Change 435189 had a related patch set uploaded (by Pablo Grass (WMDE); owner: Pablo Grass (WMDE)):
[mediawiki/extensions/WikibaseLexeme@master] WIP Representation language: Prevent redundant lang

https://gerrit.wikimedia.org/r/435189

Discussed with @Lydia_Pintscher about challenges in validating on save-time, spiked a more snappy approach showing feedback while entering data...

@Lydia_Pintscher T195372 (the same problem for lemmas) was merged into this ticket. So is solving both problems now expected from this ticket here? Mind mending the title and maybe even adding a second BDD block?

I updated the description as discussed.

https://gerrit.wikimedia.org/r/#/c/435189/ representation part is ready for review
https://gerrit.wikimedia.org/r/#/c/436554/ lemma part is WIP

@Lydia_Pintscher

Lexeme lemmas and form representations use two rather different UX paradigms. This was the case already before this ticket was started but as we are now also dealing with validation and error messages we have to use one approach or the other.

• Lemmas offers you the save button to click while the form is invalid (e.g. a lemma w/o a term value) - validation is done on the server-side and only presented after receiving the answer (tooltip on the save button).
• Form representations disables (or at least tries to) the save button while the form is invalid - validation is done (partially) on the client and shown before the mistake is submitted.

The latter works well with the new approach of highlighting the invalid form field and indicating the problem already while the user is editing.
Applying the approach taken for representations to the lemmas would cause an inconsistency in how lemma (or header) errors are communicated to the user.

How do we proceed? There will be an inconsistency but we can transition away from it, the question is in which direction. In case of redundant lemma languages...

• keep the lemma widget's submit button enabled and show the error only when the user clicks? (accept the inconsistency between lemma and representation widget)
• disable the lemma widget's submit button? (accept the inconsistency inside lemma widget)

Remarks:

• Technically the first option would be easier
• Even when transitioning towards the "show errors immediately" generally we'd still need to maintain the capability to display post-submit errors because the frontend can only facilitate plausibility checks, backend errors can always still happen

Change 436800 had a related patch set (by Pablo Grass (WMDE)) published:
[mediawiki/extensions/WikibaseLexeme@master] Representation language: Pre-existing bind syntax

https://gerrit.wikimedia.org/r/436800

Change 436806 had a related patch set (by Pablo Grass (WMDE)) published:
[mediawiki/extensions/WikibaseLexeme@master] Representation language: Add aria-invalid

https://gerrit.wikimedia.org/r/436806

Change 435189 merged by jenkins-bot:
[mediawiki/extensions/WikibaseLexeme@master] Form representations: Prevent redundant langugages

https://gerrit.wikimedia.org/r/435189

Change 436800 merged by jenkins-bot:
[mediawiki/extensions/WikibaseLexeme@master] Representation language: Pre-existing bind syntax

https://gerrit.wikimedia.org/r/436800

Pablo and I just discussed this and to be consistent with all the other places we could find (Form representation, statements, term box) we should disable the Lemma widget's submit button when there is invalid input.

Change 436806 merged by jenkins-bot:
[mediawiki/extensions/WikibaseLexeme@master] Representation language: Add aria-invalid

https://gerrit.wikimedia.org/r/436806

The respective lemma ticket T195372 was reopened as dedicated challenge as it depends on some scaffolding yet to be created (T196342)

Ready for product review at e.g. https://wikidata.beta.wmflabs.org/w/index.php?title=Lexeme:L42#L42-F1