Python django.db.migrations.AlterField() Examples

def get_migrations_for_django_21_and_newer():
    return [
        # remove primary key information from 'key' field
        migrations.AlterField(
            model_name='resetpasswordtoken',
            name='key',
            field=models.CharField(db_index=True, primary_key=False, max_length=64, unique=True, verbose_name='Key'),
        ),
        # add a new id field
        migrations.AddField(
            model_name='resetpasswordtoken',
            name='id',
            field=models.AutoField(primary_key=True, serialize=False),
            preserve_default=False,
        ),
        migrations.RunPython(
            populate_auto_incrementing_pk_field,
            migrations.RunPython.noop
        ),
    ] 

def test_hstore_autodetect_required():
    """Tests whether changes in the `required` option are properly detected by
    the auto detector."""

    before = [
        migrations.state.ModelState(
            "tests", "Model1", [("title", HStoreField())]
        )
    ]
    after = [
        migrations.state.ModelState(
            "tests", "Model1", [("title", HStoreField(required=["en"]))]
        )
    ]

    changes = _detect_changes(before, after)

    _assert_autodetector(
        changes,
        [
            migrations.AlterField(
                "Model1", "title", HStoreField(required=["en"])
            )
        ],
    ) 

def test_optimize_through_fields(self):
        """
        field-level through checking is working. This should manage to collapse
        model Foo to nonexistence, and model Bar to a single IntegerField
        called "width".
        """
        self.assertOptimizesTo(
            [
                migrations.CreateModel("Foo", [("name", models.CharField(max_length=255))]),
                migrations.CreateModel("Bar", [("size", models.IntegerField())]),
                migrations.AddField("Foo", "age", models.IntegerField()),
                migrations.AddField("Bar", "width", models.IntegerField()),
                migrations.AlterField("Foo", "age", models.IntegerField()),
                migrations.RenameField("Bar", "size", "dimensions"),
                migrations.RemoveField("Foo", "age"),
                migrations.RenameModel("Foo", "Phou"),
                migrations.RemoveField("Bar", "dimensions"),
                migrations.RenameModel("Phou", "Fou"),
                migrations.DeleteModel("Fou"),
            ],
            [
                migrations.CreateModel("Bar", [("width", models.IntegerField())]),
            ],
        ) 

def test_alter_field_rename_field(self):
        """
        RenameField should optimize to the other side of AlterField,
        and into itself.
        """
        self.assertOptimizesTo(
            [
                migrations.AlterField("Foo", "name", models.CharField(max_length=255)),
                migrations.RenameField("Foo", "name", "title"),
                migrations.RenameField("Foo", "title", "nom"),
            ],
            [
                migrations.RenameField("Foo", "name", "nom"),
                migrations.AlterField("Foo", "nom", models.CharField(max_length=255)),
            ],
        ) 

def test_alter_geom_field_dim(self):
        Neighborhood = self.current_state.apps.get_model('gis', 'Neighborhood')
        p1 = Polygon(((0, 0), (0, 1), (1, 1), (1, 0), (0, 0)))
        Neighborhood.objects.create(name='TestDim', geom=MultiPolygon(p1, p1))
        # Add 3rd dimension.
        self.alter_gis_model(
            migrations.AlterField, 'Neighborhood', 'geom', False,
            fields.MultiPolygonField, field_class_kwargs={'srid': 4326, 'dim': 3}
        )
        self.assertTrue(Neighborhood.objects.first().geom.hasz)
        # Rewind to 2 dimensions.
        self.alter_gis_model(
            migrations.AlterField, 'Neighborhood', 'geom', False,
            fields.MultiPolygonField, field_class_kwargs={'srid': 4326, 'dim': 2}
        )
        self.assertFalse(Neighborhood.objects.first().geom.hasz) 

