Method database_backwards

django/db/migrations/operations/special.py:114–120

(self, app_label, schema_editor, from_state, to_state)

            self._run_sql(schema_editor, self.sql)

    def database_backwards(self, app_label, schema_editor, from_state, to_state):
        if self.reverse_sql is None:
            raise NotImplementedError("You cannot reverse this operation")
        if router.allow_migrate(
            schema_editor.connection.alias, app_label, **self.hints
        ):
            self._run_sql(schema_editor, self.reverse_sql)

    def describe(self):
        return "Raw SQL operation"