using renderUI based input in a Shiny Module

.r

library(shiny)
library(ggplot2)

# module UI function
scatterOuput <- function(id){

  ns <- NS(id)

  tagList(

    br(),

    fluidRow(
      column(6,
         # dynamic controls to select x and y in plot1, to be rendered via server
         uiOutput(ns("dynamicControls")),

         # plot 1
         plotOutput(ns("plot1"))
      ),
      column(6,

         # dynamic controls to select x and y in plot2
         fluidRow(
           column(offset = 2, 4,
                  selectInput(ns("x2"),"x2",choices = names(mtcars), width = "100%")
           ),
           column(4,
                  selectInput(ns("y2"),"y2",choices = names(mtcars), width = "100%")
           )
         ),

         # plot 2
         plotOutput(ns("plot2"))
      )
    )
  )
}
# module server function
scatter <- function(input, output, session, data) {

  # set data
  data <- mtcars

  # dynamic controls
  output$dynamicControls <- renderUI({
    tagList(
      fluidRow(
        column(offset = 2, 4,
               selectInput("x1","x1",choices = names(mtcars), width = "100%")
        ),
        column(4,
               selectInput("y1","y1",choices = names(mtcars), width = "100%")
        )
      )
    )
  })

  # plot 1
  output$plot1 <- renderPlot({
    scatterPlot(data, c(input$x1,input$y1))
    #scatterPlot(data, c("mpg","disp"))
  })

  # plot2
  output$plot2 <- renderPlot({
    scatterPlot(data, c(input$x2,input$y2))
  })
}

# plot helper function
scatterPlot <- function(data, cols) {
  ggplot(data, aes_string(x = cols[1], y = cols[2])) + geom_point()
}

# main ui
ui <- fixedPage(
  scatterOuput("id1")
)

# main server
server <- function(input, output, session) {
  callModule(scatter, "id1", data = mtcars)
}

# run app
shinyApp(ui, server)

thanks for the snippet, the dynamically rendered UI no longer seems to work on Shiny though (I have 1.0.0)...any ideas on how to fix?

@cmdcolin:

As I learned from Joe Cheng's article on RStudio, wrap the id attributes of the selectInputs in the renderUI call with the session namespace assigned at the top of the server module function:

---

**ns <- session$ns**

  output$dynamicControls <- renderUI({
    tagList(
      fluidRow(
        column(offset = 2, 4,
               selectInput(**ns("x1")** ,"x1",choices = names(mtcars), width = "100%")
        ),
        column(4,
               selectInput(**ns("y1")** ,"y1",choices = names(mtcars), width = "100%")
        )
      )
    )
  })

(I've had namespace problems when rendering datatables in module server functions, too,)

BTW, to get rid of red error message that flashes before plot #1 is displayed, modify output$plot1 ...

output$plot1 <- renderPlot({

 **req(input$x1, input$y1, cancelOutput = T)**

  scatterPlot(data, c(input$x1,input$y1))
  #scatterPlot(data, c("mpg","disp"))
})