id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
26399	Migration refactoring - to facilitate third-party backend integration	Maximiliano Robaina	nobody	"I humbly think that django migration api need a some refactoring to facilitate third-party backend integration.

For instance, add_field method ![1], if I try to delete a default value on a column that does not have a previous default value definition I get an error on firebird, for which reason, I need to check if that field has got defined a default value before. Then I need to rewrite the whole add_field method too.

Maybe a possible approach would be to have sql templates (sql_alter_column_default, sql_alter_column_no_default, etc) as methods, instead of class attributes.

A disscusion about this en google groups
https://groups.google.com/forum/#!topicsearchin/django-developers/migrations$20firebird/django-developers/yZ0IWGT2qZQ

![1] https://github.com/django/django/blob/master/django/db/backends/base/schema.py#L373"	Uncategorized	new	Migrations	dev	Normal				Unreviewed	0	0	0	0	0	0