Just added this to a bunch of properties using a complex constraint: https://www.wikidata.org/w/index.php?sort=relevance&search=%22key+language%22&title=Special:Search&profile=advanced&fulltext=1&advancedSearch-current=%7B%7D&ns121=1 . Normal constraint would be nicer.

This new constraint would get plenty of usage, see https://www.wikidata.org/wiki/Help:Property_constraints_portal/Label_language

My devil's advocate questions:

• I assume that the main purpose of all constraint types is to inform editors of mistakes or suggestions that would otherwise not be obvious. I also assume that all Items should have both labels and descriptions in virtually all supported languages. Why should users be told that the lack of a label in one language is a mistake and shouldn't be told the same about a label in another language that is more relevant (e.g. more demanded by Wikipedia) or more familiar to the user?
• Would it be expected that users who didn't previously fill in labels would switch to filling them in as a result of these violations? Or would these violations be ignored and contribute to all constraint types being ignored more?
• Might labels that were not suggested by these constraints be more neglected?

In T195178#7122976, @abian wrote:

• I assume that the main purpose of all constraint types is to inform editors of mistakes or suggestions that would otherwise not be obvious. I also assume that all Items should have both labels and descriptions in virtually all supported languages.

I think both assumptions are just yours.

1. Why did you make them?
2. Is there anything in Help:Property_constraints_portal/Label_language that lead you to assume this?
3. Isn't the contributor already shown that labels in languages relevant them are missing?

In T195178#7122976, @abian wrote:

My devil's advocate questions:
<knip>

Not sure about what your intentions are with these questions. I'll just assume good faith thus ignorance. We have a lot of art related properties we use for sourcing and linking, for example https://www.wikidata.org/wiki/Property:P5499 .
The source provides a valid label in a language (in this case Dutch) so it should always be set. If it's not set it usually means the item needs attention, exactly what we have constraint violations for. In the example we have 6 items out of 8700 that need attention: https://w.wiki/3Qbp . Just like with every other constraint, it should be used with care, but that's a meta discussion that should happen here (see https://www.mediawiki.org/wiki/Bug_management/Phabricator_etiquette ).

In T195178#7123731, @Multichill wrote:

Not sure about what your intentions are with these questions. I'll just assume good faith

Hey. Of course there's no bad intention; I don't know why I should have bad intentions towards you, you've never harmed me or my family (because you haven't... have you? 😅).

In T195178#7122976, @abian wrote:

My devil's advocate questions:

• I assume that the main purpose of all constraint types is to inform editors of mistakes or suggestions that would otherwise not be obvious. I also assume that all Items should have both labels and descriptions in virtually all supported languages. Why should users be told that the lack of a label in one language is a mistake and shouldn't be told the same about a label in another language that is more relevant (e.g. more demanded by Wikipedia) or more familiar to the user?
• Would it be expected that users who didn't previously fill in labels would switch to filling them in as a result of these violations? Or would these violations be ignored and contribute to all constraint types being ignored more?
• Might labels that were not suggested by these constraints be more neglected?

I usually leave these kinds of questions on Phabricator to try to assess in advance possible problems I can think of that might (or might not) arise after the possible implementation. The questions aren't ironic, I really don't know the answers but I do think they're relevant. There are a couple of dozen constraint types considered or proposed for implementation, so the first question would serve to justify why this constraint type would be particularly helpful; the second question is related to the problem of habituation to warnings, which is already occurring on Wikidata and we know both indirect figures and individual users who routinely ignore these warnings, but this problem will evolve and new warnings could make it worse or better; and the third would be another question to think about whether the overall balance of obeying the warnings would be positive for Wikidata (re)users or not. Of course I don't have these answers nor a special interest that this constraint type isn't implemented... until you harm me or my family, in which case I won't hesitate to add a dislike token to this very task.

Concerns about someone's family and the constraint system in general are hardly relevant to this.

😂

We need some input: How would the constraint statement look in your opinion? Should we use "Wikimedia Language Code (P424)" as the qualifier? A new Property?

I would like to have "If several languages are provided in the constraint then the constraint is satisfied if at least one of the languages has a label added" changed to "If several languages are provided in the constraint then the constraint is satisfied if all of the listed languages have a label added" (so not OR, but AND)

In T195178#7141368, @Lydia_Pintscher wrote:

We need some input: How would the constraint statement look in your opinion? Should we use "Wikimedia Language Code (P424)" as the qualifier? A new Property?

On https://www.wikidata.org/wiki/Property:P650 we use " language of work or name (P407) " set to a language " Dutch (Q7411)". The language has the " Wikimedia language code (P424) " set to "nl". I would use the same property P407 for this constraint.

I would like to have "If several languages are provided in the constraint then the constraint is satisfied if at least one of the languages has a label added" changed to "If several languages are provided in the constraint then the constraint is satisfied if all of the listed languages have a label added" (so not OR, but AND)

You can always achieve that effect by having several independent constraints. On the other hand, if we go for AND, there’s no way to emulate OR. So going for OR is more flexible.

In T195178#7141368, @Lydia_Pintscher wrote:

We need some input: How would the constraint statement look in your opinion? Should we use "Wikimedia Language Code (P424)" as the qualifier? A new Property?

On https://www.wikidata.org/wiki/Property:P650 we use " language of work or name (P407) " set to a language " Dutch (Q7411)". The language has the " Wikimedia language code (P424) " set to "nl". I would use the same property P407 for this constraint.

Hmmm that would make it quite a bit more complex and introduce the corner cases where the Item for the language doesn't have a statement for Wikimedia language code or when there are several. "language of work or name" also doesn't seem like a great Property for this to me tbh.

More thoughts?

This will have one slightly unusual consequence. Currently, we re-check constraints after a statement is saved, to update the indicators that are shown, in case a statement edit resolved another constraint violation (e.g. the statement of “item requires statement” was added). This new constraint type will, I believe, be the first one that may be resolved by non-statement edits to the same entity. Should we add some code to also re-check constraints after a label edit?

Change 713671 had a related patch set uploaded (by Ladsgroup; author: Amir Sarabadani):

[mediawiki/extensions/WikibaseQualityConstraints@master] [WIP] Introduce LabelInLanguageChecker

https://gerrit.wikimedia.org/r/713671

In T195178#7275103, @Lucas_Werkmeister_WMDE wrote:

This new constraint type will, I believe, be the first one that may be resolved by non-statement edits to the same entity.

Not true, T200689: Add “language required by this lexeme” constraint type already exists.

Change 713671 merged by jenkins-bot:

[mediawiki/extensions/WikibaseQualityConstraints@master] Introduce LabelInLanguageChecker

https://gerrit.wikimedia.org/r/713671

Test onwiki: constraint addition, sample statement

In T195178#7335945, @Esc3300 wrote:

Test onwiki: constraint addition, sample statement

It's not deployed yet. It'll be deployed next week (no train this week)

In T195178#7335946, @Ladsgroup wrote:

In T195178#7335945, @Esc3300 wrote:

Test onwiki: constraint addition, sample statement

It's not deployed yet. It'll be deployed next week (no train this week)

Did we go for the AND or OR implementation?

OR, as stated in the notes:

• If several languages are provided in the constraint then the constraint is satisfied if at least one of the languages has a label added.

The documentation still seems to be missing here.

Added (also for T200689).

Thanks for implementing this. I finally got around to update https://www.wikidata.org/wiki/Module:Constraints so that pages like https://www.wikidata.org/wiki/Property_talk:P650 are not throwing a horrible alert anymore. I also filed T303670 to make the same constraint for descriptions.