Adjust requested by @degiz

RasaHQ#5767 (review)

Author: lluchini

rasa/core/actions/action.py

@@ -166,6 +166,7 @@ async def run(
         nlg: "NaturalLanguageGenerator",
         tracker: "DialogueStateTracker",
         domain: "Domain",
+        metadata: Optional[Dict] = None,
     ) -> List[Event]:
         """
         Execute the side effects of this action.
@@ -178,7 +179,8 @@ async def run(
                 ``tracker.get_slot(slot_name)`` and the most recent user
                 message is ``tracker.latest_message.text``.
             domain (Domain): the bot's domain
-
+            metadata: dictionary that can be sent to action server with custom
+            data.
         Returns:
             List[Event]: A list of :class:`rasa.core.events.Event` instances
         """
@@ -205,6 +207,7 @@ async def run(
         nlg: "NaturalLanguageGenerator",
         tracker: "DialogueStateTracker",
         domain: "Domain",
+        metadata: Optional[Dict] = None,
     ):
         """Query the appropriate response and create a bot utterance with that."""
 
@@ -255,6 +258,7 @@ async def run(
         nlg: "NaturalLanguageGenerator",
         tracker: "DialogueStateTracker",
         domain: "Domain",
+        metadata: Optional[Dict] = None,
     ) -> List[Event]:
         """Simple run implementation uttering a (hopefully defined) template."""
 
@@ -291,6 +295,7 @@ async def run(
         nlg: "NaturalLanguageGenerator",
         tracker: "DialogueStateTracker",
         domain: "Domain",
+        metadata: Optional[Dict] = None,
     ) -> List[Event]:
         # only utter the template if it is available
         evts = await super().run(output_channel, nlg, tracker, domain)
@@ -313,6 +318,7 @@ async def run(
         nlg: "NaturalLanguageGenerator",
         tracker: "DialogueStateTracker",
         domain: "Domain",
+        metadata: Optional[Dict] = None,
     ) -> List[Event]:
         return []
 
@@ -334,6 +340,7 @@ async def run(
         nlg: "NaturalLanguageGenerator",
         tracker: "DialogueStateTracker",
         domain: "Domain",
+        metadata: Optional[Dict] = None,
     ) -> List[Event]:
         from rasa.core.events import Restarted
 
@@ -373,10 +380,11 @@ async def run(
         nlg: "NaturalLanguageGenerator",
         tracker: "DialogueStateTracker",
         domain: "Domain",
+        metadata: Optional[Dict] = None,
     ) -> List[Event]:
         from rasa.core.events import SessionStarted
 
-        _events = [SessionStarted()]
+        _events = [SessionStarted(metadata=metadata)]
 
         if domain.session_config.carry_over_slots:
             _events.extend(self._slot_set_events_from_tracker(tracker))
@@ -402,6 +410,7 @@ async def run(
         nlg: "NaturalLanguageGenerator",
         tracker: "DialogueStateTracker",
         domain: "Domain",
+        metadata: Optional[Dict] = None,
     ) -> List[Event]:
         from rasa.core.events import UserUtteranceReverted
 
@@ -423,6 +432,7 @@ async def run(
         nlg: "NaturalLanguageGenerator",
         tracker: "DialogueStateTracker",
         domain: "Domain",
+        metadata: Optional[Dict] = None,
     ) -> List[Event]:
         from rasa.core.events import Form, SlotSet
 
@@ -526,6 +536,7 @@ async def run(
         nlg: "NaturalLanguageGenerator",
         tracker: "DialogueStateTracker",
         domain: "Domain",
+        metadata: Optional[Dict] = None,
     ) -> List[Event]:
         json_body = self._action_call_format(tracker, domain)
 
@@ -630,6 +641,7 @@ async def run(
         nlg: "NaturalLanguageGenerator",
         tracker: "DialogueStateTracker",
         domain: "Domain",
+        metadata: Optional[Dict] = None,
     ) -> List[Event]:
         from rasa.core.policies.two_stage_fallback import has_user_rephrased
 
@@ -709,6 +721,7 @@ async def run(
         nlg: "NaturalLanguageGenerator",
         tracker: "DialogueStateTracker",
         domain: "Domain",
+        metadata: Optional[Dict] = None,
     ) -> List[Event]:
         intent_to_affirm = tracker.latest_message.intent.get("name")
         affirmation_message = f"Did you mean '{intent_to_affirm}'?"

rasa/core/processor.py

@@ -172,14 +172,12 @@ async def _update_tracker_session(
                 f"Starting a new session for conversation ID '{tracker.sender_id}'."
             )
 
-            if not (SessionStarted in tracker.events) and metadata:
-                tracker.events.append(SessionStarted(metadata=metadata))
-
             await self._run_action(
                 action=self._get_action(ACTION_SESSION_START_NAME),
                 tracker=tracker,
                 output_channel=output_channel,
                 nlg=self.nlg,
+                metadata=metadata,
             )
 
     async def get_tracker_with_session_start(
@@ -636,12 +634,24 @@ async def _cancel_reminders(
                         scheduler.remove_job(scheduled_job.id)
 
     async def _run_action(
-        self, action, tracker, output_channel, nlg, policy=None, confidence=None
+        self,
+        action,
+        tracker,
+        output_channel,
+        nlg,
+        policy=None,
+        confidence=None,
+        metadata: Optional[Dict] = None,
     ) -> bool:
         # events and return values are used to update
         # the tracker state after an action has been taken
         try:
-            events = await action.run(output_channel, nlg, tracker, self.domain)
+            if action.name() == ACTION_SESSION_START_NAME:
+                events = await action.run(
+                    output_channel, nlg, tracker, self.domain, metadata=metadata
+                )
+            else:
+                events = await action.run(output_channel, nlg, tracker, self.domain)
         except ActionExecutionRejection:
             events = [ActionExecutionRejected(action.name(), policy, confidence)]
             tracker.update(events[0])