See code changes in pull request #3011 submitted by derat.

Sounds cool, to me, derat. 😁👍

I've got some working code to do this. I'll upload it soon to get early feedback on whether the approach that I'm taking (mostly constrained to root/static/scripts/relationship-editor/components/RelationshipDialogContent.js) is acceptable.

I've gotten tired enough of clicking the "Change direction" button (or forgetting to, and making groups be members of people) that I'm starting to look at implementing this.

My feeling is that the link direction in the relationship editor should be updated to make sense (if possible) whenever the user changes the link type or selects a target entity.

Specifically, when a relationship of one of the following types is being added between a person and a group (including a choir or an orchestra), I think that the person should default to being on the source side:

• member of / members
• conductor for / conductor
• founded / founded by
• collaborator on / collaborators
• composer-in-residence at / composers-in-residence
• artistic director for / artistic director

It might make sense to also add similar handling for "voice of / voiced by" relationships between people and characters, but that's a far less common case.

I don't plan to actually restrict anything; I just want the link direction to default to what's most likely to be correct. Editors will still be able to reverse it if needed (e.g. maybe they have an open edit to modify one or both of the artists' types).

Does that sound reasonable?

Maybe it would be more easy for developpers to :

BLOCK edit which tries to make group IS A MEMBER OF person. by going back to edit form with error (like when an edit changes nothing or does bad thing, which is exactly the case here).

Same for support and many others.

The decision was more how to do it, UI-wise; you may be right it shouldn't be DR, but I'm not sure.

The question, as I understood it, was: when do we trigger the automatic direction-switching, and how do we alert the user that it's happened? I think the answer is: it should be triggered at the earliest time when the relationship type is known (so, for add relationship, when it's selected from the dropdown, or immediately when the page is seeded with a type; for edit relationship, at page load and when selections change); obviously if the type is changed away from a person<->group rel (or to one that should be in a different direction) the button should come back to usability. I think the direction should not be changed (back) when the button comes back, when applicable. I'd propose that the user be alerted as though it's a form error, underneath the type/entity selector; these alerts should happen whenever the order is changed without direct input. Obviously nothing should happen if the artist types cannot be determined or don't match the "one person, one group" paradigm.

This doesn't seem to require a decision - there's no question that it would be useful to do this, if possible.

Yeah, I've had a look at this and there doesn't seem to be enough data in the edit/relationship page to make it work at the moment. We would need to pass or look up the artist information somehow.

It would also need a JS function to check the relationship type and set the entity order and disable the change direction button whenever the select box was changed.

Not much I can do here, so unassigning.

I'll work on implementing this in the UI as soon as I get enough time to do it.