Bundle relations of relations into the /relations result.

changelog.d/11284.feature

@@ -0,0 +1 @@
+Include bundled relations in response to the `/relations` API, per [MSC3440](https://github.com/matrix-org/matrix-doc/pull/3440).

synapse/events/utils.py

@@ -398,7 +398,7 @@ async def serialize_event(
         """Serializes a single event.
 
         Args:
-            event
+            event: The event being serialized.
             time_now: The current time in milliseconds
             bundle_aggregations: Whether to bundle in related events
             **kwargs: Arguments to pass to `serialize_event`
@@ -410,7 +410,6 @@ async def serialize_event(
         if not isinstance(event, EventBase):
             return event
 
-        event_id = event.event_id
         serialized_event = serialize_event(event, time_now, **kwargs)
 
         # If MSC1849 is enabled then we need to look if there are any relations
@@ -419,68 +418,91 @@ async def serialize_event(
         if not event.internal_metadata.is_redacted() and (
             self._msc1849_enabled and bundle_aggregations
         ):
-            annotations = await self.store.get_aggregation_groups_for_event(event_id)
-            references = await self.store.get_relations_for_event(
-                event_id, RelationTypes.REFERENCE, direction="f"
-            )
-
-            if annotations.chunk:
-                r = serialized_event["unsigned"].setdefault("m.relations", {})
-                r[RelationTypes.ANNOTATION] = annotations.to_dict()
-
-            if references.chunk:
-                r = serialized_event["unsigned"].setdefault("m.relations", {})
-                r[RelationTypes.REFERENCE] = references.to_dict()
-
-            edit = None
-            if event.type == EventTypes.Message:
-                edit = await self.store.get_applicable_edit(event_id)
-
-            if edit:
-                # If there is an edit replace the content, preserving existing
-                # relations.
-
-                # Ensure we take copies of the edit content, otherwise we risk modifying
-                # the original event.
-                edit_content = edit.content.copy()
-
-                # Unfreeze the event content if necessary, so that we may modify it below
-                edit_content = unfreeze(edit_content)
-                serialized_event["content"] = edit_content.get("m.new_content", {})
-
-                # Check for existing relations
-                relations = event.content.get("m.relates_to")
-                if relations:
-                    # Keep the relations, ensuring we use a dict copy of the original
-                    serialized_event["content"]["m.relates_to"] = relations.copy()
-                else:
-                    serialized_event["content"].pop("m.relates_to", None)
-
-                r = serialized_event["unsigned"].setdefault("m.relations", {})
-                r[RelationTypes.REPLACE] = {
-                    "event_id": edit.event_id,
-                    "origin_server_ts": edit.origin_server_ts,
-                    "sender": edit.sender,
-                }
-
-            # If this event is the start of a thread, include a summary of the replies.
-            if self._msc3440_enabled:
-                (
-                    thread_count,
-                    latest_thread_event,
-                ) = await self.store.get_thread_summary(event_id)
-                if latest_thread_event:
-                    r = serialized_event["unsigned"].setdefault("m.relations", {})
-                    r[RelationTypes.THREAD] = {
-                        # Don't bundle aggregations as this could recurse forever.
-                        "latest_event": await self.serialize_event(
-                            latest_thread_event, time_now, bundle_aggregations=False
-                        ),
-                        "count": thread_count,
-                    }
+            await self._injected_bundled_relations(event, time_now, serialized_event)
 
