Question

In every generated migration files by South manage.py schemamigration, there usually will be a subclass of the south.v2.SchemaMigration. The class would contain forwards() and backwards() methods and also models attribute. How does South use the models attribute?

Answer 1

This is called ORM freezing.

We also use a human-readable format that’s easy to change; since South relies on the frozen models not only for reacreating the ORM but also for detecting changes, it’s really useful to be able to edit them now and again (and also serves as a valuable debugging tool if you attach failing migrations to a ticket).

http://south.aeracode.org/docs/ormfreezing.html