[Django] #34298: drop constraint if exists

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Django

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Jan 27, 2023, 5:33:49 AM1/27/23

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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.

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Ticket URL: <https://code.djangoproject.com/ticket/34298>
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Django

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Jan 27, 2023, 5:48:11 AM1/27/23

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#34298: drop constraint if exists
-------------------------------------+-------------------------------------
Reporter: sahaliyev | Owner: nobody

Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Changes (by Mariusz Felisiak):

* status: new => closed
* resolution: => wontfix

Comment:

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.