         return serialized_event
 
+    async def _injected_bundled_relations(
+        self, event: EventBase, time_now: int, serialized_event: JsonDict
+    ) -> None:
+        """Potentially injects bundled relations into the unsigend portion of the serialized event.
+
+        Args:
+            event: The event being serialized.
+            time_now: The current time in milliseconds
+            serialized_event: The serialized event which may be modified.
+
+        """
+        # Do not bundle aggregations for an event which represents an edit or annotation.
+        relates_to = event.content.get("m.relates_to")
+        if isinstance(relates_to, (dict, frozendict)):
+            relation_type = relates_to.get("rel_type")
+            if relation_type in (RelationTypes.ANNOTATION, RelationTypes.REPLACE):
+                return
+
+        event_id = event.event_id
+
+        annotations = await self.store.get_aggregation_groups_for_event(event_id)
+        references = await self.store.get_relations_for_event(
+            event_id, RelationTypes.REFERENCE, direction="f"
+        )
+
+        relations = {}
+
+        if annotations.chunk:
+            relations[RelationTypes.ANNOTATION] = annotations.to_dict()
+
+        if references.chunk:
+            relations[RelationTypes.REFERENCE] = references.to_dict()
+
+        edit = None
+        if event.type == EventTypes.Message:
+            edit = await self.store.get_applicable_edit(event_id)
+
+        if edit:
+            # If there is an edit replace the content, preserving existing
+            # relations.
+
+            # Ensure we take copies of the edit content, otherwise we risk modifying
+            # the original event.
+            edit_content = edit.content.copy()
+
+            # Unfreeze the event content if necessary, so that we may modify it below
+            edit_content = unfreeze(edit_content)
+            serialized_event["content"] = edit_content.get("m.new_content", {})
+
+            # Check for existing relations
+            if relates_to:
+                # Keep the relations, ensuring we use a dict copy of the original
+                serialized_event["content"]["m.relates_to"] = relates_to.copy()
+            else:
+                serialized_event["content"].pop("m.relates_to", None)
+
+            relations[RelationTypes.REPLACE] = {
+                "event_id": edit.event_id,
+                "origin_server_ts": edit.origin_server_ts,
+                "sender": edit.sender,
+            }
+
+        # If this event is the start of a thread, include a summary of the replies.
+        if self._msc3440_enabled:
+            (
+                thread_count,
+                latest_thread_event,
+            ) = await self.store.get_thread_summary(event_id)
+            if latest_thread_event:
+                relations[RelationTypes.THREAD] = {
+                    # Don't bundle aggregations as this could recurse forever.
+                    "latest_event": await self.serialize_event(
+                        latest_thread_event, time_now, bundle_aggregations=False
+                    ),
+                    "count": thread_count,
+                }
+
+        # If any bundled relations were found, include them.
+        if relations:
+            serialized_event["unsigned"].setdefault("m.relations", {}).update(relations)
+
     async def serialize_events(
         self, events: Iterable[Union[JsonDict, EventBase]], time_now: int, **kwargs: Any
     ) -> List[JsonDict]:

synapse/rest/client/relations.py

@@ -230,12 +230,9 @@ async def on_GET(
         original_event = await self._event_serializer.serialize_event(
             event, now, bundle_aggregations=False
         )
-        # Similarly, we don't allow relations to be applied to relations, so we
-        # return the original relations without any aggregations on top of them
-        # here.
-        serialized_events = await self._event_serializer.serialize_events(
-            events, now, bundle_aggregations=False
-        )
+        # For any relations applying to the original event they need their
+        # aggregations applied to them.
+        serialized_events = await self._event_serializer.serialize_events(events, now)
 
         return_value = pagination_chunk.to_dict()
         return_value["chunk"] = serialized_events

tests/rest/client/test_relations.py

@@ -461,6 +461,74 @@ def test_aggregation_get_event(self):
             },
         )
 