def test_alter_fk_non_fk(self):
        """
        Altering an FK to a non-FK works (#23244)
        """
        # Test the state alteration
        operation = migrations.AlterField(
            model_name="Rider",
            name="pony",
            field=models.FloatField(),
        )
        project_state, new_state = self.make_test_state("test_afknfk", operation, related_model=True)
        # Test the database alteration
        self.assertColumnExists("test_afknfk_rider", "pony_id")
        self.assertColumnNotExists("test_afknfk_rider", "pony")
        with connection.schema_editor() as editor:
            operation.database_forwards("test_afknfk", editor, project_state, new_state)
        self.assertColumnExists("test_afknfk_rider", "pony")
        self.assertColumnNotExists("test_afknfk_rider", "pony_id")
        # And test reversal
        with connection.schema_editor() as editor:
            operation.database_backwards("test_afknfk", editor, new_state, project_state)
        self.assertColumnExists("test_afknfk_rider", "pony_id")
        self.assertColumnNotExists("test_afknfk_rider", "pony") 

def test_alter_field_m2m(self):
        project_state = self.set_up_test_model("test_alflmm", second_model=True)

        project_state = self.apply_operations("test_alflmm", project_state, operations=[
            migrations.AddField("Pony", "stables", models.ManyToManyField("Stable", related_name="ponies"))
        ])
        Pony = project_state.apps.get_model("test_alflmm", "Pony")
        self.assertFalse(Pony._meta.get_field('stables').blank)

        project_state = self.apply_operations("test_alflmm", project_state, operations=[
            migrations.AlterField(
                "Pony", "stables", models.ManyToManyField(to="Stable", related_name="ponies", blank=True)
            )
        ])
        Pony = project_state.apps.get_model("test_alflmm", "Pony")
        self.assertTrue(Pony._meta.get_field('stables').blank) 

def test_alter_field_with_index(self):
        """
        Test AlterField operation with an index to ensure indexes created via
        Meta.indexes don't get dropped with sqlite3 remake.
        """
        project_state = self.set_up_test_model("test_alflin", index=True)
        operation = migrations.AlterField("Pony", "pink", models.IntegerField(null=True))
        new_state = project_state.clone()
        operation.state_forwards("test_alflin", new_state)
        # Test the database alteration
        self.assertColumnNotNull("test_alflin_pony", "pink")
        with connection.schema_editor() as editor:
            operation.database_forwards("test_alflin", editor, project_state, new_state)
        # Index hasn't been dropped
        self.assertIndexExists("test_alflin_pony", ["pink"])
        # And test reversal
        with connection.schema_editor() as editor:
            operation.database_backwards("test_alflin", editor, new_state, project_state)
        # Ensure the index is still there
        self.assertIndexExists("test_alflin_pony", ["pink"]) 

def test_rename_field_reloads_state_on_fk_target_changes(self):
        """
        If RenameField doesn't reload state appropriately, the AlterField
        crashes on MySQL due to not dropping the PonyRider.pony foreign key
        constraint before modifying the column.
        """
        app_label = 'alter_rename_field_reloads_state_on_fk_target_changes'
        project_state = self.apply_operations(app_label, ProjectState(), operations=[
            migrations.CreateModel('Rider', fields=[
                ('id', models.CharField(primary_key=True, max_length=100)),
            ]),
            migrations.CreateModel('Pony', fields=[
                ('id', models.CharField(primary_key=True, max_length=100)),
                ('rider', models.ForeignKey('%s.Rider' % app_label, models.CASCADE)),
            ]),
            migrations.CreateModel('PonyRider', fields=[
                ('id', models.AutoField(primary_key=True)),
                ('pony', models.ForeignKey('%s.Pony' % app_label, models.CASCADE)),
            ]),
        ])
        project_state = self.apply_operations(app_label, project_state, operations=[
            migrations.RenameField('Rider', 'id', 'id2'),
            migrations.AlterField('Pony', 'id', models.CharField(primary_key=True, max_length=99)),
        ], atomic=connection.features.supports_atomic_references_rename) 

