Fix support for adding and removing relationships in relationship-only fields in the submission

[artlowel]

References

• Fixes Most relation fields (except Author) do not display their relations in the Submission form. #1094
• Depends on Repeatable fields with look up still broken in some cases #1092
• Requires Patch Add entire array with virtual values does not work DSpace#3224

Description

This PR will auto update the item input in the submission form when the item changes. That way, when a relationship is added the form will update.

It will also fix an issue where the lookup button wasn't shown for repeatable relationship only fields, when they already had a value

Instructions for Reviewers

You can test this PR by verifying that relationships can be added and removed regardless of whether they're for a mixed field.

This PR seems bigger than it is, because it depends on #1092 You can see only the changes in this PR here

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[benbosman]

I've tested this PR, and it seems to solve the remaining issues which were not yet handled in #1092

Using the PR, our standard test configs are functional again

[tdonohue]

@artlowel : Overall this works & fixes #1094 for me as well.

That said, a few bugs I'm noticing:

1. The field "hint" appears seems to be duplicated under any relation. See below screenshot.
   
2. Clicking the delete/trash button next to a current selection doesn't appear to fully work. Sometimes the item in the form remains (e.g. on the Journal Issue form, I cannot seem to delete a selected volume). However, sometimes it appears to work (e.g. on the Person form. I can delete the Publication) but if I click the Lookup button again, I see it's still selected in the popup. (I haven't dug into this deeply, it might be a backend issue or an issue with the deletion request to the backend.)
3. For single-valued fields, if you change the selected entity in the Lookup modal, it keeps adding new values to the list on the form. See this screenshot where it appears I have 3 Volumes linked to this new Issue. All I did was open the Lookup modal, select one volume. Close the modal. Open it again, change the selection. Close it. Open it a third time, change the selection and close it. The Submission Form thinks I now have 3 values, but it's just one relationship that has been changed 3 times. If I open the Lookup modal though, I see it only has one current selection.
   

Overall, the behavior here is much improved! The basics work. So, if one of these is difficult to solve quickly, we could leave it as a "known issue" for now. I just wanted to make sure these bugs were documented somewhere.

[artlowel]

@tdonohue

The first issue should be fixed now.

Issues 2 and 3 are symptoms of the same problem as far as I can tell: the DELETE request for those relationships fails. Rest returns a 400 with the message "Request is invalid or incorrect". It's a fairly straightforward request, the authorization and CSRF headers look to be correct. The relationship to be deleted also definitely still exists, you can still GET it afterwards. So this looks to be a problem on the REST side.

[tdonohue]

👍 Thanks @artlowel . I re-tested today and it looks good now.

Somewhat strangely, today the delete button appears to be working correctly for me. I also had Chrome DevTools open and I see the DELETE request succeeds. I'm not sure why it wasn't working yesterday.

I will note though that after clicking the DELETE button, I see the deleted value disappear from the Submission Form, but it's still "cached" in the Lookup window (if I click Lookup it still appears selected there even though the DELETE command to REST succeeded, returning a 204). This is not a significant bug to block this PR, but it's something we may wish to look into further during Testathon. I can log it separately. UPDATE: logged it as #1101

In any case, this looks good to me now.