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
37477	makemigrations orders AlterModelOptions before RenameModel when a new model has an FK to the renamed model	Akshat Gupta		"{{{#!text
When a model is renamed, `makemigrations` can put operations on the new model name before the `RenameModel` operation. `migrate` then crashes with a `KeyError`.

It needs three things in one `makemigrations` run:

1. A model is renamed (and the rename prompt is answered ""y"").
2. Its Meta options change, for example `ordering`.
3. A new model with a ForeignKey to the renamed model is added.

Starting point (migrated):
}}}

{{{#!python
class Author(models.Model):
    name = models.CharField(max_length=50)
}}}

{{{#!text
Changed to:
}}}

{{{#!python
class Writer(models.Model):
    name = models.CharField(max_length=50)

    class Meta:
        ordering = [""name""]


class Book(models.Model):
    title = models.CharField(max_length=50)
    writer = models.ForeignKey(Writer, on_delete=models.CASCADE)
}}}

{{{#!text
`makemigrations` (""Was the model shop.Author renamed to Writer? y"") writes the operations in this order:
}}}

{{{#!python
operations = [
    migrations.AlterModelOptions(name=""writer"", options={""ordering"": [""name""]}),
    migrations.RenameModel(old_name=""Author"", new_name=""Writer""),
    migrations.CreateModel(name=""Book"", ...),
]
}}}

{{{#!text
`migrate` fails:

    File "".../django/db/migrations/state.py"", line 183, in alter_model_options
        model_state = self.models[app_label, model_name]
    KeyError: ('shop', 'writer')

Without the new `Book` model the order is correct. I also see `AddIndex` and `AddConstraint` on the renamed model emitted before `RenameModel` in the same situation.

Cause: `generate_renamed_models()` gives `RenameModel` dependencies for the reverse relations of the renamed model. A new model with an FK to it makes `RenameModel` depend on that `CreateModel`. The options, index and constraint operations on the renamed model have no dependency on `RenameModel`. `_sort_migrations()` emits operations without dependencies first, so they end up before the rename.

A fix could make every operation on a renamed model depend on its `RenameModel` in `_sort_migrations()`. I tried this locally and the migrations tests pass.

Tested on main (6.2 dev) with SQLite.
}}}
"	Bug	new	Migrations	dev	Normal		autodetector, RenameModel	Akshat Gupta	Unreviewed	0	0	0	0	0	0