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
36350	Custom field's db_check() not taken into account when deciding whether to recreate constraint.	Baptiste Mispelon		"This is a regression introduced in 9953c804a9375956a542da94665662d306dff48d.

I have a custom field that implements `db_check()` in order to add a custom db constraint:
{{{#!python
class CharChoiceField(models.CharField):
    """"""
    A custom CharField that automatically creates a db constraint to guarante
    that the stored value respects the field's `choices`.
    """"""
    @property
    def non_db_attrs(self):
        # Remove `choices` from non_db_attrs so that migrations that only change
        # choices still trigger a db operation and drop/create the constraint.
        attrs = super().non_db_attrs
        return tuple({*attrs} - {""choices""})

    def db_check(self, connection):
        constraint = CheckConstraint(
            condition=Q(**{f""{self.name}__in"": dict(self.choices)}),
            name="""",  # doesn't matter, Django will reassign one anyway
        )
        with connection.schema_editor() as schema_editor:
            return constraint.get_check_sql(self.model, schema_editor)
}}}

This used to work well (in Django < 5.0): the constraint was added alongside the field when the initial migration was run, and any changes to the field's `choices` would trigger a new migration (that's standard Django behavior) which when executed would drop/create the constraint with the new value of `choices`.

However the commit I linked to at the beginning broke this: now any changes to `choices` still creates a migration, but executing the migration is now a no-op (which can be confirmed by checking with `sqlmigrate`).

I'm not sure if `Field.db_check()` can be considered public API (it's not documented), but I have a fix which is fairly simple (PR incoming) so I hope you'll consider it."	New feature	assigned	Database layer (models, ORM)	5.2	Normal			Balazs Endresz Mariusz Felisiak Simon Charette Lily Foote Carlton Gibson	Accepted	0	0	0	0	0	0