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Item has label conflict with itself
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Description

I'm using Addwiki with my bot to update incorrect values for P2397. Now I'm getting for a few items a strange error. The label of the item has a conflict with the item itself.
While trying to update Q80958 I get the following response from the API:

{"error":{"code":"modification-failed","info":"Item [[Q80958|Q80958]] already has label \"\u05d1\u05d5\u05d8\u05e4\u05d5\u05d2\u05d5\" associated with language code he, using the same description text.","messages":[{"name":"wikibase-validator-label-with-description-conflict","parameters":["\u05d1\u05d5\u05d8\u05e4\u05d5\u05d2\u05d5","he","[[Q80958|Q80958]]"],"html":{"*":"Item Q80958 already has label \"\u05d1\u05d5\u05d8\u05e4\u05d5\u05d2\u05d5\" associated with language code he, using the same description text."}}],"*":"See https:\/\/www.wikidata.org\/w\/api.php for API usage. Subscribe to the mediawiki-api-announce mailing list at <https:\/\/lists.wikimedia.org\/mailman\/listinfo\/mediawiki-api-announce> for notice of API deprecations and breaking changes."},"servedby":"mw1228"} in /mnt/nfs/labstore-secondary-tools-project/ytcleaner/vendor/addwiki/mediawiki-api-base/src/MediawikiApi.php:374

I'm getting similar errors for Q80845 (fr label), Q38568 (pl label), Q80955 (he label), Q17479 (en label). I swapped the label and the alias for these items and then swapped them back using the web interface and don't run into issues then.

Event Timeline

Mbch331 created this task.Jan 19 2020, 5:41 PM
Restricted Application added subscribers: Liuxinyu970226, Aklapper. · View Herald TranscriptJan 19 2020, 5:41 PM

Can you give us more detail on what was the original API call?

Addshore triaged this task as High priority.Jan 20 2020, 1:34 PM
Addshore added a subscriber: Addshore.

High prio as this needs investigating sooner rather than later.

Looking at the history, I think I know what's going on here. Frontend and API usually send baserevid and that determines what's going to change on the item, if it thinks that it's going to change the label, it's going to try to make sure it doesn't violate the uniqueness constraint, I suggested back then to make sure you remove self-conflict errors for this exact reason, we never know if it would make its way to conflict check or not. First, let me reproduce it and then apply a fix.

I'm using the Addwiki library to save a new revision. The data that is sent to the API can be found in P10226 (was a lot of information, so a paste would be better than dumping it in here. (As serialized by the Addwiki library)

Mbch331 updated the task description. (Show Details)Jan 20 2020, 5:28 PM

Okay I found out what's wrong, it's the "clear" option. It messes with perception of ChangeOpResult, because it think it added everything again. This is causing all sorts of problem like edit summaries like this: https://www.wikidata.org/w/index.php?title=Q81715970&diff=prev&oldid=1096133130 The API request with "clear" true errors out but works just fine if you remove the clear option.

Okay I found out what's wrong, it's the "clear" option. It messes with perception of ChangeOpResult, because it think it added everything again. This is causing all sorts of problem like edit summaries like this: https://www.wikidata.org/w/index.php?title=Q81715970&diff=prev&oldid=1096133130 The API request with "clear" true errors out but works just fine if you remove the clear option.

Then I need to dig in the Addwiki package to find out how to disable the clear. Because it gets added there.

Mbch331 added a comment.EditedJan 21 2020, 7:03 PM

Found the culprit in vendor/addwiki/wikibase-api/src/Api/Service/RevisionSaver.php :

// Always clear so that removing elements is possible
                        $params['clear'] = 'true';

And I can't override it in my code, so the solution has to come from the addwiki/wikibase-api package.

Ladsgroup added a comment.EditedJan 21 2020, 9:54 PM

I think it needs slightly more work than that. The current problem can be solved in several layers, we should fix it on our side as well but I really appreciate if addWiki don't send the whole entity, just diffs what's added and removed.

For the addwiki part talk to @Addshore he's the maintainer of the addwiki code

I submitted https://github.com/addwiki/wikibase-api/pull/57 to remove the clear parameter from addwiki/wikibase-api/src/Api/Service/RevisionSaver.php as it isn't needed to remove a statement.

Sending diffs is better, but requires more work in the code, which I'll leave to others.

Restricted Application added a project: User-Addshore. · View Herald TranscriptJan 28 2020, 1:11 PM

Actually I have an idea that might not be too complicated to write, it's basically diffing and patching. Are you working on it already @Addshore ?

Stealing it. I have some idea I'm going to try. Let's see how that works

Restricted Application added a project: User-Ladsgroup. · View Herald TranscriptJan 28 2020, 2:50 PM

Change 568066 had a related patch set uploaded (by Ladsgroup; owner: Ladsgroup):
[mediawiki/extensions/Wikibase@master] Validate ChangeOp against the current entity instead of an empty one

https://gerrit.wikimedia.org/r/568066

Change 568490 had a related patch set uploaded (by Ladsgroup; owner: Ladsgroup):
[mediawiki/extensions/WikibaseLexeme@master] Throw right exception when trying to apply change on non-existent subentity

https://gerrit.wikimedia.org/r/568490

Change 568490 merged by jenkins-bot:
[mediawiki/extensions/WikibaseLexeme@master] Throw right exception when trying to apply change on non-existent subentity

https://gerrit.wikimedia.org/r/568490

Change 568066 merged by jenkins-bot:
[mediawiki/extensions/Wikibase@master] Validate ChangeOp against the current entity instead of an empty one

https://gerrit.wikimedia.org/r/568066