Attach Tracker State to OutputChannel (#619)

* attach tracker state to channel

* add changelog

* update type hint for OutputChannel

* Update changelog/619.improvement.md

Co-authored-by: aleksandarmijat <162149565+aleksandarmijat@users.noreply.github.com>

---------

Co-authored-by: aleksandarmijat <162149565+aleksandarmijat@users.noreply.github.com>

changelog/619.improvement.md

@@ -0,0 +1 @@
+Adds `tracker_state` attribute to `OutputChannel`. It simplifies the access of tracker state for custom channel connector with `CollectingOutputChannel.tracker_state`.

rasa/core/channels/channel.py

@@ -20,6 +20,10 @@
 from rasa.shared.constants import DOCS_BASE_URL, DEFAULT_SENDER_ID
 from rasa.core.constants import BEARER_TOKEN_PREFIX
 from rasa.shared.exceptions import RasaException
+from rasa.shared.core.trackers import (
+    DialogueStateTracker,
+    EventVerbosity,
+)
 
 try:
     from urlparse import urljoin
@@ -227,6 +231,10 @@ def name(cls) -> Text:
         """Every output channel needs a name to identify it."""
         return cls.__name__
 
+    def attach_tracker_state(self, tracker: DialogueStateTracker) -> None:
+        """Attaches the current tracker state to the output channel."""
+        self.tracker_state = tracker.current_state(EventVerbosity.AFTER_RESTART)
+
     async def send_response(self, recipient_id: Text, message: Dict[Text, Any]) -> None:
         """Send a message to the client."""
         if message.get("quick_replies"):

rasa/core/processor.py

@@ -1006,9 +1006,11 @@ async def execute_side_effects(
         self,
         events: List[Event],
         tracker: DialogueStateTracker,
-        output_channel: OutputChannel,
+        output_channel: Optional[OutputChannel],
     ) -> None:
-        """Send bot messages, schedule and cancel reminders."""
+        """Attach tracker, send bot messages, schedule and cancel reminders."""
+        if output_channel:
+            output_channel.attach_tracker_state(tracker)
         await self._send_bot_messages(events, tracker, output_channel)
         await self._schedule_reminders(events, tracker, output_channel)
         await self._cancel_reminders(events, tracker)