CheckUser extension should use EventBus.UserEntitySerializer service instead of constructor
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Description

In T392516: [EventBus] Stabilize EventSerializer and related classes EventBus' reusable entity serializers were exposed as MediaWiki Service objects.

The CheckUser extension's SuggestedInvestigationsInstrumentationClient constructs a new UserEntitySerializer directly.

In T423952: Create mediawiki.user_change event stream, we are evolving the UserEntitySerializer constructor. CI is complaining with:

ArgumentCountError: Too few arguments to function MediaWiki\Extension\EventBus\Serializers\MediaWiki\UserEntitySerializer::__construct(), 3 passed in /workspace/src/extensions/CheckUser/src/SuggestedInvestigations/Instrumentation/SuggestedInvestigationsInstrumentationClient.php on line 86 and exactly 4 expected

The CheckUser code was committed after we merged the new EventBus MW Services and adapted CirrusSearch to use them. I'm not sure how we missed CheckUser!

This is blocking T423952.

Done is

CheckUser uses EventBus.UserEntitySerializer MediaWiki Service instead of directly constructing instances.

Details

Related Changes in Gerrit:

	Subject	Repo	Branch	Lines +/-
	Use EventBus.UserEntitySerializer service	mediawiki/extensions/CheckUser	master	+12 -55

Customize query in gerrit

Related Objects
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Status	Assigned	Task
Open	None	T428273 Incremental MediaWiki History Phase II
Open	None	T291120 MediaWiki Event Carried State Transfer - Problem Statement
Open	Ottomata	T423935 Incremental MWH - MediaWiki event data source improvements
Open	Ottomata	T423952 Create mediawiki.user_change event stream
Resolved	Ottomata	T425801 CheckUser extension should use EventBus.UserEntitySerializer service instead of constructor
Open	None	T424887 mediawiki.page_change event - add access_method & platform details
Open	tchin	T425029 mediawiki.page_change.v1 - add revision.editor.first_edit_dt field
Open	Ottomata	T423583 mediawiki.page_change.v1 event - Add revision revert details
Open	None	T426998 mediawiki.page_change.v1 event - Add user first_registration_dt field
Open	None	T425996 Add log_id to mediawiki page_change and user_change events
Open	None	T427815 MediaWiki DomainEvents - Include LogEntry
Open	Ottomata	T428176 mediawiki.page_change.v1 events - add wikidata id for pages

Event Timeline

Ottomata created this task.May 8 2026, 5:09 PM

Restricted Application added a project: Product Safety and Integrity. · View Herald TranscriptMay 8 2026, 5:09 PM

@Dreamy_Jazz I was going to submit a patch to just inject EventBus.UserEntitySerializer into the SuggestedInvestigationsInstrumentationClient constructor via ServiceWiring.php, but, it looks like maybe EventBus extension is meant to be an optional dependency?

It is an optional dependency to avoid breaking tests in CI. In practice it's intended that a wiki with Suggested Investigations enabled would have EventBus installed.

So it should be a soft dependency but it's fine if that essentially disables the instrumentation when EventBus is not installed. So perhaps the same logic of using the no-op instrumentation client can happen when EventBus is not installed (as used for no EventLogging)

Ottomata claimed this task.May 8 2026, 7:58 PM

Ottomata triaged this task as High priority.

Change #1285427 had a related patch set uploaded (by Ottomata; author: Ottomata):

[mediawiki/extensions/CheckUser@master] Use EventBus.UserEntitySerializer service

https://gerrit.wikimedia.org/r/1285427

gerritbot added a project: Patch-For-Review.May 8 2026, 8:12 PM

Adding Product Safety and Integrity sprint to track code review

Dreamy_Jazz moved this task from Backlog to Needs review on the Product Safety and Integrity (Sprint lily-of-the-valley (May 4 - May 22)) board.May 8 2026, 8:28 PM

Change #1285427 merged by jenkins-bot:

[mediawiki/extensions/CheckUser@master] Use EventBus.UserEntitySerializer service

https://gerrit.wikimedia.org/r/1285427

Maintenance_bot removed a project: Patch-For-Review.May 8 2026, 10:31 PM

Dreamy_Jazz closed this task as Resolved.May 11 2026, 2:05 PM

Dreamy_Jazz moved this task from Needs review to Done on the Product Safety and Integrity (Sprint lily-of-the-valley (May 4 - May 22)) board.

Dreamy_Jazz updated the task description. (Show Details)

Aklapper mentioned this in T426026: ArgumentCountError: Too few arguments to function MediaWiki\Extension\EventBus\Serializers\MediaWiki\UserEntitySerializer::__construct(), 3 passed in /srv/mediawiki/php-1.47.0-wmf.2/extensions/WikimediaEvents/.May 12 2026, 8:46 AM

CheckUser extension should use EventBus.UserEntitySerializer service instead of constructorClosed, ResolvedPublicActions