Maniphest T171937

Historical visual diff broken for revision deletions
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Description

Steps to reproduce:

Visit a diff which has been deleted, eg. https://de.wikipedia.beta.wmflabs.org/w/index.php?title=Benutzer:Schnark&diff=2074&oldid=1945&visualdiff=1
Switch to visual diff.
If you have the right to view the deleted diff, do so.
Switch to visual diff again.

Actual result:
The visual diff fails to load in both cases, and just shows the loading bar.

Expected result:
When you are not allowed to view the diff, the switch widget should either don't exist at all, be disabled, or don't do anything except telling you that you can't view the diff.
I don't know whether it is possible to show visual diffs for deleted revisions you have the right to view. If it is possible, then the diff should be shown, if RESTbase isn't able to do so, the switcher should be disabled for such diffs.

Details

	Subject	Repo	Branch	Lines +/-
	Handle errors when fetching revisions for visual diffs	mediawiki/extensions/VisualEditor	master	+8 -0

Customize query in gerrit

Related Objects
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Status	Assigned	Task
Open	None	T105173 HTML diffs of edits for everything
Resolved	None	T167508 Visual diff: Make VE visual diffs available for historical diffs via MediaWiki's DiffView page
Resolved	matmarex	T171937 Historical visual diff broken for revision deletions

Event Timeline

Schnark created this task.Jul 28 2017, 8:56 AM

Restricted Application added a project: VisualEditor. · View Herald TranscriptJul 28 2017, 8:56 AM

Restricted Application added a subscriber: Aklapper. · View Herald Transcript

• Deskana triaged this task as Medium priority.Jul 28 2017, 2:13 PM

• Deskana moved this task from To Triage to TR6: Visual diffs on the VisualEditor board.

• Deskana added a project: MediaWiki-Revision-deletion.

• Deskana set the point value for this task to 1.Aug 22 2017, 2:24 PM

• Deskana renamed this task from Visual diff broken for revision deletions to Historical visual diff broken for revision deletions.Jan 16 2018, 4:55 PM

• marcella moved this task from TR6: Visual diffs to Bug Fixes on the VisualEditor board.Nov 13 2018, 6:58 PM

• marcella removed the point value for this task.Dec 13 2018, 4:52 PM

• marcella added a parent task: T167508: Visual diff: Make VE visual diffs available for historical diffs via MediaWiki's DiffView page.

• marcella moved this task from Bug Fixes to Freezer on the VisualEditor board.Dec 13 2018, 4:56 PM

Three years later, the issue is still persisting.

Change 666236 had a related patch set uploaded (by Bartosz Dziewoński; owner: Bartosz Dziewoński):
[mediawiki/extensions/VisualEditor@master] Handle errors when fetching revisions for visual diffs

https://gerrit.wikimedia.org/r/666236

gerritbot added a project: Patch-For-Review.Feb 23 2021, 12:28 AM

Change 666236 merged by jenkins-bot:
[mediawiki/extensions/VisualEditor@master] Handle errors when fetching revisions for visual diffs

https://gerrit.wikimedia.org/r/666236

ReleaseTaggerBot added a project: MW-1.36-notes (1.36.0-wmf.33; 2021-03-02).Feb 24 2021, 6:00 PM

Maintenance_bot removed a project: Patch-For-Review.Feb 24 2021, 6:11 PM

That is a very minimal fix – it will just hide the loading bar and display an error message when appropriate.

Parsoid (and RESTBase) do not currently allow fetching deleted revisions, even for users who are allowed to view them in MediaWiki. I'm hoping that will be improved some day, at which point our visual diffs should magically start working as well. For now, showing that it's impossible is the best we can do.

matmarex added a project: Editing-team (Kanban Board).Feb 24 2021, 6:51 PM

matmarex moved this task from Incoming to Ready for Sign Off on the Editing-team (Kanban Board) board.

matmarex added a project: Skipped QA.

• ppelberg closed this task as Resolved.Mar 3 2021, 3:13 AM

matmarex mentioned this in T337817: Don't show Visual diff switcher for diff of suppressed revisions.May 31 2023, 9:20 PM