PostStreamingResponseEvent never gets triggered

MR now triggers the event, when the StreamedChatMessageIterator object gets destructed.

Test PromptJsonDecoderTest seems to fail now, because \Drupal\ai\Event\PostStreamingResponseEvent::__construct doesn't receive a request_thread_id string in its constructor.
Not sure if this value is NULL in this test by design, or by accident.
If by design, then the PostStreamingResponseEvent $request_thread_id parameter should be allowed to be nullable?

Hi @svendecabooter,
The current destructor approach — it might be causing issues since it triggers for all iterator instances, including test objects.

Would it make sense to consider moving the triggerEvent() call to the ChatOutput constructor instead? That way:

- It would only fire for actual streaming responses
- It wouldn’t interfere with test objects or other unintended cases

Let me know what you think. Thanks!

@sarvjeetsingh:

I'm not sure if that would work - I'm still tipping my toes into how all of this works...

It would be something like this, in the ChatOutput constructor?:

    if ($normalized instanceof StreamedChatMessageIteratorInterface) {
      $normalized->triggerEvent();
    }

In my initial testing, that doesn't seem to work. I then get the same error as in the tests:
TypeError: Drupal\ai\Event\PostStreamingResponseEvent::__construct(): Argument #1 ($request_thread_id) must be of type string, null given

Not sure if that's something that also needs to be fixed, or if this means this approach is not workable...

Thanks for testing the ChatOutput approach!

You're right about the NULL `request_thread_id` issue. The PostStreamingResponseEvent `$request_thread_id` parameter might need to be nullable - I think that makes sense.

We could make that constructor accept nullable string if that would help resolve this issue. That might be the right approach.

I’ve made a few updates to fix the missing triggerEvent() call:

• Made $request_thread_id nullable in PostStreamingResponseEvent to avoid test failures.
• Added a $eventTriggered flag in StreamedChatMessageIterator to prevent duplicate events.
• Added null check in triggerEvent() and improved __destruct() for safety.
• Introduced finishStreaming() method so providers can trigger the event explicitly (recommended over relying on __destruct()).

Kindly review.