#33736: Unable to sqlmigrate on an AlterUniqueTogether migration
-------------------------------------+-------------------------------------
Reporter: Noelia Marí | Owner: nobody
Salvador |
Type: Bug | Status: new
Component: Migrations | Version: 4.0
Severity: Normal | Resolution:
Keywords: sqlmigrate | Triage Stage:
| Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Description changed by Noelia Marí Salvador:
Old description:
> Reproduced in Django 4.0.4.
>
> Given this model:
> {{{
> class TestModel(models.Model):
> name = models.CharField(max_length=200)
> age = models.IntegerField()
> colour = models.CharField(max_length=200)
>
> class Meta:
> unique_together = ["name", "age"]
> }}}
>
> When migrations are created and applied, a unique constraint is created
> on the database. Now, we want to alter the unique_together to:
> `unique_together = ["name", "colour"]`
>
> After running `makemigrations`, **without applying the new migration**,
> we are able to run `sqlmigrate`:
> {{{
> $ testproject python3 manage.py sqlmigrate core 0003
> BEGIN;
> --
> -- Alter unique_together for testmodel (1 constraint(s))
> --
> DROP INDEX "core_testmodel_name_age_530d7841_uniq";
> CREATE UNIQUE INDEX "core_testmodel_name_colour_5002f5dd_uniq" ON
> "core_testmodel" ("name", "colour");
> COMMIT;
> }}}
>
> However, after we successfully apply migrations as below, `sqlmigrate`
> fails.
> {{{
> $ testproject python3 manage.py migrate
> Operations to perform:
> Apply all migrations: admin, auth, contenttypes, core, sessions
> Running migrations:
> Applying core.0003_alter_testmodel_unique_together... OK
> }}}
>
> So when running `sqlmigrate` on the same migration it crashes and throws
> a `ValueError` because it's looking for the prior index:
> {{{
> $ testproject python3 manage.py sqlmigrate core 0003
> Traceback (most recent call last):
> ...
> raise ValueError(
> ValueError: Found wrong number (0) of constraints for
> core_testmodel(name, age)
> }}}
New description:
Reproduced in Django 4.0.4.
Given this model:
{{{
class TestModel(models.Model):
name = models.CharField(max_length=200)
age = models.IntegerField()
colour = models.CharField(max_length=200)
class Meta:
unique_together = ["name", "age"]
}}}
When migrations are created and applied, a unique constraint is created on
the database. Now, we want to alter the unique_together to:
`unique_together = ["name", "colour"]`
After running `makemigrations`, **without applying the new migration**, we
are able to run `sqlmigrate`:
{{{
$ testproject python3 manage.py sqlmigrate core 0003
BEGIN;
--
-- Alter unique_together for testmodel (1 constraint(s))
--
DROP INDEX "core_testmodel_name_age_530d7841_uniq";
CREATE UNIQUE INDEX "core_testmodel_name_colour_5002f5dd_uniq" ON
"core_testmodel" ("name", "colour");
COMMIT;
}}}
However, after we successfully apply migrations as below, `sqlmigrate`
fails.
{{{
$ testproject python3 manage.py migrate
Operations to perform:
Apply all migrations: admin, auth, contenttypes, core, sessions
Running migrations:
Applying core.0003_alter_testmodel_unique_together... OK
}}}
So when running `sqlmigrate` on the same migration it crashes and throws a
`ValueError` because it's looking for the prior index:
{{{
$ testproject python3 manage.py sqlmigrate core 0003
Traceback (most recent call last):
...
raise ValueError(
ValueError: Found wrong number (0) of constraints for core_testmodel(name,
age)
}}}
Full minimal example can be found here:
https://github.com/AledWatkins/sqlmigrate-failures
--
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Ticket URL: <https://code.djangoproject.com/ticket/33736#comment:1>
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