def test_alter_field_reloads_state_on_fk_target_changes(self):
        """
        If AlterField doesn't reload state appropriately, the second AlterField
        crashes on MySQL due to not dropping the PonyRider.pony foreign key
        constraint before modifying the column.
        """
        app_label = 'alter_alter_field_reloads_state_on_fk_target_changes'
        project_state = self.apply_operations(app_label, ProjectState(), operations=[
            migrations.CreateModel('Rider', fields=[
                ('id', models.CharField(primary_key=True, max_length=100)),
            ]),
            migrations.CreateModel('Pony', fields=[
                ('id', models.CharField(primary_key=True, max_length=100)),
                ('rider', models.ForeignKey('%s.Rider' % app_label, models.CASCADE)),
            ]),
            migrations.CreateModel('PonyRider', fields=[
                ('id', models.AutoField(primary_key=True)),
                ('pony', models.ForeignKey('%s.Pony' % app_label, models.CASCADE)),
            ]),
        ])
        project_state = self.apply_operations(app_label, project_state, operations=[
            migrations.AlterField('Rider', 'id', models.CharField(primary_key=True, max_length=99)),
            migrations.AlterField('Pony', 'id', models.CharField(primary_key=True, max_length=99)),
        ]) 

def test_alter_field_pk(self):
        """
        Tests the AlterField operation on primary keys (for things like PostgreSQL's SERIAL weirdness)
        """
        project_state = self.set_up_test_model("test_alflpk")
        # Test the state alteration
        operation = migrations.AlterField("Pony", "id", models.IntegerField(primary_key=True))
        new_state = project_state.clone()
        operation.state_forwards("test_alflpk", new_state)
        self.assertIsInstance(project_state.models["test_alflpk", "pony"].get_field_by_name("id"), models.AutoField)
        self.assertIsInstance(new_state.models["test_alflpk", "pony"].get_field_by_name("id"), models.IntegerField)
        # Test the database alteration
        with connection.schema_editor() as editor:
            operation.database_forwards("test_alflpk", editor, project_state, new_state)
        # And test reversal
        with connection.schema_editor() as editor:
            operation.database_backwards("test_alflpk", editor, new_state, project_state) 

def test_alter_field_pk(self):
        """
        Tests the AlterField operation on primary keys (for things like PostgreSQL's SERIAL weirdness)
        """
        project_state = self.set_up_test_model("test_alflpk")
        # Test the state alteration
        operation = migrations.AlterField("Pony", "id", models.IntegerField(primary_key=True))
        new_state = project_state.clone()
        operation.state_forwards("test_alflpk", new_state)
        self.assertIsInstance(project_state.models["test_alflpk", "pony"].get_field_by_name("id"), models.AutoField)
        self.assertIsInstance(new_state.models["test_alflpk", "pony"].get_field_by_name("id"), models.IntegerField)
        # Test the database alteration
        with connection.schema_editor() as editor:
            operation.database_forwards("test_alflpk", editor, project_state, new_state)
        # And test reversal
        with connection.schema_editor() as editor:
            operation.database_backwards("test_alflpk", editor, new_state, project_state) 

def test_repoint_field_m2m(self):
        project_state = self.set_up_test_model("test_alflmm", second_model=True, third_model=True)

        project_state = self.apply_operations("test_alflmm", project_state, operations=[
            migrations.AddField("Pony", "places", models.ManyToManyField("Stable", related_name="ponies"))
        ])
        Pony = project_state.apps.get_model("test_alflmm", "Pony")

        project_state = self.apply_operations("test_alflmm", project_state, operations=[
            migrations.AlterField("Pony", "places", models.ManyToManyField(to="Van", related_name="ponies"))
        ])

