Conversations: Fetch users in one query.

lib/pleroma/conversation/participation.ex

@@ -59,10 +59,10 @@ def mark_as_unread(participation) do
   def for_user(user, params \\ %{}) do
     from(p in __MODULE__,
       where: p.user_id == ^user.id,
-      order_by: [desc: p.updated_at]
+      order_by: [desc: p.updated_at],
+      preload: [conversation: [:users]]
     )
     |> Pleroma.Pagination.fetch_paginated(params)
-    |> Repo.preload(conversation: [:users])
   end
 
   def for_user_with_last_activity_id(user, params \\ %{}) do

test/conversation/participation_test.exs

@@ -72,8 +72,11 @@ test "gets all the participations for a user, ordered by updated at descending"
     object2 = Pleroma.Object.normalize(activity_two)
     object3 = Pleroma.Object.normalize(activity_three)
 
+    user = Repo.get(Pleroma.User, user.id)
+
     assert participation_one.conversation.ap_id == object3.data["context"]
     assert participation_two.conversation.ap_id == object2.data["context"]
+    assert participation_one.conversation.users == [user]
 
     # Pagination
     assert [participation_one] = Participation.for_user(user, %{"limit" => 1})