[Django] #36364: Migration executor cannot handle AlterField operation on ForeignObject

[Django]

#36364: Migration executor cannot handle AlterField operation on ForeignObject
-------------------------------------+-------------------------------------
Reporter: Jacob Walls | Type: Bug
Status: new | Component:
| Migrations
Version: dev | Severity: Release
| blocker
Keywords: composite primary | Triage Stage:
key | Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Starting with the four models in the composite primary key docs, altering
the model with `ForeignObject` to become a `ForeignKey` (while also
changing the related model to no longer use a composite primary key),
produces a migration that cannot run. Failure is similar to #35992 and
#35997.

To reproduce:
- Copy the four models from the
[https://docs.djangoproject.com/en/5.2/topics/composite-primary-key
/#composite-primary-keys docs]
- makemigrations
- Use new models:

{{{
class Product(models.Model):
name = models.CharField(max_length=100)


class Order(models.Model):
reference = models.CharField(max_length=20, primary_key=True)


class OrderLineItem(models.Model):
product = models.ForeignKey(Product, on_delete=models.CASCADE)
order = models.ForeignKey(Order, on_delete=models.CASCADE,
primary_key=True)
quantity = models.IntegerField()


class Foo(models.Model):
item_order_id = models.IntegerField()
item_product_id = models.CharField(max_length=20)
item = models.ForeignKey(
OrderLineItem,
on_delete=models.CASCADE,
)
}}}

- makemigrations
- migrate

{{{
Running migrations:
Applying models.12009_order_product_orderlineitem_foo... OK
Applying
models.12010_remove_orderlineitem_pk_alter_foo_item_and_more...Traceback
(most recent call last):
File "/Users/<user>/prj/arches/manage.py", line 27, in <module>
execute_from_command_line(sys.argv)
~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^
File "/Users/<user>/django/django/core/management/__init__.py", line
442, in execute_from_command_line
utility.execute()
~~~~~~~~~~~~~~~^^
File "/Users/<user>/django/django/core/management/__init__.py", line
436, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^
File "/Users/<user>/django/django/core/management/base.py", line 416, in
run_from_argv
self.execute(*args, **cmd_options)
~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^
File "/Users/<user>/django/django/core/management/base.py", line 460, in
execute
output = self.handle(*args, **options)
File "/Users/<user>/django/django/core/management/base.py", line 107, in
wrapper
res = handle_func(*args, **kwargs)
File "/Users/<user>/django/django/core/management/commands/migrate.py",
line 353, in handle
post_migrate_state = executor.migrate(
targets,
...<3 lines>...
fake_initial=fake_initial,
)
File "/Users/<user>/django/django/db/migrations/executor.py", line 135,
in migrate
state = self._migrate_all_forwards(
state, plan, full_plan, fake=fake, fake_initial=fake_initial
)
File "/Users/<user>/django/django/db/migrations/executor.py", line 167,
in _migrate_all_forwards
state = self.apply_migration(
state, migration, fake=fake, fake_initial=fake_initial
)
File "/Users/<user>/django/django/db/migrations/executor.py", line 255,
in apply_migration
state = migration.apply(state, schema_editor)
File "/Users/<user>/django/django/db/migrations/migration.py", line 132,
in apply
operation.database_forwards(
~~~~~~~~~~~~~~~~~~~~~~~~~~~^
self.app_label, schema_editor, old_state, project_state
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
)
^
File "/Users/<user>/django/django/db/migrations/operations/fields.py",
line 236, in database_forwards
schema_editor.alter_field(from_model, from_field, to_field)
~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/Users/<user>/django/django/db/backends/base/schema.py", line 848,
in alter_field
if not self._field_should_be_altered(old_field, new_field):
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^
File "/Users/<user>/django/django/db/backends/base/schema.py", line
1690, in _field_should_be_altered
return self.quote_name(old_field.column) != self.quote_name(
~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^
File "/Users/<user>/django/django/db/backends/base/schema.py", line 207,
in quote_name
return self.connection.ops.quote_name(name)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^
File "/Users/<user>/django/django/db/backends/postgresql/operations.py",
line 197, in quote_name
if name.startswith('"') and name.endswith('"'):
^^^^^^^^^^^^^^^
AttributeError: 'NoneType' object has no attribute 'startswith'
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/36364>
Django <https://code.djangoproject.com/>
The Web framework for perfectionists with deadlines.