        # Ensure the new field actually works
        Pony = project_state.apps.get_model("test_alflmm", "Pony")
        p = Pony.objects.create(pink=False, weight=4.55)
        p.places.create()
        self.assertEqual(p.places.count(), 1)
        p.places.all().delete() 

def test_optimize_through_fields(self):
        """
        field-level through checking is working. This should manage to collapse
        model Foo to nonexistence, and model Bar to a single IntegerField
        called "width".
        """
        self.assertOptimizesTo(
            [
                migrations.CreateModel("Foo", [("name", models.CharField(max_length=255))]),
                migrations.CreateModel("Bar", [("size", models.IntegerField())]),
                migrations.AddField("Foo", "age", models.IntegerField()),
                migrations.AddField("Bar", "width", models.IntegerField()),
                migrations.AlterField("Foo", "age", models.IntegerField()),
                migrations.RenameField("Bar", "size", "dimensions"),
                migrations.RemoveField("Foo", "age"),
                migrations.RenameModel("Foo", "Phou"),
                migrations.RemoveField("Bar", "dimensions"),
                migrations.RenameModel("Phou", "Fou"),
                migrations.DeleteModel("Fou"),
            ],
            [
                migrations.CreateModel("Bar", [("width", models.IntegerField())]),
            ],
        ) 

def test_alter_field_reloads_state_on_fk_target_changes(self):
        """
        If AlterField doesn't reload state appropriately, the second AlterField
        crashes on MySQL due to not dropping the PonyRider.pony foreign key
        constraint before modifying the column.
        """
        app_label = 'alter_alter_field_reloads_state_on_fk_target_changes'
        project_state = self.apply_operations(app_label, ProjectState(), operations=[
            migrations.CreateModel('Rider', fields=[
                ('id', models.CharField(primary_key=True, max_length=100)),
            ]),
            migrations.CreateModel('Pony', fields=[
                ('id', models.CharField(primary_key=True, max_length=100)),
                ('rider', models.ForeignKey('%s.Rider' % app_label, models.CASCADE)),
            ]),
            migrations.CreateModel('PonyRider', fields=[
                ('id', models.AutoField(primary_key=True)),
                ('pony', models.ForeignKey('%s.Pony' % app_label, models.CASCADE)),
            ]),
        ])
        project_state = self.apply_operations(app_label, project_state, operations=[
            migrations.AlterField('Rider', 'id', models.CharField(primary_key=True, max_length=99)),
            migrations.AlterField('Pony', 'id', models.CharField(primary_key=True, max_length=99)),
        ]) 

def test_alter_field_rename_field(self):
        """
        RenameField should optimize to the other side of AlterField,
        and into itself.
        """
        self.assertOptimizesTo(
            [
                migrations.AlterField("Foo", "name", models.CharField(max_length=255)),
                migrations.RenameField("Foo", "name", "title"),
                migrations.RenameField("Foo", "title", "nom"),
            ],
            [
                migrations.RenameField("Foo", "name", "nom"),
                migrations.AlterField("Foo", "nom", models.CharField(max_length=255)),
            ],
        ) 

def test_alter_fk_non_fk(self):
        """
        Altering an FK to a non-FK works (#23244)
        """
        # Test the state alteration
        operation = migrations.AlterField(
            model_name="Rider",
            name="pony",
            field=models.FloatField(),
        )
        project_state, new_state = self.make_test_state("test_afknfk", operation, related_model=True)
        # Test the database alteration
        self.assertColumnExists("test_afknfk_rider", "pony_id")
        self.assertColumnNotExists("test_afknfk_rider", "pony")
        with connection.schema_editor() as editor:
            operation.database_forwards("test_afknfk", editor, project_state, new_state)
        self.assertColumnExists("test_afknfk_rider", "pony")
        self.assertColumnNotExists("test_afknfk_rider", "pony_id")
        # And test reversal
        with connection.schema_editor() as editor:
            operation.database_backwards("test_afknfk", editor, new_state, project_state)
        self.assertColumnExists("test_afknfk_rider", "pony_id")
        self.assertColumnNotExists("test_afknfk_rider", "pony") 

