bcquality/microsoft/knowledge/events/add-new-event-parameters-at-the-end.md

bc-version	domain	keywords	technologies	countries	application-area
all	events	event-parameters signature backward-compatibility public-event local-event internal-event appsourcecop as0024 as0025	al	w1	all

Event parameter additions depend on publisher access, not position

Description

Event subscribers bind publisher parameters by name and can omit parameters they do not use. A local or internal Business or Integration event can therefore gain a parameter at any position without breaking subscriber-only consumers; appending is not a compatibility requirement. A public event is also a public procedure that dependent extensions can raise, so adding a required parameter anywhere breaks callers under AppSourceCop AS0024.

Best Practice

Add a parameter directly only when the shipped event publisher is local or internal. Place it where the signature is clearest; existing subscribers continue binding the parameters they name. For a public event, keep the original publisher unchanged and introduce a new event with the expanded contract.

See sample: add-new-event-parameters-at-the-end.good.al.

Anti Pattern

Appending a parameter to a public event and assuming its position makes the change compatible. Existing external callers still lack the new required argument. Conversely, do not flag a parameter inserted among existing parameters on a local or internal Business or Integration event merely because it was not appended.

See sample: add-new-event-parameters-at-the-end.bad.al.