def METHOD_NAME(self, db, db_field, request):
    """
    For each related field (foreign key) which has object-level permissions
    narrow result to objects for which user has permissions.
    """
    queryset = super().METHOD_NAME(db, db_field, request)
    related_model = db_field.rel.to
    if issubclass(related_model, PermissionsForObjectMixin):
        queryset = related_model._get_objects_for_user(
            request.user, queryset
        )
    return queryset