MM-35206 CRT: is_following on posts not reflecting state properly (#17533)

* forgot to copy isFollowing param

* /thread API didn't return thread posts, just the root

* cleanup

* [ci]

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

model/post.go

@@ -207,6 +207,7 @@ func (o *Post) ShallowCopy(dst *Post) error {
 	dst.Participants = o.Participants
 	dst.LastReplyAt = o.LastReplyAt
 	dst.Metadata = o.Metadata
+	dst.IsFollowing = o.IsFollowing
 	dst.RemoteId = o.RemoteId
 	return nil
 }

store/sqlstore/post_store.go

@@ -474,7 +474,22 @@ func (s *SqlPostStore) getPostWithCollapsedThreads(id, userID string, extended b
 
 		return nil, errors.Wrapf(err, "failed to get Post with id=%s", id)
 	}
-	return s.prepareThreadedResponse([]*postWithExtra{&post}, extended, false)
+
+	var posts []*model.Post
+	_, err = s.GetReplica().Select(&posts, "SELECT * FROM Posts WHERE Posts.RootId = :RootId AND DeleteAt = 0", map[string]interface{}{"RootId": id})
+	if err != nil {
+		return nil, errors.Wrapf(err, "failed to find Posts for thread %s", id)
+	}
+
+	list, err := s.prepareThreadedResponse([]*postWithExtra{&post}, extended, false)
+	if err != nil {
+		return nil, err
+	}
+	for _, p := range posts {
+		list.AddPost(p)
+		list.AddOrder(p.Id)
+	}
+	return list, nil
 }
 
 func (s *SqlPostStore) Get(ctx context.Context, id string, skipFetchThreads, collapsedThreads, collapsedThreadsExtended bool, userID string) (*model.PostList, error) {