R Shiny: Issue passing reactive values to module

Question

This should be pretty easy, but it is not working as I would expect it to. All I am trying to do is get "first light" in passing reactive elements from main server function to a module. The point of this toy example is simple: user types anything in a textInput() box and that value gets displayed in two verbatimTextOutput() boxes, one from the main server, one called in the module server. I am looking for both boxes to display what the user types in, but the module box does not. This tells me that the module is not properly receiving the parameter, and I do not see my mistake. Thanks!

library(shiny)

ui <- function(request) {
    fluidPage(
        column(12, textInput("par", "Parameter", value = "")),
        column(12, parametersMDUI(0)),
        column(12, verbatimTextOutput("view", placeholder = TRUE))
          )
}

server <- function(input, output, session) {
    param <- reactive({ input$par })
    callModule(parametersMDServer, 0, param)
    output$view <- renderText({ param() })
}


parametersMDUI <- function(id) {
    ns <- NS(id)

    tags$div(
        column(12, verbatimTextOutput("symbolName", placeholder = TRUE)),
        id = ns('parametersMDui')
    )
}


parametersMDServer <- function(input, output, session, param) {
    ns = session$ns

    output$symbolName <- renderText({ param })
}

shinyApp(ui = ui, server = server, enableBookmarking = "server")

Answer 1

It seems like you use tags$div(..., id = "my_output_id") in your code and then try to access the div with renderUI ? This won't work. Use the "standard"

# server side
output$my_output_id <- renderUI({ ... })

# client side
uiOutput("my_output_id")

instead. Apart from that, you forgot to use the ns function in parametersMDUI . I will not post any fixed versions of your code anymore since your errors start to repeat and you really need to be able to spot them yourself.