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from decimal import Decimal
from django.apps import apps
from django.core import checks
from django.core.exceptions import FieldError
from django.db import models
from django.test import TestCase, skipIfDBFeature
from django.test.utils import isolate_apps
from .models import Bar, FkToChar, Foo, PrimaryKeyCharModel
class ForeignKeyTests(TestCase):
def test_callable_default(self):
"""A lazy callable may be used for ForeignKey.default."""
a = Foo.objects.create(id=1, a="abc", d=Decimal("12.34"))
b = Bar.objects.create(b="bcd")
self.assertEqual(b.a, a)
@skipIfDBFeature("interprets_empty_strings_as_nulls")
def test_empty_string_fk(self):
"""
Empty strings foreign key values don't get converted to None (#19299).
"""
char_model_empty = PrimaryKeyCharModel.objects.create(string="")
fk_model_empty = FkToChar.objects.create(out=char_model_empty)
fk_model_empty = FkToChar.objects.select_related("out").get(
id=fk_model_empty.pk
)
self.assertEqual(fk_model_empty.out, char_model_empty)
@isolate_apps("model_fields")
def test_warning_when_unique_true_on_fk(self):
class Foo(models.Model):
pass
class FKUniqueTrue(models.Model):
fk_field = models.ForeignKey(Foo, models.CASCADE, unique=True)
model = FKUniqueTrue()
expected_warnings = [
checks.Warning(
"Setting unique=True on a ForeignKey has the same effect as using a "
"OneToOneField.",
hint=(
"ForeignKey(unique=True) is usually better served by a "
"OneToOneField."
),
obj=FKUniqueTrue.fk_field.field,
id="fields.W342",
)
]
warnings = model.check()
self.assertEqual(warnings, expected_warnings)
def test_related_name_converted_to_text(self):
rel_name = Bar._meta.get_field("a").remote_field.related_name
self.assertIsInstance(rel_name, str)
def test_abstract_model_pending_operations(self):
"""
Foreign key fields declared on abstract models should not add lazy
relations to resolve relationship declared as string (#24215).
"""
pending_ops_before = list(apps._pending_operations.items())
class AbstractForeignKeyModel(models.Model):
fk = models.ForeignKey("missing.FK", models.CASCADE)
class Meta:
abstract = True
self.assertIs(AbstractForeignKeyModel._meta.apps, apps)
self.assertEqual(
pending_ops_before,
list(apps._pending_operations.items()),
"Pending lookup added for a foreign key on an abstract model",
)
@isolate_apps("model_fields", "model_fields.tests")
def test_abstract_model_app_relative_foreign_key(self):
class AbstractReferent(models.Model):
reference = models.ForeignKey("Referred", on_delete=models.CASCADE)
class Meta:
app_label = "model_fields"
abstract = True
def assert_app_model_resolved(label):
class Referred(models.Model):
class Meta:
app_label = label
class ConcreteReferent(AbstractReferent):
class Meta:
app_label = label
self.assertEqual(
ConcreteReferent._meta.get_field("reference").related_model, Referred
)
assert_app_model_resolved("model_fields")
assert_app_model_resolved("tests")
@isolate_apps("model_fields")
def test_to_python(self):
class Foo(models.Model):
pass
class Bar(models.Model):
fk = models.ForeignKey(Foo, models.CASCADE)
self.assertEqual(Bar._meta.get_field("fk").to_python("1"), 1)
@isolate_apps("model_fields")
def test_fk_to_fk_get_col_output_field(self):
class Foo(models.Model):
pass
class Bar(models.Model):
foo = models.ForeignKey(Foo, models.CASCADE, primary_key=True)
class Baz(models.Model):
bar = models.ForeignKey(Bar, models.CASCADE, primary_key=True)
col = Baz._meta.get_field("bar").get_col("alias")
self.assertIs(col.output_field, Foo._meta.pk)
@isolate_apps("model_fields")
def test_recursive_fks_get_col(self):
class Foo(models.Model):
bar = models.ForeignKey("Bar", models.CASCADE, primary_key=True)
class Bar(models.Model):
foo = models.ForeignKey(Foo, models.CASCADE, primary_key=True)
with self.assertRaisesMessage(ValueError, "Cannot resolve output_field"):
Foo._meta.get_field("bar").get_col("alias")
@isolate_apps("model_fields")
def test_non_local_to_field(self):
class Parent(models.Model):
key = models.IntegerField(unique=True)
class Child(Parent):
pass
class Related(models.Model):
child = models.ForeignKey(Child, on_delete=models.CASCADE, to_field="key")
msg = (
"'model_fields.Related.child' refers to field 'key' which is not "
"local to model 'model_fields.Child'."
)
with self.assertRaisesMessage(FieldError, msg):
Related._meta.get_field("child").related_fields
def test_invalid_to_parameter(self):
msg = (
"ForeignKey(1) is invalid. First parameter to ForeignKey must be "
"either a model, a model name, or the string 'self'"
)
with self.assertRaisesMessage(TypeError, msg):
class MyModel(models.Model):
child = models.ForeignKey(1, models.CASCADE)
def test_manager_class_getitem(self):
self.assertIs(models.ForeignKey["Foo"], models.ForeignKey)
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