Shiny: insertTab with modules - module

Question

I am trying to insert tabs dynamically calling the insertTab() function within a module. For some reason my approach does not work. I guess the problem is how I pass the tabsetPanel id and the value of an existing tabPanel (next to which a tab should be added) to the module.
actionButUI = function(id, label=NULL) {
ns = NS(id)
tagList(
actionButton(ns("button"), label = label)
)
}
actionBut = function(input, output, session, tabsetPanel_id, target) {
observeEvent(input$button, {
insertTab(
inputId = tabsetPanel_id(),
tabPanel(
"Dynamic", "This a dynamically-added tab"
),
target = target
)
})
}
ui <- fluidPage(
sidebarLayout(
sidebarPanel(
actionButUI("append_tab", "Insert Tab")
),
mainPanel(
tabsetPanel(id = "tabs",
tabPanel("Hello", "This is the hello tab"),
tabPanel("Bar", "This is the bar tab")
)
)
)
)
server <- function(input, output, session) {
callModule(actionBut, "append_tab", reactive({input$tabs}), "Bar")
}
shinyApp(ui, server)

Answer 1

There seems to be an issue with namespaces. The followig modification fixes the issue
tabsetPanel(id = "append_tab-tabs",
tabPanel("Hello", "This is the hello tab"),
tabPanel("Bar", "This is the bar tab"))
The insertTab function tries to add a ui element in the module namespace rather than the global one. If you look at the source code of insertTab you'll see the line
inputId <- session$ns(inputId)
which causes this behavior.
Another way is to pass the session variable from the main app to insetTab rather than the module's session.
actionBut = function(input, output, session, tabsetPanel_id = "tabs", target) {
## do some environment hacking: Get the `session` variabe from the
## environment that invoked `callModule`.
parentSession <- get("session", envir = parent.frame(2))
observeEvent(input$button, {
insertTab(
inputId = tabsetPanel_id,
tabPanel(
"Dynamic", "This a dynamically-added tab"
),
target = target,
session = parentSession
)
})
}
This approach can get quite messy however if you work with nested modules.

Answer 2

An alternative to the InsertTab function, you can follow Ramnath solution here.
I have made it into modules.
library(shiny)
#---- Module Add dynamic tab ---
SidebarUi <- function(id) {
ns <- NS(id)
uiOutput(ns("sidebar"))
}
MainpanelUi <- function(id) {
ns <- NS(id)
uiOutput(ns("mainpanel"))
}
DynamicTabserver <- function(input, output, session) {
ns <- session$ns
output$sidebar <- renderUI({
actionButton(ns("nTabs"), label = "Add tab")
})
output$mainpanel <- renderUI({
uiOutput(ns('mytabs'))
})
output$mytabs <- renderUI({
nTabs = input$nTabs
myTabs = lapply(paste('Tab', 0:nTabs), tabPanel)
do.call(tabsetPanel, myTabs)
})
}
#---- App.R ---
ui = pageWithSidebar(headerPanel('Dynamic Tabs'),
sidebarPanel(SidebarUi("tabdemo")),
mainPanel(MainpanelUi("tabdemo")))
server = function(input, output, session) {
callModule(DynamicTabserver, "tabdemo")
}
shinyApp(ui, server)