Observe an input which rendered in uiOutput in a module

December 16, 2023

I am trying to observe an input which rendered in uiOutput in a module.

I tried the following reprex code:

my_modUI <- function(id) {
  ns <- NS(id)
  tagList(
  uiOutput(ns("ui1")),
  verbatimTextOutput(ns("text1"))
  )
}

my_modServer <- function(id) {
  moduleServer(
    id,
    function(input, output, session) {
      output$ui1 <- renderUI({
        actionButton("btn", "Click me!")
      })
      
      observeEvent(input$btn, handlerExpr = {
        output$text1 <- renderPrint(paste0("Button is clicked"))
      })
    }
  )
}

library(shiny)

ui <- fluidPage(
  my_modUI("my_mod")
)

server <- function(input, output, session) {
  my_modServer("my_mod")
}

shinyApp(ui, server)

It didn’t work. What I am expecting to see is this

Could you help me to solve this problems with using Shiny modules.

>Solution :

As you are in a module you need to wrap the button id in ns() for which you can use the session$ns. See the part on using renderUI in a module at https://shiny.posit.co/r/articles/improve/modules/:

my_modUI <- function(id) {
  ns <- NS(id)
  tagList(
    uiOutput(ns("ui1")),
    verbatimTextOutput(ns("text1"))
  )
}

my_modServer <- function(id) {
  moduleServer(
    id,
    function(input, output, session) {
      output$ui1 <- renderUI({
        ns <- session$ns
        
        actionButton(ns("btn"), "Click me!")
      })

      observeEvent(input$btn, handlerExpr = {
        output$text1 <- renderPrint(paste0("Button is clicked"))
      })
    }
  )
}

library(shiny)

ui <- fluidPage(
  my_modUI("my_mod")
)

server <- function(input, output, session) {
  my_modServer("my_mod")
}

shinyApp(ui, server)