[Django] #35199: Makemigrations raises KeyError when removing a field from Meta.unique_together when its a list

[Django]

#35199: Makemigrations raises KeyError when removing a field from
Meta.unique_together when its a list
-------------------------------------+-------------------------------------
Reporter: Paco | Owner: nobody
Martínez |
Type: Bug | Status: new
Component: | Version: 4.2
Migrations | Keywords: migrations,
Severity: Normal | unique_together, makemigrations
Triage Stage: | Has patch: 0
Unreviewed |
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
-------------------------------------+-------------------------------------
Having a model like this, with a **unique_together** with a **list of
lists**:

{{{
from django.db import models

class MyModel(models.Model):
field1 = models.CharField(max_length=50)
field2 = models.IntegerField()
field3 = models.DateField()

class Meta:
unique_together=[['field1', 'field2', 'field3']]
}}}


If we want to remove one of the fields from the constraint like:

{{{
class Meta:
unique_together=[['field1', 'field2']]
}}}

When we run the ''makemigrations'' command, it raises a KeyError. This is
the traceback:
{{{
Traceback (most recent call last):
File "/code/manage.py", line 26, in <module>
main()
File "/code/manage.py", line 22, in main
execute_from_command_line(sys.argv)
File "/usr/local/lib/python3.12/site-
packages/django/core/management/__init__.py", line 442, in
execute_from_command_line
utility.execute()
File "/usr/local/lib/python3.12/site-
packages/django/core/management/__init__.py", line 436, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File "/usr/local/lib/python3.12/site-
packages/django/core/management/base.py", line 412, in run_from_argv
self.execute(*args, **cmd_options)
File "/usr/local/lib/python3.12/site-
packages/django/core/management/base.py", line 458, in execute
output = self.handle(*args, **options)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.12/site-
packages/django/core/management/base.py", line 106, in wrapper
res = handle_func(*args, **kwargs)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.12/site-
packages/django/core/management/commands/makemigrations.py", line 233, in
handle
changes = autodetector.changes(
^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.12/site-
packages/django/db/migrations/autodetector.py", line 46, in changes
changes = self._detect_changes(convert_apps, graph)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.12/site-
packages/django/db/migrations/autodetector.py", line 192, in
_detect_changes
self.generate_removed_altered_unique_together()
File "/usr/local/lib/python3.12/site-
packages/django/db/migrations/autodetector.py", line 1506, in
generate_removed_altered_unique_together
self._generate_removed_altered_foo_together(operations.AlterUniqueTogether)
File "/usr/local/lib/python3.12/site-
packages/django/db/migrations/autodetector.py", line 1481, in
_generate_removed_altered_foo_together
for (
File "/usr/local/lib/python3.12/site-
packages/django/db/migrations/autodetector.py", line 1462, in
_get_altered_foo_together_operations
field = new_model_state.get_field(field_name)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.12/site-
packages/django/db/migrations/state.py", line 765, in get_field
return self.fields[field_name]
~~~~~~~~~~~^^^^^^^^^^^^
KeyError: 'field1'

}}}

This does NOT happen when the unique_together option is a **tuple**. It
works as expected creating the migration.
--
Ticket URL: <https://code.djangoproject.com/ticket/35199>
Django <https://code.djangoproject.com/>
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[Django]

#35199: Makemigrations raises KeyError when removing a field from
Meta.unique_together when its a list
-------------------------------------+-------------------------------------

Reporter: Paco Martínez | Owner: nobody
Type: Bug | Status: closed
Component: Migrations | Version: 4.2
Severity: Normal | Resolution: invalid
Keywords: migrations, | Triage Stage:
unique_together, makemigrations | Unreviewed
Has patch: 0 | Needs documentation: 0

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

Changes (by Paco Martínez):

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


Old description:

New description:

Having a model like this, with a **unique_together** with a **list of
lists**:

{{{
from django.db import models

class MyModel(models.Model):
field1 = models.CharField(max_length=50)

field2 = models.ForeignKey()
field3 = models.ForeignKey()

Comment:

Sorry but trying a bit more I discovered that the fields in the
unique_together were named with the "_id" suffix as they are
ForeignKeyFields. Don't know how the constraint is there for several
months and working fine. Now it's enforcing to name the fields without the
suffix.

With that the makemigrations command runs as expected.

Sorry for the inconvenience of creating the ticket.
--
Ticket URL: <https://code.djangoproject.com/ticket/35199#comment:1>