def test_alter_field_with_index(self):
        """
        Test AlterField operation with an index to ensure indexes created via
        Meta.indexes don't get dropped with sqlite3 remake.
        """
        project_state = self.set_up_test_model("test_alflin", index=True)
        operation = migrations.AlterField("Pony", "pink", models.IntegerField(null=True))
        new_state = project_state.clone()
        operation.state_forwards("test_alflin", new_state)
        # Test the database alteration
        self.assertColumnNotNull("test_alflin_pony", "pink")
        with connection.schema_editor() as editor:
            operation.database_forwards("test_alflin", editor, project_state, new_state)
        # Index hasn't been dropped
        self.assertIndexExists("test_alflin_pony", ["pink"])
        # And test reversal
        with connection.schema_editor() as editor:
            operation.database_backwards("test_alflin", editor, new_state, project_state)
        # Ensure the index is still there
        self.assertIndexExists("test_alflin_pony", ["pink"]) 

def test_alter_field_with_index(self):
        """
        Test AlterField operation with an index to ensure indexes created via
        Meta.indexes don't get dropped with sqlite3 remake.
        """
        project_state = self.set_up_test_model("test_alflin", index=True)
        operation = migrations.AlterField("Pony", "pink", models.IntegerField(null=True))
        new_state = project_state.clone()
        operation.state_forwards("test_alflin", new_state)
        # Test the database alteration
        self.assertColumnNotNull("test_alflin_pony", "pink")
        with connection.schema_editor() as editor:
            operation.database_forwards("test_alflin", editor, project_state, new_state)
        # Index hasn't been dropped
        self.assertIndexExists("test_alflin_pony", ["pink"])
        # And test reversal
        with connection.schema_editor() as editor:
            operation.database_backwards("test_alflin", editor, new_state, project_state)
        # Ensure the index is still there
        self.assertIndexExists("test_alflin_pony", ["pink"]) 

def test_alter_field_pk(self):
        """
        Tests the AlterField operation on primary keys (for things like PostgreSQL's SERIAL weirdness)
        """
        project_state = self.set_up_test_model("test_alflpk")
        # Test the state alteration
        operation = migrations.AlterField("Pony", "id", models.IntegerField(primary_key=True))
        new_state = project_state.clone()
        operation.state_forwards("test_alflpk", new_state)
        self.assertIsInstance(project_state.models["test_alflpk", "pony"].get_field_by_name("id"), models.AutoField)
        self.assertIsInstance(new_state.models["test_alflpk", "pony"].get_field_by_name("id"), models.IntegerField)
        # Test the database alteration
        with connection.schema_editor() as editor:
            operation.database_forwards("test_alflpk", editor, project_state, new_state)
        # And test reversal
        with connection.schema_editor() as editor:
            operation.database_backwards("test_alflpk", editor, new_state, project_state) 

def test_hstore_autodetect_uniqueness():
    """Tests whether changes in the `uniqueness` option are properly detected
    by the auto detector."""

    before = [
        migrations.state.ModelState(
            "tests", "Model1", [("title", HStoreField())]
        )
    ]
    after = [
        migrations.state.ModelState(
            "tests", "Model1", [("title", HStoreField(uniqueness=["en"]))]
        )
    ]

    changes = _detect_changes(before, after)

    _assert_autodetector(
        changes,
        [
            migrations.AlterField(
                "Model1", "title", HStoreField(uniqueness=["en"])
            )
        ],
    ) 

def test_repoint_field_m2m(self):
        project_state = self.set_up_test_model("test_alflmm", second_model=True, third_model=True)

        project_state = self.apply_operations("test_alflmm", project_state, operations=[
            migrations.AddField("Pony", "places", models.ManyToManyField("Stable", related_name="ponies"))
        ])
        Pony = project_state.apps.get_model("test_alflmm", "Pony")

        project_state = self.apply_operations("test_alflmm", project_state, operations=[
            migrations.AlterField("Pony", "places", models.ManyToManyField(to="Van", related_name="ponies"))
        ])

        # Ensure the new field actually works
        Pony = project_state.apps.get_model("test_alflmm", "Pony")
        p = Pony.objects.create(pink=False, weight=4.55)
        p.places.create()
        self.assertEqual(p.places.count(), 1)
        p.places.all().delete() 

def get_operations():
    """
    This will break things if you upgrade Django to 1.8 having already applied this migration in 1.7.
    Since this is for a demo site it doesn't really matter (simply blow away the DB if you want to go to 1.8)

