Removing from tabsetpanel a panel defined inside a module (need to try twice to recreate a removed tab)

Question

Im trying to build a simple app with a tabsetPanel having a set of panels definded inside a module, each one of these panels has an actionbutton aimed to remove the panel.

It seems to work, but if I try to recreate a tab with the same name of the one I already deleted, I need to click twice "Add Panel" (2nd app below)

This problem doesn't happen if I build the same kind of application but with no module (1st app in the code section)

Anyone is having an explanation or suggestion to fix this behaviour?

Below the two app versions. Many thanks for any insight Paolo

VERSION WITHOUT MODULE

1. Put a name in "Panel Name" textinput
2. Click "Add Panel"
3. Click "Remove Panel"
4. Keep in textinput the existing name
5. Click "Add Panel" ...the tab is added again

VERSION WITH MODULE

1. Put a name in Panel Name textinput
2. Click "Add Panel"
3. From inside the added panel Click "remove"
4. Keep in "Panel Name" the existing name
5. Click "Add Panel" ...nothing happens (I need to click a second time "Add Panel")

If at point 4) I change the name which has never been used, then a new panel is added without clicking twice "Add Panel"

Decomment in RUNAPP section the version to run

# ==================================================================
# VERSION WITHOUT MODULE 
# ==================================================================

ui <- fluidPage(
  actionButton(inputId = 'addpanel', 'Add Panel'),
  actionButton(inputId = 'delpanel', 'Remove Panel'),
  textInput('panelName', 'Panel Name'),
  textOutput('panelList'),
  tabsetPanel(id = 'panel_set')
)


server <- function(input, output, session) {

  panelsetName <- 'panel_set'
  tab_list_reactive <- reactiveValues(names=NULL)

  observeEvent(input$addpanel,{
    appendTab(inputId = panelsetName, tab = tabPanel(title = input$panelName))
    tab_list_reactive$names <- c(tab_list_reactive$names, input$panelName)
  })

  observeEvent(input$delpanel,{
    removeTab(inputId = panelsetName, target = input$panelName)
    tab_list_reactive$names <- tab_list_reactive$names[-which(tab_list_reactive$names == input$panelName)]
  })

  output$panelList <- renderText(tab_list_reactive$names)
}




# ==================================================================
# VERSION WITH MODULE 
# ==================================================================

ui_withModule <- fluidPage(
  actionButton(inputId = 'addpanel', 'Add Panel'),
  textInput('panelName', 'Panel Name'),
  textOutput('panelList'),
  tabsetPanel(id = 'panel_set')
)


server_withModule <- function(input, output, session) {

  tab_list_reactive <- reactiveValues(names=NULL)
  panelsetName <- 'panel_set'

  observeEvent(input$addpanel,{
    appendTab(inputId = panelsetName, tab = tabPanel(title = input$panelName, panel_module_ui(id = input$panelName)))

    callModule(module = panel_module_server, id = input$panelName, nometabset = panelsetName,
               tab_title = input$panelName, parentSession = session, tab_list_reactive = tab_list_reactive)
  })

  output$panelList <- renderText(tab_list_reactive$names)
}


# MODULE -------------------------------------------------------
panel_module_ui <- function(id){
  tabPanel(title = id, {actionButton(NS(id, 'removetab'), label = 'remove')})
}

panel_module_server <- function(input, output, session, nometabset, tab_title, tab_list_reactive, parentSession) {
  tab_list_reactive$names <- c(tab_list_reactive$names, tab_title)

  observeEvent(input[['removetab']], {
    removeTab(nometabset, tab_title, session = parentSession)
    tab_list_reactive$names <- tab_list_reactive$names[ tab_list_reactive$names != tab_title]
  })
}



# ==================================================================
# RUN APP 
# ==================================================================

#shinyApp(ui, server)
shinyApp(ui_withModule, server_withModule)

Answer 1

For anyone with the same problem, I found a post of Harvey Lieberman giving an elegant solution (each tab label has a clickable "x" to close the tab) https://www.harveyl888.com/post/2022-01-01-dynamic_tabs/

Paolo

# UI
ui_withModule <- fluidPage(
  actionButton(inputId = 'addpanel', 'Add Panel'),
  textInput('panelName', 'Panel Name'),
  textOutput('panelList'),
  tabsetPanel(id = 'panel_set')
)

# SERVER
server_withModule <- function(input, output, session) {

  tab_list_reactive <- reactiveValues(names=NULL)
  panelsetName <- 'panel_set'

  observeEvent(input$addpanel,{
    appendTab(inputId = panelsetName, tab = tabPanel(title = tab_title(input$panelName), value = input$panelName, panel_module_ui(id = input$panelName)))


    callModule(module = panel_module_server, id = input$panelName, nometabset = panelsetName,
               tab_title = input$panelName, parentSession = session, tab_list_reactive = tab_list_reactive)
  })


  observe({
    shinydashboard::updateTabItems(session = session, inputId = panelsetName, selected = NULL)
  })

  output$panelList <- renderText(tab_list_reactive$names)

  observeEvent(input$remove_data_tab, {
    removeTab(inputId = "panel_set", target = input$panelName)
    isolate({tab_list_reactive$names <- tab_list_reactive$names[!tab_list_reactive$names == input$panelName]})
  })

}


# MODULE ------------------------------------------------------------
panel_module_ui <- function(id){
  tabPanel(title = id, {})
}

panel_module_server <- function(input, output, session, nometabset, tab_title, tab_list_reactive, parentSession) {
  tab_list_reactive$names <- c(tab_list_reactive$names, tab_title)

}

# HARVEY TRICK ------------------------------------------------------------
tab_title <- function(name, type = "data") {
  tags$span(
    name,
    tags$span(icon("times"),
              style = "margin-left: 5px;",
              onclick = paste0("Shiny.setInputValue(\"", paste0("remove_", type, "_tab"), "\", \"", name, "\", {priority: \"event\"})"))
  )
}


# RUN APP 
shinyApp(ui_withModule, server_withModule)