[Django]

#36364: Migration executor cannot handle AlterField operation on ForeignObject
-------------------------------------+-------------------------------------

Reporter: Jacob Walls | Owner: (none)

Type: Bug | Status: new
Component: Migrations | Version: dev

Severity: Normal | Resolution:

Keywords: composite primary | Triage Stage:
key | Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Changes (by Jacob Walls):

* severity: Release blocker => Normal

Comment:

Setting back to Normal, realized we have this disclaimer:

> Django doesn’t support migrating to, or from, a composite primary key
after the table is created.

Perhaps this is an "optimization" ticket then.
--
Ticket URL: <https://code.djangoproject.com/ticket/36364#comment:1>

[Django]

#36364: Migration executor cannot handle AlterField operation on ForeignObject
-------------------------------------+-------------------------------------
Reporter: Jacob Walls | Owner: (none)
Type: Bug | Status: new
Component: Migrations | Version: dev
Severity: Normal | Resolution:
Keywords: composite primary | Triage Stage:
key | Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Comment (by Jacob Walls):

Just chiming in to add that, as I mentioned, this is reproducible without
"migrating from a composite primary key" but rather migrating away from
the `ForeignObject`. E.g., making this single change from

{{{
item = models.ForeignObject(
OrderLineItem,
on_delete=models.CASCADE,
from_fields=("item_order_id", "item_product_id"),
to_fields=("order_id", "product_id"),
)
}}}

to
{{{
item = models.IntegerField()
}}}

reproduces the issue.
--
Ticket URL: <https://code.djangoproject.com/ticket/36364#comment:2>

[Django]

#36364: Migration executor cannot handle AlterField operation on ForeignObject
-------------------------------------+-------------------------------------
Reporter: Jacob Walls | Owner: (none)
Type: Bug | Status: new
Component: Migrations | Version: dev
Severity: Normal | Resolution:

Keywords: composite primary | Triage Stage: Accepted
key |

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

Changes (by Sarah Boyce):

* stage: Unreviewed => Accepted

Comment:

Thank you! Feels a little similar to #34820
--
Ticket URL: <https://code.djangoproject.com/ticket/36364#comment:3>

[Django]

#36364: Migration executor cannot handle AlterField operation on ForeignObject
-------------------------------------+-------------------------------------

Reporter: Jacob Walls | Owner: Ahmed
| Nassar
Type: Bug | Status: assigned

Component: Migrations | Version: dev
Severity: Normal | Resolution:
Keywords: composite primary | Triage Stage: Accepted
key |
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Changes (by Ahmed Nassar):

* owner: (none) => Ahmed Nassar
* status: new => assigned

--
Ticket URL: <https://code.djangoproject.com/ticket/36364#comment:4>

[Django]

#36364: Migration executor cannot handle AlterField operation on ForeignObject
-------------------------------------+-------------------------------------
Reporter: Jacob Walls | Owner:

| JaeHyuckSa

Type: Bug | Status: assigned
Component: Migrations | Version: dev
Severity: Normal | Resolution:

Keywords: CompositePrimaryKey | Triage Stage: Accepted

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

Changes (by JaeHyuckSa):

* owner: Ahmed Nassar => JaeHyuckSa

--
Ticket URL: <https://code.djangoproject.com/ticket/36364#comment:6>

[Django]

#36364: Migration executor cannot handle AlterField operation on ForeignObject
-------------------------------------+-------------------------------------
Reporter: Jacob Walls | Owner:
| JaeHyuckSa
Type: Bug | Status: assigned
Component: Migrations | Version: dev
Severity: Normal | Resolution:
Keywords: CompositePrimaryKey | Triage Stage: Accepted

Has patch: 1 | Needs documentation: 0

Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Changes (by JaeHyuckSa):

* has_patch: 0 => 1

--
Ticket URL: <https://code.djangoproject.com/ticket/36364#comment:7>