如何通过ORM在关系数据库中表示代数数据类型？

Question

下面是我用来解析字符串并将结果存储到Python数据结构中的语法.

;; subject_code is a string which matches certain pattern.

code => <subject_code>

prereq => one_of | normal | and | either_or

one_of => “one of” code*

normal => code*

and => prereq “and/plus” prereq

either_or => “either” prereq “or” prereq

代码在这里.

如何通过django ORM将prereq存储到关系数据库中？

我已经浏览了django的文档,但我还没有得到线索.

提前致谢.