migrate id field from integer to biginter (probable bug)

[drakkan]

Hi,

I have two models like these:

class Allarme(models.Model):

....

class Registrazione(models.Model):

       allarme = models.ForeignKey(Allarme, blank=True, null=True, on_delete=models.DO_NOTHING, db_constraint=False)

       ....

now I want to change id field for these models from int to bigint so I added to both

id = models.BigAutoField(primary_key=True)

and I did the migration,

python manage.py sqlmigrate

show something like this:

BEGIN;

--

-- Alter field id on allarme

--

ALTER TABLE "multimedia_allarmi" ALTER COLUMN "id" TYPE bigint USING "id"::bigint;

DROP SEQUENCE IF EXISTS "multimedia_allarmi_id_seq" CASCADE;

CREATE SEQUENCE "multimedia_allarmi_id_seq";

ALTER TABLE "multimedia_allarmi" ALTER COLUMN "id" SET DEFAULT nextval('"multimedia_allarmi_id_seq"');

SELECT setval('"multimedia_allarmi_id_seq"', MAX("id")) FROM "multimedia_allarmi";

ALTER TABLE "multimedia_registrazioni" ALTER COLUMN "allarme_id" TYPE bigint USING "allarme_id"::bigint;

ALTER TABLE "multimedia_registrazioni" ADD CONSTRAINT "multimedia_registrazioni_allarme_id_4919213e_fk" FOREIGN KEY ("allarme_id") REFERENCES "multimedia_allarmi" ("id") DEFERRABLE INITIALLY DEFERRED;

--

-- Alter field id on registrazione

--

ALTER TABLE "multimedia_registrazioni" ALTER COLUMN "id" TYPE bigint USING "id"::bigint;

DROP SEQUENCE IF EXISTS "multimedia_registrazioni_id_seq" CASCADE;

CREATE SEQUENCE "multimedia_registrazioni_id_seq";

ALTER TABLE "multimedia_registrazioni" ALTER COLUMN "id" SET DEFAULT nextval('"multimedia_registrazioni_id_seq"');

SELECT setval('"multimedia_registrazioni_id_seq"', MAX("id")) FROM "multimedia_registrazioni";

COMMIT;

so as you can see a foreign key is added for a model field with db_constraint=False, 

can you please confirm that this is a bug? I'm using django 1.11.1

thanks!

[Tim Graham]

Yes, it looks like a bug.

The incorrect SQL is added here:

https://github.com/django/django/blob/8149bd00d8b8af816a683e5ecc0e204f344616f5/django/db/backends/base/schema.py#L745-L749

[Josh Schneier]

Opened a bug here: https://code.djangoproject.com/ticket/28298 and have a working patch here: https://github.com/django/django/pull/8628