MM-26753 Create initial sidebar categories on demand if migration hasn't ran (#14981)

* MM-26753 Change CreateInitialSidebarCategories to only take a user ID

* MM-26753 Create initial sidebar categories on demand if migration hasn't ran

* Wait for sidebar categories to be loaded in case of replication lag

app/channel.go

@@ -2603,8 +2603,8 @@ func (a *App) ClearChannelMembersCache(channelID string) {
 	}
 }
 
-func (a *App) createInitialSidebarCategories(user *model.User, team *model.Team) *model.AppError {
-	nErr := a.Srv().Store.Channel().CreateInitialSidebarCategories(user, team.Id)
+func (a *App) createInitialSidebarCategories(userId, teamId string) *model.AppError {
+	nErr := a.Srv().Store.Channel().CreateInitialSidebarCategories(userId, teamId)
 
 	if nErr != nil {
 		return model.NewAppError("createInitialSidebarCategories", "app.channel.create_initial_sidebar_categories.internal_error", nil, nErr.Error(), http.StatusInternalServerError)
@@ -2614,7 +2614,45 @@ func (a *App) createInitialSidebarCategories(user *model.User, team *model.Team)
 }
 
 func (a *App) GetSidebarCategories(userId, teamId string) (*model.OrderedSidebarCategories, *model.AppError) {
-	return a.Srv().Store.Channel().GetSidebarCategories(userId, teamId)
+	categories, err := a.Srv().Store.Channel().GetSidebarCategories(userId, teamId)
+
+	if len(categories.Categories) == 0 && err == nil {
+		// A user must always have categories, so migration must not have happened yet, and we should run it ourselves
+		nErr := a.createInitialSidebarCategories(userId, teamId)
+		if nErr != nil {
+			return nil, nErr
+		}
+
+		categories, err = a.waitForSidebarCategories(userId, teamId)
+	}
+
+	return categories, err
+}
+
+// waitForSidebarCategories is used to get a user's sidebar categories after they've been created since there may be
+// replication lag if any database replicas exist. It will wait until results are available to return them.
+func (a *App) waitForSidebarCategories(userId, teamId string) (*model.OrderedSidebarCategories, *model.AppError) {
+	if len(a.Config().SqlSettings.DataSourceReplicas) == 0 {
+		// The categories should be available immediately on a single database
+		return a.Srv().Store.Channel().GetSidebarCategories(userId, teamId)
+	}
+
+	now := model.GetMillis()
+
+	for model.GetMillis()-now < 12000 {
+		time.Sleep(100 * time.Millisecond)
+
+		categories, err := a.Srv().Store.Channel().GetSidebarCategories(userId, teamId)
+
+		if err != nil || len(categories.Categories) > 0 {
+			// We've found something, so return
+			return categories, err
+		}
+	}
+
+	mlog.Error("waitForSidebarCategories giving up", mlog.String("user_id", userId), mlog.String("team_id", teamId))
+
+	return &model.OrderedSidebarCategories{}, nil
 }
 
 func (a *App) GetSidebarCategoryOrder(userId, teamId string) ([]string, *model.AppError) {

app/channel_test.go

@@ -1858,3 +1858,42 @@ func TestSidebarCategory(t *testing.T) {
 		require.Equal(t, catOrder[1], createdCategory.Id, "the newly created category should be after favorites")
 	})
 }
+
+func TestGetSidebarCategories(t *testing.T) {
+	t.Run("should return the sidebar categories for the given user/team", func(t *testing.T) {
+		th := Setup(t).InitBasic()
+		defer th.TearDown()
+
+		_, err := th.App.CreateSidebarCategory(th.BasicUser.Id, th.BasicTeam.Id, &model.SidebarCategoryWithChannels{
+			SidebarCategory: model.SidebarCategory{
+				UserId:      th.BasicUser.Id,
+				TeamId:      th.BasicTeam.Id,
+				DisplayName: "new category",
+			},
+		})
+		require.Nil(t, err)
+
+		categories, err := th.App.GetSidebarCategories(th.BasicUser.Id, th.BasicTeam.Id)
+		assert.Nil(t, err)
+		assert.Len(t, categories.Categories, 4)
+	})
+
+	t.Run("should create the initial categories even if migration hasn't ran yet", func(t *testing.T) {
+		th := Setup(t).InitBasic()
+		defer th.TearDown()
+
+		// Manually add the user to the team without going through the app layer to simulate a pre-existing user/team
+		// relationship that hasn't been migrated yet
+		team := th.CreateTeam()
+		_, err := th.App.Srv().Store.Team().SaveMember(&model.TeamMember{
+			TeamId:     team.Id,
+			UserId:     th.BasicUser.Id,
+			SchemeUser: true,
+		}, 100)
+		require.Nil(t, err)
+
+		categories, err := th.App.GetSidebarCategories(th.BasicUser.Id, team.Id)
+		assert.Nil(t, err)
+		assert.Len(t, categories.Categories, 3)
+	})
+}

app/team.go

@@ -653,7 +653,7 @@ func (a *App) JoinUserToTeam(team *model.Team, user *model.User, userRequestorId
 		return err
 	}
 
-	if err := a.createInitialSidebarCategories(user, team); err != nil {
+	if err := a.createInitialSidebarCategories(user.Id, team.Id); err != nil {
 		mlog.Error(
 			"Encountered an issue creating default sidebar categories.",
 			mlog.String("user_id", user.Id),