Python django.db.migrations 模块，RemoveField() 实例源码

def test_remove_field(self):
        project_state = self.set_up_test_model()
        operation = migrations.RemoveField('Pony', 'pink')
        new_state = project_state.clone()
        operation.state_forwards('tests', new_state)
        self.assertColumnExists('tests_pony', 'pink')
        with connection.schema_editor() as editor:
            operation.database_forwards('tests', editor, project_state, new_state)
        self.assertColumnNotExists('tests_pony', 'pink')
        with connection.schema_editor() as editor:
            operation.database_backwards('tests', editor, new_state, project_state)
        self.assertColumnExists('tests_pony', 'pink')

def test_remove_foreign_key_field(self):
        project_state = self.set_up_test_model()
        operation = migrations.RemoveField('Rider', 'pony')
        new_state = project_state.clone()
        operation.state_forwards('tests', new_state)
        self.assertColumnExists('tests_rider', 'pony_id')
        with connection.schema_editor() as editor:
            operation.database_forwards('tests', editor, project_state, new_state)
        self.assertColumnNotExists('tests_rider', 'pony_id')
        with connection.schema_editor() as editor:
            operation.database_backwards('tests', editor, new_state, project_state)
        self.assertColumnExists('tests_rider', 'pony_id')

def remove_field(field, filters: List[str]):
    """Removes the specified field from a model.

    Arguments:
        field:
            The field to remove from a model.

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

    model = define_fake_model({'title': field})
    project = migrations.state.ProjectState.from_apps(apps)

    with connection.schema_editor() as schema_editor:
        execute_migration(schema_editor, [
            migrations.CreateModel(
                model.__name__,
                fields=[
                    ('title', field.clone())
                ]
            )
        ], project)

    with filtered_schema_editor(*filters) as (schema_editor, calls):
        execute_migration(schema_editor, [
            migrations.RemoveField(
                model.__name__,
                'title'
            )
        ], project)

    yield calls