Follow threads without memberships if marked as unread (#17800)

app/user.go

@@ -2245,10 +2245,16 @@ func (a *App) UpdateThreadReadForUser(userID, teamID, threadID string, timestamp
 	if err != nil {
 		return nil, err
 	}
-	membership, nErr := a.Srv().Store.Thread().GetMembershipForUser(userID, threadID)
-	if nErr != nil {
-		return nil, model.NewAppError("UpdateThreadsReadForUser", "app.user.update_threads_read_for_user.app_error", nil, nErr.Error(), http.StatusInternalServerError)
+
+	opts := store.ThreadMembershipOpts{
+		Following:       true,
+		UpdateFollowing: false,
 	}
+	membership, storeErr := a.Srv().Store.Thread().MaintainMembership(userID, threadID, opts)
+	if storeErr != nil {
+		return nil, model.NewAppError("UpdateThreadReadForUser", "app.user.update_thread_read_for_user.app_error", nil, err.Error(), http.StatusInternalServerError)
+	}
+
 	post, err := a.GetSinglePost(threadID)
 	if err != nil {
 		return nil, err
@@ -2258,9 +2264,9 @@ func (a *App) UpdateThreadReadForUser(userID, teamID, threadID string, timestamp
 		return nil, err
 	}
 	membership.Following = true
-	_, nErr = a.Srv().Store.Thread().UpdateMembership(membership)
+	_, nErr := a.Srv().Store.Thread().UpdateMembership(membership)
 	if nErr != nil {
-		return nil, model.NewAppError("UpdateThreadsReadForUser", "app.user.update_threads_read_for_user.app_error", nil, nErr.Error(), http.StatusInternalServerError)
+		return nil, model.NewAppError("UpdateThreadReadForUser", "app.user.update_thread_read_for_user.app_error", nil, nErr.Error(), http.StatusInternalServerError)
 	}
 
 	membership.LastViewed = timestamp