Changing value type (for example int -> datetime.timedelta) does not invalidate value, stored in database

[PeterBeklemishev]

Describe the problem

Changing value type (for example int -> datetime.timedelta) does not invalidate value, stored in database

Steps to reproduce

• Create constance_config entry with int value
• Modify value via admin interface
• Change default value in config to datetime.timedelta instance
• Try to get this value via costance.<OUR_KEY_NAME> - it will return int instead of timedelta

System configuration

• Django version: 2.0.x
• Python version: 3.5

[sergei-iurchenko]

Django datamigrations for next version of project solve this issues. There is no robust way to migrate data between different types automatically.