    Our demo site is a unusual in that we want to run it's tests (for integration testing) in multiple Django versions.
    Typical sites don't have to worry about that sort of thing.
    """
    compatible = (1, 8) <= DJANGO_VERSION < (1, 10)
    if not compatible:
        return []

    return [
        migrations.AlterField(
            model_name='user',
            name='groups',
            field=models.ManyToManyField(related_query_name='user', related_name='user_set', to='auth.Group', blank=True, help_text='The groups this user belongs to. A user will get all permissions granted to each of their groups.', verbose_name='groups'),
        ),
        migrations.AlterField(
            model_name='user',
            name='last_login',
            field=models.DateTimeField(null=True, verbose_name='last login', blank=True),
        ),
    ] 

def test_optimize_through_fields(self):
        """
        field-level through checking is working. This should manage to collapse
        model Foo to nonexistence, and model Bar to a single IntegerField
        called "width".
        """
        self.assertOptimizesTo(
            [
                migrations.CreateModel("Foo", [("name", models.CharField(max_length=255))]),
                migrations.CreateModel("Bar", [("size", models.IntegerField())]),
                migrations.AddField("Foo", "age", models.IntegerField()),
                migrations.AddField("Bar", "width", models.IntegerField()),
                migrations.AlterField("Foo", "age", models.IntegerField()),
                migrations.RenameField("Bar", "size", "dimensions"),
                migrations.RemoveField("Foo", "age"),
                migrations.RenameModel("Foo", "Phou"),
                migrations.RemoveField("Bar", "dimensions"),
                migrations.RenameModel("Phou", "Fou"),
                migrations.DeleteModel("Fou"),
            ],
            [
                migrations.CreateModel("Bar", [("width", models.IntegerField())]),
            ],
        ) 

def test_alter_fk_non_fk(self):
        """
        Altering an FK to a non-FK works (#23244)
        """
        # Test the state alteration
        operation = migrations.AlterField(
            model_name="Rider",
            name="pony",
            field=models.FloatField(),
        )
        project_state, new_state = self.make_test_state("test_afknfk", operation, related_model=True)
        # Test the database alteration
        self.assertColumnExists("test_afknfk_rider", "pony_id")
        self.assertColumnNotExists("test_afknfk_rider", "pony")
        with connection.schema_editor() as editor:
            operation.database_forwards("test_afknfk", editor, project_state, new_state)
        self.assertColumnExists("test_afknfk_rider", "pony")
        self.assertColumnNotExists("test_afknfk_rider", "pony_id")
        # And test reversal
        with connection.schema_editor() as editor:
            operation.database_backwards("test_afknfk", editor, new_state, project_state)
        self.assertColumnExists("test_afknfk_rider", "pony_id")
        self.assertColumnNotExists("test_afknfk_rider", "pony") 

def test_alter_geom_field_dim(self):
        Neighborhood = self.current_state.apps.get_model('gis', 'Neighborhood')
        p1 = Polygon(((0, 0), (0, 1), (1, 1), (1, 0), (0, 0)))
        Neighborhood.objects.create(name='TestDim', geom=MultiPolygon(p1, p1))
        # Add 3rd dimension.
        self.alter_gis_model(
            migrations.AlterField, 'Neighborhood', 'geom', False,
            fields.MultiPolygonField, field_class_kwargs={'srid': 4326, 'dim': 3}
        )
        self.assertTrue(Neighborhood.objects.first().geom.hasz)
        # Rewind to 2 dimensions.
        self.alter_gis_model(
            migrations.AlterField, 'Neighborhood', 'geom', False,
            fields.MultiPolygonField, field_class_kwargs={'srid': 4326, 'dim': 2}
        )
        self.assertFalse(Neighborhood.objects.first().geom.hasz) 

