Firebird - Schema migrations: add or alter field

[Maximiliano Robaina]

Hi folks,

I'm here again trying to up to date the django-firebird backend.

The last stable version was for django 1.8 LTS, that came to end of life, so I want to update to 1.11 LTS first  and then to 2.0.

Having said that, one of unresolved things is about  adding a non-nullable field to a populated table, in this case Firebird seems to work differently than others sql engines. 

If I have to update data over a recently added field (actually django does this adding a default value and removing this afterward), I need commit the alter table command first then, populate the new field with the provide default value. [1]

Firebird doesn't allow updates/inserts to use objects created in the same transaction (in this case the column) because DDL is actually only really executed/completed at transaction commit.

Then, What do you think is the best approach to achieve this?

Is necessary to rewrite the context maneger interface of BaseDatabaseSchemaEditor?

Maybe a new hook to run command after the metadata update finish?

Regards.

[1] Here there's a discussion about this

https://groups.yahoo.com/neo/groups/firebird-support/conversations/topics/130739