how to preload tabs in tabsetpanel???

[Caveman Pl]

Hi All,

Here is the minimal working example which perfectly describes my problem. Just module inside of module which adds tabs to tabsetPanel.
Please tell me why appendTab works only inside of observeEvent . why when I'm trying preload (line 53) one tab when moduleB_server is launched it do nothing.

Thank you,
tj

library(shiny)
library(shinydashboard)


moduleC_ui <- function(id) {
  ns <- NS(id)
  fluidPage(
    fluidRow(
      verbatimTextOutput(ns("saveString"))
    ),
    fluidRow(
      hr(style = "border-top: 1px solid #000000;")
    ),
    fluidRow(
      actionButton(ns("save"), "Save"),    
    )
  )
}


moduleC_server <- function(id) {
  moduleServer(id, function(input, output, session) {
    observeEvent(input$save,{
      output$saveString <- renderPrint({
        "saving..."
      })
    })
  })
}


moduleB_ui<- function(id) {
  ns <- NS(id)
  fluidPage(

    fluidRow(
      actionButton(ns("addTab"), "Add Tab"),

      tabsetPanel(id = ns("moduleB"))

    )
  )
 
}


moduleB_server <- function(id) {
  moduleServer(id, function(input, output, session) {
   
    ns <- session$ns
    localVariables = reactiveValues(tabCounter = 2, tabsServers=list())  

    appendTab("moduleB", tabPanel("moduleC_tab_1", moduleC_ui(ns("moduleC_tab_1"))), select = TRUE)
    localVariables$tabsServers[["moduleC_tab_1"]] <- moduleC_server("moduleC_tab_1")

    observeEvent(input$addTab, {
        newTabName <- paste0("moduleC_tab_",localVariables$tabCounter)
        localVariables$tabCounter = localVariables$tabCounter+1
        appendTab("moduleB", tabPanel(newTabName, moduleC_ui(ns(newTabName))), select = TRUE)
        localVariables$tabsServers[[newTabName]] <- moduleC_server(newTabName)
    })
   
  })
 
}


moduleA_ui <- function(id) {
  ns <- NS(id)
  tabsetPanel(
    id = ns("tabsetPanelID"),
    tabPanel("moduleA_tab1",
             fluidRow(
               column(width = 12,
                      hr(style = "border-top: 1px solid #000000;"),
                      uiOutput(ns("layout_b"))
               )
             )    
    ),
    tabPanel("moduleA_tab1")
  )
 
 
}


moduleA_server <- function(id) {
  moduleServer(
    id,
    function(input,output,session){
     
      output$layout_b<-renderUI({
        ns <- session$ns
        moduleB_ui(ns("moduleB_tab"))
      })
     
      moduleB_server(id = "moduleB_tab")
     
    }
  )
}


ui <- dashboardPage(
  dashboardHeader(title = "tabs preload example"),
  dashboardSidebar(sidebarMenuOutput("menu")),
  dashboardBody(tabItems(
    tabItem(tabName = "tab_1", moduleA_ui("moduleA"))

  ))
)


server <- function(input, output) {


  observeEvent(input$tabs,{
    if(input$tabs=="tab_1"){
      moduleA_server(id = "moduleA")

    }
  }, ignoreNULL = TRUE, ignoreInit = TRUE)
 
 
  output$menu <- renderMenu({
    sidebarMenu(id = "tabs",
                menuItem(
                  "moduleA",
                  icon = icon("calendar"),
                  tabName = "tab_1"
                )
    )
  })
}


shinyApp(ui, server)