.Foo.foo'."
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),
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obj=Foo._meta.get_field("foo"),
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id="fields.E303",
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),
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],
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)
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def test_multi_inheritance_field_clashes(self):
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class AbstractBase(models.Model):
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name = models.CharField(max_length=30)
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class Meta:
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abstract = True
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class ConcreteBase(AbstractBase):
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pass
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class AbstractDescendant(ConcreteBase):
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class Meta:
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abstract = True
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class ConcreteDescendant(AbstractDescendant):
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name = models.CharField(max_length=100)
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self.assertEqual(
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ConcreteDescendant.check(),
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[
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Error(
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"The field 'name' clashes with the field 'name' from "
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"model 'model_inheritance.concretebase'.",
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obj=ConcreteDescendant._meta.get_field("name"),
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id="models.E006",
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)
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],
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)
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def test_override_one2one_relation_auto_field_clashes(self):
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class ConcreteParent(models.Model):
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name = models.CharField(max_length=255)
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class AbstractParent(models.Model):
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name = models.IntegerField()
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class Meta:
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abstract = True
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msg = (
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"Auto-generated field 'concreteparent_ptr' in class 'Descendant' "
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"for parent_link to base class 'ConcreteParent' clashes with "
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"declared field of the same name."
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)
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with self.assertRaisesMessage(FieldError, msg):
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class Descendant(ConcreteParent, AbstractParent):
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concreteparent_ptr = models.CharField(max_length=30)
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def test_abstract_model_with_regular_python_mixin_mro(self):
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class AbstractModel(models.Model):
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name = models.CharField(max_length=255)
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age = models.IntegerField()
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class Meta:
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abstract = True
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class Mixin:
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age = None
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class Mixin2:
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age = 2
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class DescendantMixin(Mixin):
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pass
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class ConcreteModel(models.Model):
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foo = models.IntegerField()
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class ConcreteModel2(ConcreteModel):
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age = models.SmallIntegerField()
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def fields(model):
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if not hasattr(model, "_meta"):
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return []
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return [(f.name, f.__class__) for f in model._meta.get_fields()]
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model_dict = {"__module__": "model_inheritance"}
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model1 = type("Model1", (AbstractModel, Mixin), model_dict.copy())
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model2 = type("Model2", (Mixin2, AbstractModel), model_dict.copy())
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model3 = type("Model3", (DescendantMixin, AbstractModel), model_dict.copy())
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model4 = type("Model4", (Mixin2, Mixin, AbstractModel), model_dict.copy())
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model5 = type(
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"Model5", (Mixin2, ConcreteModel2, Mixin, AbstractModel), model_dict.copy()
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)
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self.assertEqual(
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fields(model1),
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[
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("id", models.AutoField),
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("name", models.CharField),
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("age", models.IntegerField),
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],
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)
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self.assertEqual(
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fields(model2), [("id", models.AutoField), ("name", models.CharField)]
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)
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self.assertEqual(getattr(model2, "age"), 2)
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self.assertEqual(
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fields(model3), [("id", models.AutoField), ("name", models.CharField)]
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)
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self.assertEqual(
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fields(model4), [("id", models.AutoField), ("name", models.CharField)]
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)
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self.assertEqual(getattr(model4, "age"), 2)
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self.assertEqual(
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fields(model5),
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[
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("id", models.AutoField),
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("foo", models.IntegerField),
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("concretemodel_ptr", models.OneToOneField),
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("age", models.SmallIntegerField),
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("concretemodel2_ptr", models.OneToOneField),
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("name", models.CharField),
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],
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)
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