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

def test_alter_unique_together(self):
        project_state = self.set_up_test_model()
        operation = migrations.AlterUniqueTogether('Pony', [('pink', 'weight')])
        new_state = project_state.clone()
        operation.state_forwards('tests', new_state)

        @all_schemata
        def insert(cursor, **kwargs):
            cursor.execute('INSERT INTO tests_pony (pink, weight) VALUES (1, 1)')
            cursor.execute('INSERT INTO tests_pony (pink, weight) VALUES (1, 1)')
            cursor.execute('DELETE FROM tests_pony')

        @all_schemata
        def insert_fail(cursor, **kwargs):
            cursor.execute('INSERT INTO tests_pony (pink, weight) VALUES (1, 1)')
            with self.assertRaises(IntegrityError):
                with atomic():
                    cursor.execute('INSERT INTO tests_pony (pink, weight) VALUES (1, 1)')
            cursor.execute('DELETE FROM tests_pony')

        with connection.cursor() as cursor:
            insert(cursor)
            with connection.schema_editor() as editor:
                operation.database_forwards('tests', editor, project_state, new_state)
            insert_fail(cursor)
            with connection.schema_editor() as editor:
                operation.database_backwards('tests', editor, new_state, project_state)
            insert(cursor)