[Koha] MARC frameworks in Koha

[Marcel de Rooy]

Hi developers or librarians,

If you are interested in say sorting search results or lists by publication date based on 260 and RDA 264, please read further.
OR If you use varying kohafield mappings across your MARC frameworks. Say you connected biblio.copyrightdate to 260$c in framework A, but to 264$c in framework B.

Bug 10306 (https://bugs.koha-community.org/bugzilla3/show_bug.cgi?id=10306) is aimed to resolve the issue of having the copyrightdate in two MARC fields.
It allows you to have multiple mappings per kohafield. So you can connect 260c and 264c to copyrightdate. Current Koha allowed you to add the second mapping already in the frameworks, but it silently ignores one of the two.

In finishing this development however, I got stuck at the following question: Should Koha really allow varying kohafield mappings per framework? In the above example the multiple mappings feature should resolve the need of having a different assignment for copyrightdate between framework A and B. Both could simply have two mappings for copyrightdate.
Although Koha more or less allows you to add kohafield assignments per framework via the MARC frameworks, it does not really support kohafields per framework. (The Koha to MARC mappings tool in Administration does change the mappings in Default and copies them to other frameworks.) We have GetMarcFromKohaField calls in the codebase that do not pass a framework code. And when we process search results or import records, we do not have a framework code either. So in those cases Koha just uses the kohafield mappings from the Default framework, although you might have specified another mapping in the associated framework of a search result.

I would propose now to make the decision that we only use one set of kohafield mappings (those from Default), and that we do no longer allow changes to kohafield mappings in the other frameworks.
The possibility of adding multiple mappings per kohafield hopefully removes most objections to that approach as illustrated in the frameworks A and B example.

I submitted my changes so far on the Bugzilla report. If we agree on Default as the authoritative framework for these mappings, I will still add code to change GetMarcFromKohaField calls etc.

If you have stringent reasons for maintaining varying kohafield mappings per framework and your need for them cannot be resolved with multiple mappings, please respond and provide information about the fields you are mapping differently across your frameworks.

Any other feedback is welcome too.

Thanks,

Marcel