real-time sync: Server sends recipent data with delete_message event.

Fixes #8853.
In certain cases, the browser is not able to look up the message.
Include the recipient data for the message in the delete_message event,
so look up of those attributes by the browser isn't required.

frontend_tests/node_tests/dispatch.js

@@ -479,6 +479,9 @@ var event_fixtures = {
     delete_message: {
         type: 'delete_message',
         message_id: 1337,
+        message_type: "stream",
+        stream_id: 99,
+        topic: 'topic1',
     },
 
     custom_profile_fields: {
@@ -942,13 +945,6 @@ set_global('message_store', {});
 with_overrides(function (override) {
     // delete_message
     var event = event_fixtures.delete_message;
-    message_store.get = function (msg_id) {
-        return { id: msg_id,
-             reactions: [],
-             stream_id: 99,
-             subject: 'topic1',
-             type: 'stream'};
-    };
 
     override('stream_list.update_streams_sidebar', noop);
     global.with_stub(function (stub) {

static/js/server_events_dispatch.js

@@ -394,15 +394,14 @@ exports.dispatch_normal_event = function dispatch_normal_event(event) {
 
     case 'delete_message':
         var msg_id = event.message_id;
-        var message = message_store.get(msg_id);
         // message is passed to unread.get_unread_messages,
         // which returns all the unread messages out of a given list.
         // So double marking something as read would not occur
         unread_ops.process_read_messages_event([msg_id]);
-        if (message.type === 'stream') {
+        if (event.message_type === 'stream') {
             topic_data.remove_message({
-                stream_id: message.stream_id,
-                topic_name: message.subject,
+                stream_id: event.stream_id,
+                topic_name: event.topic,
             });
             stream_list.update_streams_sidebar();
         }

zerver/lib/actions.py

@@ -3737,10 +3737,21 @@ def do_update_message(user_profile: UserProfile, message: Message, topic_name: O
 
 
 def do_delete_message(user_profile: UserProfile, message: Message) -> None:
+    message_type = "stream"
+    if not message.is_stream_message():
+        message_type = "private"
+
     event = {
         'type': 'delete_message',
         'sender': user_profile.email,
-        'message_id': message.id}  # type: Dict[str, Any]
+        'message_id': message.id,
+        'message_type': message_type, }  # type: Dict[str, Any]
+    if message_type == "stream":
+        event['stream_id'] = message.recipient.type_id
+        event['topic'] = message.subject
+    else:
+        event['recipient_user_ids'] = message.recipient.type_id
+
     ums = [{'id': um.user_profile_id} for um in
            UserMessage.objects.filter(message=message.id)]
     move_message_to_archive(message.id)

zerver/tests/test_events.py

@@ -2023,11 +2023,14 @@ class EventsRegisterTest(ZulipTestCase):
         error = add_schema_checker('events[1]', events[1])
         self.assert_on_error(error)
 
-    def test_do_delete_message(self) -> None:
+    def test_do_delete_message_stream(self) -> None:
         schema_checker = self.check_events_dict([
             ('type', equals('delete_message')),
             ('message_id', check_int),
             ('sender', check_string),
+            ('message_type', equals("stream")),
+            ('stream_id', check_int),
+            ('topic', check_string),
         ])
         msg_id = self.send_stream_message("hamlet@zulip.com", "Verona")
         message = Message.objects.get(id=msg_id)
@@ -2038,6 +2041,27 @@ class EventsRegisterTest(ZulipTestCase):
         error = schema_checker('events[0]', events[0])
         self.assert_on_error(error)
 
+    def test_do_delete_message_personal(self) -> None:
+        schema_checker = self.check_events_dict([
+            ('type', equals('delete_message')),
+            ('message_id', check_int),
+            ('sender', check_string),
+            ('message_type', equals("private")),
+            ('recipient_user_ids', check_int),
+        ])
+        msg_id = self.send_personal_message(
+            self.example_email("cordelia"),
+            self.user_profile.email,
+            "hello",
+        )
+        message = Message.objects.get(id=msg_id)
+        events = self.do_test(
+            lambda: do_delete_message(self.user_profile, message),
+            state_change_expected=True,
+        )
+        error = schema_checker('events[0]', events[0])
+        self.assert_on_error(error)
+
     def test_do_delete_message_no_max_id(self) -> None:
         user_profile = self.example_user('aaron')
         # Delete all historical messages for this user