drop constraint if exists

[sahaliyev]

Hi there,

Today encountered a problem, where Django migrate fails to drop constraint that actually does not exists.
Here is the scenario.
I created constraint via migration and then go to db and manually drop constraint and also changed my code.
Here, new migration file is generated to drop constraint, however, constraint already dropped.
In this case, migration is giving error.
It would be great just try to drop constraint and if not exists just pass.
As PostgreSQL has this functionality, drop constraint if exists.
Django can also use this.

[Mariusz Felisiak]

Thanks for this ticket, however when you mix manual changes to your database schema and Django migrations you do it at your own risk. You can always use the --fake option to mark a migration as already applied.

It would be great just try to drop constraint and if not exists just pass.

I disagree. The migrations framework should fail loudly when it encounters an unexpected database state.