I’m migrating away from the deprecated api.modifyClass("model:composer", ...). My current override of Composer#save conditionally changes the save behavior, but otherwise needs to call super.save(opts). I see the new addModelMethod / addModelCallback APIs, but I can’t find an example in core of us…

The best thing would be to add a new hook to Discourse core which allows you to achieve what you need in a supported way. How about something like this: DEV: Introduce `composer-minimum-post-length` valueTransformer (#42686) main …

I guess it would depend on what you’re overriding the save method to do… if you are looking to prevent a save based on some condition, you could use our composer-service-cannot-submit-post value transformer if you’re doing something once the post is created, there’s api.onAppEvent("post:created") …

Thanks! I’m already using composer-service-cannot-submit-post — it handles the service-level check. But the composer model’s save() also checks cantSubmitPost, which includes missingReplyCharacters > 0, so an empty body is still blocked there. onAppEvent("post:created") is too late because the post…

@david , would appreciate any input you might have on the best approach here.

Thanks David! I tested the composer-minimum-post-length transformer and it works — topics with empty bodies are created successfully. One thing I noticed: the editor still displays “Post can’t be empty” because the validation in composer-editor has a hard-coded replyLength < 1 check that doesn’t us…

[image] jahan_gagan: Could that check also respect the transformer, or be skipped when minimumPostLength is 0? Sounds good - added to the PR :+1:

Works perfectly now. Thank you so much for adding this, @david ! :raising_hands:

Recommended replacement for modifyClass("model:composer") when overriding save()

Development

david (David Taylor) August 19, 2026, 10:02pm 7

Sounds good - added to the PR

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Recommended replacement for modifyClass("model:composer") when overriding save()

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