I have a question. In my software there is a table “employees”. This has several “hasMany” associations in which there is a “date_from”. I need now from the table always the association, which fit to a certain date. eg: The date is “2020-01-05” there are associated records with “2020-01-01” and one with “2020-02-01”. The associated record should now be only the one with the date “2020-01-01”, since that is valid on that date. I can’t solve it via a “finder” now, I thought of a “mapper”.Problem: I can only call it separately and not register it in the “finder”. The “mapReducer” always changes the structure (that’s what it’s for), but I can’t register a “normal mapper” in the “finder”. The question now is, is there some kind of “best practice” to solve such a relatively trivial problem? I am thankful for any answer.