#35761: When switching which field is `primary_key`, migrations do not seem to
handle multiple `auto` columns
-------------------------------------+-------------------------------------
Reporter: Jonas Vacek | Type: Bug
Status: new | Component: Database
| layer (models, ORM)
Version: 4.2 | Severity: Normal
Keywords: migrations, PK, | Triage Stage:
| Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
When there's a field that's defined as a primary key, switching to a
different field (or the default `id`) as the primary key does not work on
MySQL.
effectively, when going via the following states...
{{{
class MyModel(models.Model):
user_id = models.OneToOneField(primary_key=True)
other_field=models.CharField(...)
}}}
→
{{{
class MyModel(models.Model):
user_id = models.OneToOneField(primary_key=True)
id = models.BigIntegerField()
}}}
...generating this migration, and copying the values of `bad_key` to `id`
in the migration...
...and then swapping the primary_key separately...
{{{
class MyModel(models.Model):
user_id = models.OneToOneField()
id = models.AutoField(primary_key=True) # Removed after migrations
}}}
Generates the following migration operations (across two files, condensed
for brevity)
{{{
#1
migrations.AddField(
model_name="lookeruser",
name="id",
field=models.BigIntegerField(default=0),
),
#2
migrations.RunPython(move_pks_to_new_id),
# -- new file --
# 3
migrations.AlterField(
model_name="lookeruser",
name="id",
field=models.BigAutoField(auto_created=True, primary_key=True,
serialize=False, verbose_name="ID"),
),
# 4
migrations.AlterField(
model_name="lookeruser",
name="user_id",
field=models.OneToOneField(
help_text="The user on our platform.",
on_delete=django.db.models.deletion.CASCADE,
related_name="looker_user",
to=settings.AUTH_USER_MODEL,
),
),
}}}
This results in the following
{{{
E django.db.utils.OperationalError: (1075, 'Incorrect table
definition; there can be only one auto column and it must be defined as a
key')
}}}
Swapping the order of 3 and 4 does not seem to make a difference here,
they generate the following SQL for mysql:
{{{
--
-- Alter field id on lookeruser
--
ALTER TABLE `custom_reporting_lookeruser` MODIFY `id` bigint
AUTO_INCREMENT NOT NULL;
ALTER TABLE `custom_reporting_lookeruser` ADD CONSTRAINT
`custom_reporting_lookeruser_id_14e613d0_pk` PRIMARY KEY (`id`);
--
-- Alter field user on lookeruser
--
ALTER TABLE `custom_reporting_lookeruser` DROP FOREIGN KEY
`custom_reporting_lookeruser_user_id_d2546465_fk_auth_user_id`;
ALTER TABLE `custom_reporting_lookeruser` DROP PRIMARY KEY;
ALTER TABLE `custom_reporting_lookeruser` ADD CONSTRAINT
`custom_reporting_lookeruser_user_id_d2546465_uniq` UNIQUE (`user_id`);
ALTER TABLE `custom_reporting_lookeruser` ADD CONSTRAINT
`custom_reporting_lookeruser_user_id_d2546465_fk_auth_user_id` FOREIGN KEY
(`user_id`) REFERENCES `auth_user` (`id`);
}}}
I would have assumed this would be possible this usecase would have been
possible to achieve with the ORM, but I might be wrong..?
--
Ticket URL: <https://code.djangoproject.com/ticket/35761>
Django <https://code.djangoproject.com/>
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