def test_alter_field_rename_field(self):
        """
        RenameField should optimize to the other side of AlterField,
        and into itself.
        """
        self.assertOptimizesTo(
            [
                migrations.AlterField("Foo", "name", models.CharField(max_length=255)),
                migrations.RenameField("Foo", "name", "title"),
                migrations.RenameField("Foo", "title", "nom"),
            ],
            [
                migrations.RenameField("Foo", "name", "nom"),
                migrations.AlterField("Foo", "nom", models.CharField(max_length=255)),
            ],
        ) 

def migrate_data(apps, schema_editor):
    # SQLite does not support altering constraints. However, we use it for tests only, and there's no data to migrate.
    if schema_editor.connection.vendor == 'sqlite':
        return

    def _sql_add_cascading_user_constraint(model_name, field_name):
        return f'ALTER TABLE desecapi_{model_name}' \
               f' ADD CONSTRAINT desecapi_{model_name}_{field_name}_id_update_cascade' \
               f' FOREIGN KEY (`{field_name}_id`) REFERENCES `desecapi_user` (`id`) ON UPDATE CASCADE'

    def _sql_drop_cascading_user_constraint(model_name, field_name):
        return f'ALTER TABLE desecapi_{model_name} DROP CONSTRAINT desecapi_{model_name}_{field_name}_id_update_cascade'

    # Add cascading foreign key constraints.
    # This has to be done after removing the regular constraints using migrations.AlterField. If done the other
    # way around, AlterField will drop the cascading constraint.
    schema_editor.execute(_sql_add_cascading_user_constraint('domain', 'owner')),
    schema_editor.execute(_sql_add_cascading_user_constraint('token', 'user')),

    # Repopulate user ID fields
    User = apps.get_model('desecapi', 'User')
    with transaction.atomic():
        for user in User.objects.all():
            User.objects.filter(email=user.email).update(id=uuid.uuid4().hex)

    # Remove cascading foreign key constraints
    schema_editor.execute(_sql_drop_cascading_user_constraint('domain', 'owner')),
    schema_editor.execute(_sql_drop_cascading_user_constraint('token', 'user')), 

def test_alter_field_reloads_state_on_fk_with_to_field_target_changes(self):
        """
        If AlterField doesn't reload state appropriately, the second AlterField
        crashes on MySQL due to not dropping the PonyRider.pony foreign key
        constraint before modifying the column.
        """
        app_label = 'alter_alter_field_reloads_state_on_fk_with_to_field_target_changes'
        project_state = self.apply_operations(app_label, ProjectState(), operations=[
            migrations.CreateModel('Rider', fields=[
                ('id', models.CharField(primary_key=True, max_length=100)),
                ('slug', models.CharField(unique=True, max_length=100)),
            ]),
            migrations.CreateModel('Pony', fields=[
                ('id', models.CharField(primary_key=True, max_length=100)),
                ('rider', models.ForeignKey('%s.Rider' % app_label, models.CASCADE, to_field='slug')),
                ('slug', models.CharField(unique=True, max_length=100)),
            ]),
            migrations.CreateModel('PonyRider', fields=[
                ('id', models.AutoField(primary_key=True)),
                ('pony', models.ForeignKey('%s.Pony' % app_label, models.CASCADE, to_field='slug')),
            ]),
        ])
        project_state = self.apply_operations(app_label, project_state, operations=[
            migrations.AlterField('Rider', 'slug', models.CharField(unique=True, max_length=99)),
            migrations.AlterField('Pony', 'slug', models.CharField(unique=True, max_length=99)),
        ]) 

def alter_field(old_field, new_field, filters: List[str]):
    """Alters a field from one state to the other.

    Arguments:
        old_field:
            The field before altering it.

        new_field:
            The field after altering it.

        filters:
            List of strings to filter
            SQL statements on.
    """

    model = define_fake_model({"title": old_field})
    state = migrations.state.ProjectState.from_apps(apps)

    apply_migration(
        [
            migrations.CreateModel(
                model.__name__, fields=[("title", old_field.clone())]
            )
        ],
        state,
    )

    with filtered_schema_editor(*filters) as calls:
        apply_migration(
            [migrations.AlterField(model.__name__, "title", new_field)], state
        )

    yield calls