+    def test_aggregation_get_event_for_annotation(self):
+        """Test that annotations do not get bundled relations included
+        when directly requested.
+        """
+        channel = self._send_relation(RelationTypes.ANNOTATION, "m.reaction", "a")
+        self.assertEquals(200, channel.code, channel.json_body)
+        annotation_id = channel.json_body["event_id"]
+
+        # Annotate the annotation.
+        channel = self._send_relation(
+            RelationTypes.ANNOTATION, "m.reaction", "a", parent_id=annotation_id
+        )
+        self.assertEquals(200, channel.code, channel.json_body)
+
+        channel = self.make_request(
+            "GET",
+            f"/rooms/{self.room}/event/{annotation_id}",
+            access_token=self.user_token,
+        )
+        self.assertEquals(200, channel.code, channel.json_body)
+        self.assertIsNone(channel.json_body["unsigned"].get("m.relations"))
+
+    def test_aggregation_get_event_for_thread(self):
+        """Test that threads get bundled relations included when directly requested."""
+        channel = self._send_relation(RelationTypes.THREAD, "m.room.test")
+        self.assertEquals(200, channel.code, channel.json_body)
+        thread_id = channel.json_body["event_id"]
+
+        # Annotate the annotation.
+        channel = self._send_relation(
+            RelationTypes.ANNOTATION, "m.reaction", "a", parent_id=thread_id
+        )
+        self.assertEquals(200, channel.code, channel.json_body)
+
+        channel = self.make_request(
+            "GET",
+            f"/rooms/{self.room}/event/{thread_id}",
+            access_token=self.user_token,
+        )
+        self.assertEquals(200, channel.code, channel.json_body)
+        self.assertEquals(
+            channel.json_body["unsigned"].get("m.relations"),
+            {
+                RelationTypes.ANNOTATION: {
+                    "chunk": [{"count": 1, "key": "a", "type": "m.reaction"}]
+                },
+            },
+        )
+
+        # It should also be included when the entire thread is requested.
+        channel = self.make_request(
+            "GET",
+            f"/_matrix/client/unstable/rooms/{self.room}/relations/{self.parent_id}?limit=1",
+            access_token=self.user_token,
+        )
+        self.assertEquals(200, channel.code, channel.json_body)
+        self.assertEqual(len(channel.json_body["chunk"]), 1)
+
+        thread_message = channel.json_body["chunk"][0]
+        self.assertEquals(
+            thread_message["unsigned"].get("m.relations"),
+            {
+                RelationTypes.ANNOTATION: {
+                    "chunk": [{"count": 1, "key": "a", "type": "m.reaction"}]
+                },
+            },
+        )
+
     def test_edit(self):
         """Test that a simple edit works."""
 
@@ -607,6 +675,56 @@ def test_edit_reply(self):
             {"event_id": edit_event_id, "sender": self.user_id}, m_replace_dict
         )
 
+    def test_edit_edit(self):
+        """Test that an edit cannot be edited."""
+        new_body = {"msgtype": "m.text", "body": "Initial edit"}
+        channel = self._send_relation(
+            RelationTypes.REPLACE,
+            "m.room.message",
+            content={
+                "msgtype": "m.text",
+                "body": "Wibble",
+                "m.new_content": new_body,
+            },
+        )
+        self.assertEquals(200, channel.code, channel.json_body)
+        edit_event_id = channel.json_body["event_id"]
+
+        # Edit the edit event.
+        channel = self._send_relation(
+            RelationTypes.REPLACE,
+            "m.room.message",
+            content={
+                "msgtype": "m.text",
+                "body": "foo",
+                "m.new_content": {"msgtype": "m.text", "body": "Ignored edit"},
+            },
+            parent_id=edit_event_id,
+        )
+        self.assertEquals(200, channel.code, channel.json_body)
+
+        # Request the original event.
+        channel = self.make_request(
+            "GET",
+            "/rooms/%s/event/%s" % (self.room, self.parent_id),
+            access_token=self.user_token,
+        )
+        self.assertEquals(200, channel.code, channel.json_body)
+        # The edit to the edit should be ignored.
+        self.assertEquals(channel.json_body["content"], new_body)
+
+        # The relations information should not include the edit to the edit.
+        relations_dict = channel.json_body["unsigned"].get("m.relations")
+        self.assertIn(RelationTypes.REPLACE, relations_dict)
+
+        m_replace_dict = relations_dict[RelationTypes.REPLACE]
+        for key in ["event_id", "sender", "origin_server_ts"]:
+            self.assertIn(key, m_replace_dict)
+
+        self.assert_dict(
+            {"event_id": edit_event_id, "sender": self.user_id}, m_replace_dict
+        )
+
     def test_relations_redaction_redacts_edits(self):
         """Test that edits of an event are redacted when the original event
         is redacted.