Method test_alter_fk_to_o2o

tests/schema/tests.py:1895–1938

#24163 - Tests altering of ForeignKey to OneToOneField

(self)

    @skipUnlessDBFeature("supports_foreign_keys", "can_introspect_foreign_keys")
    def test_alter_fk_to_o2o(self):
        """
        #24163 - Tests altering of ForeignKey to OneToOneField
        """
        # Create the table
        with connection.schema_editor() as editor:
            editor.create_model(Author)
            editor.create_model(Book)
        # Ensure the field is right to begin with
        columns = self.column_classes(Book)
        self.assertEqual(
            columns["author_id"][0],
            connection.features.introspected_field_types["BigIntegerField"],
        )
        # Ensure the field is not unique
        author = Author.objects.create(name="Joe")
        Book.objects.create(
            author=author, title="Django 1", pub_date=datetime.datetime.now()
        )
        Book.objects.create(
            author=author, title="Django 2", pub_date=datetime.datetime.now()
        )
        Book.objects.all().delete()
        self.assertForeignKeyExists(Book, "author_id", "schema_author")
        # Alter the ForeignKey to OneToOneField
        old_field = Book._meta.get_field("author")
        new_field = OneToOneField(Author, CASCADE)
        new_field.set_attributes_from_name("author")
        with connection.schema_editor() as editor:
            editor.alter_field(Book, old_field, new_field, strict=True)
        columns = self.column_classes(BookWithO2O)
        self.assertEqual(
            columns["author_id"][0],
            connection.features.introspected_field_types["BigIntegerField"],
        )
        # Ensure the field is unique now
        BookWithO2O.objects.create(
            author=author, title="Django 1", pub_date=datetime.datetime.now()
        )
        with self.assertRaises(IntegrityError):
            BookWithO2O.objects.create(
                author=author, title="Django 2", pub_date=datetime.datetime.now()
            )
        self.assertForeignKeyExists(BookWithO2O, "author_id", "schema_author")

    def test_alter_field_fk_to_o2o(self):
        with connection.schema_editor() as editor: