迁移到 Django 3：使用 Field.choices 枚举类型 Aug 16, 2020 参考： https://adamj.eu/tech/2020/01/27/moving-to-django-3-field-choices-enumeration-types/ https://docs.djangoproject.com/en/3.1/releases/3.0/#enumerations-for-model-field-choices https://zhuanlan.zhihu.com/p/158611572