id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
35422	Migration crash when renaming a field referenced in GeneratedField.expression	Sarah Boyce	Mariusz Felisiak	"Given a model (migrated) on SQLite
{{{
class Foo(models.Model):
    name = models.CharField(max_length=10)
    lower_name = models.GeneratedField(
        expression=Lower(""name""),
        output_field=models.CharField(max_length=10),
        db_persist=True,
    )
}}}
when you update to
{{{
class Foo(models.Model):
    surname = models.CharField(max_length=10)
    lower_name = models.GeneratedField(
        expression=Lower(""surname""),
        output_field=models.CharField(max_length=10),
        db_persist=True,
    )
}}}
and makemigrations, you then get asked `Was foo.name renamed to foo.surname (a CharField)? [y/N]` and say `y` (because it was)
You then get a crash when migrating:


{{{
Operations to perform:
  Apply all migrations: app3
Running migrations:
  Applying app3.0005_rename_name_foo_surname_alter_foo_lower_name...Traceback (most recent call last):
  File ""path_to_project\mysite\manage.py"", line 22, in <module>
    main()
  File ""path_to_project\mysite\manage.py"", line 18, in main
    execute_from_command_line(sys.argv)
  File ""path_to_project\venv\Lib\site-packages\django\core\management\__init__.py"", line 442, in execute_from_command_line
    utility.execute()
  File ""path_to_project\venv\Lib\site-packages\django\core\management\__init__.py"", line 436, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File ""path_to_project\venv\Lib\site-packages\django\core\management\base.py"", line 413, in run_from_argv
    self.execute(*args, **cmd_options)
  File ""path_to_project\venv\Lib\site-packages\django\core\management\base.py"", line 459, in execute
    output = self.handle(*args, **options)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File ""path_to_project\venv\Lib\site-packages\django\core\management\base.py"", line 107, in wrapper
    res = handle_func(*args, **kwargs)
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File ""path_to_project\venv\Lib\site-packages\django\core\management\commands\migrate.py"", line 356, in handle
    post_migrate_state = executor.migrate(
                         ^^^^^^^^^^^^^^^^^
  File ""path_to_project\venv\Lib\site-packages\django\db\migrations\executor.py"", line 135, in migrate
    state = self._migrate_all_forwards(
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File ""path_to_project\venv\Lib\site-packages\django\db\migrations\executor.py"", line 167, in _migrate_all_forwards
    state = self.apply_migration(
            ^^^^^^^^^^^^^^^^^^^^^
  File ""path_to_project\venv\Lib\site-packages\django\db\migrations\executor.py"", line 255, in apply_migration
    state = migration.apply(state, schema_editor)
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File ""path_to_project\venv\Lib\site-packages\django\db\migrations\migration.py"", line 132, in apply
    operation.database_forwards(
  File ""path_to_project\venv\Lib\site-packages\django\db\migrations\operations\fields.py"", line 241, in database_forwards
    schema_editor.alter_field(from_model, from_field, to_field)
  File ""path_to_project\venv\Lib\site-packages\django\db\backends\base\schema.py"", line 875, in alter_field
    or old_field.generated_sql(self.connection)
       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File ""path_to_project\venv\Lib\site-packages\django\db\models\fields\generated.py"", line 58, in generated_sql
    resolved_expression = self.expression.resolve_expression(
                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File ""path_to_project\venv\Lib\site-packages\django\db\models\expressions.py"", line 1052, in resolve_expression
    c.source_expressions[pos] = arg.resolve_expression(
                                ^^^^^^^^^^^^^^^^^^^^^^^
  File ""path_to_project\venv\Lib\site-packages\django\db\models\expressions.py"", line 874, in resolve_expression
    return query.resolve_ref(self.name, allow_joins, reuse, summarize)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File ""path_to_project\venv\Lib\site-packages\django\db\models\sql\query.py"", line 2010, in resolve_ref
    join_info = self.setup_joins(
                ^^^^^^^^^^^^^^^^^
  File ""path_to_project\venv\Lib\site-packages\django\db\models\sql\query.py"", line 1863, in setup_joins
    path, final_field, targets, rest = self.names_to_path(
                                       ^^^^^^^^^^^^^^^^^^^
  File ""path_to_project\venv\Lib\site-packages\django\db\models\sql\query.py"", line 1768, in names_to_path
    raise FieldError(
django.core.exceptions.FieldError: Cannot resolve keyword 'name' into field. Choices are: id, lower_name, surname
}}}"	Bug	closed	Migrations	5.0	Release blocker	fixed		Simon Charette Mariusz Felisiak Lily Foote David Sanders Bhuvnesh	Ready for checkin	1	0	0	0	0	0