def METHOD_NAME(apps, schema_editor):
    # Populate the Rendition.filter field with Filter objects that match the spec in the
    # Rendition's filter_spec field
    Rendition = apps.get_model(app_name, rendition_model_name)
    Filter = apps.get_model("wagtailimages", "Filter")
    db_alias = schema_editor.connection.alias
    while True:
        # repeat this process until we've confirmed that no remaining renditions exist with
        # a null 'filter' field - this minimises the possibility of new ones being inserted
        # by active server processes while the query is in progress
        # Find all distinct filter_spec strings used by renditions with a null 'filter' field
        unmatched_filter_specs = (
            Rendition.objects.using(db_alias)
            .filter(filter__isnull=True)
            .values_list("filter_spec", flat=True)
            .distinct()
        )
        if not unmatched_filter_specs:
            break
        for filter_spec in unmatched_filter_specs:
            filter, _ = Filter.objects.using(db_alias).get_or_create(
                spec=filter_spec
            )
            Rendition.objects.using(db_alias).filter(
                filter_spec=filter_spec
            ).update(filter=filter)