... coming from a file system, from a database with no id_run, position, tag_index columns, having one component or more...
Create a role defining get_X methods, where X is id_run, position, tag_index, subset, inherit from this role in both parent chack and result object.
See handling of this problem in #493 in npg_qc_viewer/root/src/ui_checks/rna_seqc.tt2