Add the topic and avatar to the room details admin API (#8305)

Author: tulir

changelog.d/8305.feature

@@ -0,0 +1 @@
+Add the room topic and avatar to the room details admin API.

docs/admin_api/rooms.md

@@ -275,6 +275,8 @@ The following fields are possible in the JSON response body:
 
 * `room_id` - The ID of the room.
 * `name` - The name of the room.
+* `topic` - The topic of the room.
+* `avatar` - The `mxc` URI to the avatar of the room.
 * `canonical_alias` - The canonical (main) alias address of the room.
 * `joined_members` - How many users are currently in the room.
 * `joined_local_members` - How many local users are currently in the room.
@@ -304,6 +306,8 @@ Response:
 {
   "room_id": "!mscvqgqpHYjBGDxNym:matrix.org",
   "name": "Music Theory",
+  "avatar": "mxc://matrix.org/AQDaVFlbkQoErdOgqWRgiGSV",
+  "topic": "Theory, Composition, Notation, Analysis",
   "canonical_alias": "#musictheory:matrix.org",
   "joined_members": 127
   "joined_local_members": 2,

synapse/storage/databases/main/room.py

@@ -104,7 +104,8 @@ def get_room_with_stats_txn(txn, room_id):
                   curr.local_users_in_room AS joined_local_members, rooms.room_version AS version,
                   rooms.creator, state.encryption, state.is_federatable AS federatable,
                   rooms.is_public AS public, state.join_rules, state.guest_access,
-                  state.history_visibility, curr.current_state_events AS state_events
+                  state.history_visibility, curr.current_state_events AS state_events,
+                  state.avatar, state.topic
                 FROM rooms
                 LEFT JOIN room_stats_state state USING (room_id)
                 LEFT JOIN room_stats_current curr USING (room_id)

tests/rest/admin/test_room.py

@@ -1174,6 +1174,8 @@ def test_single_room(self):
 
         self.assertIn("room_id", channel.json_body)
         self.assertIn("name", channel.json_body)
+        self.assertIn("topic", channel.json_body)
+        self.assertIn("avatar", channel.json_body)
         self.assertIn("canonical_alias", channel.json_body)
         self.assertIn("joined_members", channel.json_body)
         self.assertIn("joined_local_members", channel.json_body)