Why do we even need this… we apparently do some namespace-specific validation in it. Isn't ContentHandler supposed to call the validation functions automatically?

In T147566#2696984, @matmarex wrote:

Why do we even need this… we apparently do some namespace-specific validation in it. Isn't ContentHandler supposed to call the validation functions automatically?

Paging @daniel :)

It would indeed be nice if ContentHandler had a validate() methods that returns a Status object (or would return a meaningful message in some other way). But this is not the case, all we have right now is Content::isValue() which only returns a boolean. So using EditFilterMergedContent to do pre-save validation is probably the best option for now.

In T147566#2697543, @daniel wrote:

It would indeed be nice if ContentHandler had a validate() methods that returns a Status object (or would return a meaningful message in some other way). But this is not the case, all we have right now is Content::isValue() which only returns a boolean. So using EditFilterMergedContent to do pre-save validation is probably the best option for now.

That's T143761: Fix Content validation - something to replace Content::isValid() :)

Change 314625 had a related patch set uploaded (by Reedy):
Replace EditFilterMerged hook usage

https://gerrit.wikimedia.org/r/314625

Change 314625 merged by jenkins-bot:
Replace EditFilterMerged hook usage

https://gerrit.wikimedia.org/r/314625