internal_prep_stream_message: Support accepting a Stream object.

If the caller has access to a Stream object, it is wasteful to
query a database for a stream by ID or name. In addition, not
having to go through stream names eliminates various classes of
possible bugs involved with getting a Stream object back.

zerver/lib/actions.py

@@ -1688,9 +1688,10 @@ def prep_stream_welcome_message(stream: Stream) -> Optional[Dict[str, Any]]:
     message = internal_prep_stream_message(
         realm=realm,
         sender=sender,
-        stream_name=stream.name,
         topic=topic,
-        content=content)
+        content=content,
+        stream=stream
+    )
 
     return message
 
@@ -2224,8 +2225,10 @@ def check_message(sender: UserProfile, client: Client, addressee: Addressee,
 
         if stream_name is not None:
             stream = validate_stream_name_with_pm_notification(stream_name, realm, sender)
-        else:
+        elif stream_id is not None:
             stream = validate_stream_id_with_pm_notification(stream_id, realm, sender)
+        else:
+            stream = addressee.stream()
 
         recipient = get_stream_recipient(stream.id)
 
@@ -2320,13 +2323,20 @@ def _internal_prep_message(realm: Realm,
 
     return None
 
-def internal_prep_stream_message(realm: Realm, sender: UserProfile,
-                                 stream_name: str, topic: str,
-                                 content: str) -> Optional[Dict[str, Any]]:
+def internal_prep_stream_message(
+        realm: Realm, sender: UserProfile,
+        topic: str, content: str,
+        stream_name: Optional[str]=None,
+        stream: Optional[Stream]=None
+) -> Optional[Dict[str, Any]]:
     """
     See _internal_prep_message for details of how this works.
     """
-    addressee = Addressee.for_stream_name(stream_name, topic)
+    assert stream_name is not None or stream is not None
+    if stream is not None:
+        addressee = Addressee.for_stream(stream, topic)
+    else:
+        addressee = Addressee.for_stream_name(stream_name, topic)
 
     return _internal_prep_message(
         realm=realm,
@@ -2392,7 +2402,8 @@ def internal_send_private_message(realm: Realm,
 
 def internal_send_stream_message(realm: Realm, sender: UserProfile, stream_name: str,
                                  topic: str, content: str) -> None:
-    message = internal_prep_stream_message(realm, sender, stream_name, topic, content)
+    message = internal_prep_stream_message(realm, sender, topic,
+                                           content, stream_name=stream_name)
     if message is None:
         return
     do_send_messages([message])

zerver/lib/addressee.py

@@ -8,6 +8,7 @@ from zerver.models import (
     UserProfile,
     get_user_including_cross_realm,
     get_user_by_id_in_realm_including_cross_realm,
+    Stream,
 )
 
 def raw_pm_with_emails(email_str: str, my_email: str) -> List[str]:
@@ -63,12 +64,14 @@ class Addressee:
     # This should be treated as an immutable class.
     def __init__(self, msg_type: str,
                  user_profiles: Optional[Sequence[UserProfile]]=None,
+                 stream: Optional[Stream]=None,
                  stream_name: Optional[str]=None,
                  stream_id: Optional[int]=None,
                  topic: Optional[str]=None) -> None:
         assert(msg_type in ['stream', 'private'])
         self._msg_type = msg_type
         self._user_profiles = user_profiles
+        self._stream = stream
         self._stream_name = stream_name
         self._stream_id = stream_id
         self._topic = topic
@@ -83,6 +86,10 @@ class Addressee:
         assert(self.is_private())
         return self._user_profiles  # type: ignore # assertion protects us
 
+    def stream(self) -> Optional[Stream]:
+        assert(self.is_stream())
+        return self._stream
+
     def stream_name(self) -> Optional[str]:
         assert(self.is_stream())
         return self._stream_name
@@ -144,6 +151,15 @@ class Addressee:
         else:
             raise JsonableError(_("Invalid message type"))
 
+    @staticmethod
+    def for_stream(stream: Stream, topic: str) -> 'Addressee':
+        topic = validate_topic(topic)
+        return Addressee(
+            msg_type='stream',
+            stream=stream,
+            topic=topic,
+        )
+
     @staticmethod
     def for_stream_name(stream_name: str, topic: str) -> 'Addressee':
         topic = validate_topic(topic)

zerver/lib/onboarding.py

@@ -109,7 +109,9 @@ def send_initial_realm_messages(realm: Realm) -> None:
     ]  # type: List[Dict[str, str]]
     messages = [internal_prep_stream_message(
         realm, welcome_bot,
-        message['stream'], message['topic'], message['content']) for message in welcome_messages]
+        message['topic'], message['content'],
+        stream_name=message['stream']
+    ) for message in welcome_messages]
     message_ids = do_send_messages(messages)
 
     # We find the one of our just-sent messages with turtle.png in it,

zerver/tests/test_subs.py

@@ -2183,7 +2183,7 @@ class SubscriptionAPITest(ZulipTestCase):
                     streams_to_sub,
                     dict(principals=ujson.dumps([user1.email, user2.email])),
                 )
-        self.assert_length(queries, 45)
+        self.assert_length(queries, 43)
 
         self.assert_length(events, 7)
         for ev in [x for x in events if x['event']['type'] not in ('message', 'stream')]:
@@ -2944,7 +2944,7 @@ class SubscriptionAPITest(ZulipTestCase):
                 [new_streams[0]],
                 dict(principals=ujson.dumps([user1.email, user2.email])),
             )
-        self.assert_length(queries, 45)
+        self.assert_length(queries, 43)
 
         # Test creating private stream.
         with queries_captured() as queries:
@@ -2954,7 +2954,7 @@ class SubscriptionAPITest(ZulipTestCase):
                 dict(principals=ujson.dumps([user1.email, user2.email])),
                 invite_only=True,
             )
-        self.assert_length(queries, 40)
+        self.assert_length(queries, 38)
 
         # Test creating a public stream with announce when realm has a notification stream.
         notifications_stream = get_stream(self.streams[0], self.test_realm)
@@ -2969,7 +2969,7 @@ class SubscriptionAPITest(ZulipTestCase):
                     principals=ujson.dumps([user1.email, user2.email])
                 )
             )
-        self.assert_length(queries, 55)
+        self.assert_length(queries, 51)
 
 class GetPublicStreamsTest(ZulipTestCase):
 

zerver/views/streams.py

@@ -392,16 +392,17 @@ def add_subscriptions_backend(
             msg = ("_@**%s|%d** just created %s" % (user_profile.full_name, user_profile.id, stream_msg))
 
             sender = get_system_bot(settings.NOTIFICATION_BOT)
-            stream_name = notifications_stream.name
             topic = 'Streams'
 
             notifications.append(
                 internal_prep_stream_message(
                     realm=user_profile.realm,
                     sender=sender,
-                    stream_name=stream_name,
                     topic=topic,
-                    content=msg))
+                    content=msg,
+                    stream=notifications_stream
+                )
+            )
 
     if not user_profile.realm.is_zephyr_mirror_realm:
         for stream in created_streams:

zilencer/management/commands/add_mock_conversation.py

@@ -78,7 +78,9 @@ From image editing program:
         ]  # type: List[Dict[str, Any]]
 
         messages = [internal_prep_stream_message(
-            realm, message['sender'], stream.name, 'message formatting', message['content']
+            realm, message['sender'],
+            'message formatting', message['content'],
+            stream=stream
         ) for message in staged_messages]
 
         message_ids = do_send_messages(messages)