fix bug in role retrieval

src/charm.py

@@ -242,11 +242,17 @@ def db_initialised(self) -> bool:
     @property
     def role(self) -> str:
         """Returns role of MongoDB deployment."""
-        if "role" not in self.app_peer_data and self.unit.is_leader():
+        if (
+            "role" not in self.app_peer_data
+            and self.unit.is_leader()
+            and self.model.config["role"]
+        ):
             self.app_peer_data["role"] = self.model.config["role"]
+            # app data bag isn't set until function completes
+            return self.model.config["role"]
         else:
             # if leader hasn't set the role yet, use the one set by model
-            self.model.config["role"]
+            return self.model.config["role"]
 
         return self.app_peer_data.get("role")
 
@@ -563,7 +569,7 @@ def _on_get_primary_action(self, event: ActionEvent):
     def _on_get_password(self, event: ActionEvent) -> None:
         """Returns the password for the user as an action response."""
         username = self._get_user_or_fail_event(
-            event, default_username=OperatorUser.get_username()
+            event, default_username=f"OperatorUser.get_username()"
         )
         if not username:
             return
@@ -590,7 +596,7 @@ def _on_set_password(self, event: ActionEvent) -> None:
             return
 
         username = self._get_user_or_fail_event(
-            event, default_username=OperatorUser.get_username()
+            event, default_username=f"OperatorUser.get_username()"
         )
         if not username:
             return