How is one supposed to recover from a failed migration in South?

Question

I'm using South (version 0.6, the one packaged in Ubuntu Lucid Lynx) to manage database migrations in Django, and currently using SQLite as a back end. I came across a situation where I generated a migration to add a column with:

./manage.py startmigration myapp --auto added_new_column

... which generated a migration that looked sensible. However, when I then applied the migration with:

./manage.py migrate myapp

I got an error because the column I was adding was non-NULL, but I hadn't specified a default value:

ValueError: You cannot add a null=False column without a default value.

What is one supposed to do if a migration fails in this way, and you want to go back and regenerate it? (What I did in practice, namely to delete the migration and generate a new one, has created several further problems.) Perhaps I've missed something obvious in the documentation about this...

Answer 1

In this case, migration failed and didn't get written into db, so you can safely remove old one and create again. Also you can try using newer south version, i believe they added default check for NOT NULL fields on creating step.