Dynamically Created Selectinputs Not Recognized In Server

I created a simple project where I generate select inputs from a list in one module (selector) which returns the list of inputs. I have another module (viewer) which takes the inpu

Solution 1:

I've included this as a separate answer to avoid confusing the code.

This is a working version using modules and dynamic ui. note the use of ns <- session$ns within the modules. Also be careful with reactive functions. I would normally name variables rfVariableName to remind me that it is a reactive function rather than just a normal variable.

library(shiny)

# selctor Module ---------------
selectorUI <- function(id) {

  ns <- NS(id)

  uiOutput(ns("selectorPane"))

}

selector <- function(input, output, session, selection) {

  output$selectorPane <- renderUI({

    ns <- session$ns

    tagList(
      lapply(1:length(selection), function(selIdx){
        selName <- names(selection)[selIdx]
        selChoices <- selection[[selName]]
        selectInput(inputId = ns(selName), label = selName, choices = selChoices, multiple = F)
      })
    )

  })

  allInputs <- reactive({
    l <- lapply(1:length(selection), function(getid) {
      selName <- names(selection)[getid]
      input[[selName]]
    })
    names(l) <- names(selection)
    l
  })

  return(allInputs)

}

# Viewer Module ---------------
viewerUI <- function(id) {
  ns <- NS(id)

  uiOutput(ns("viewerPane"))

}

viewer <- function(input, output, session, inputValues) {

  output$viewerPane <- renderUI({

    ns <- session$ns

    if (length(inputValues()) > 0) {
      if (!is.null(inputValues()[["count"]])) {
        if (inputValues()[["count"]] > 0) {
          tagList(
            lapply(1:inputValues()[["count"]], function(idx){
              textInput(ns(paste("text",idx, sep = "_")), label = "", value = inputValues()[["colors"]])
            })
          )
        }
      }
    }

  })

}



# Main UI --------------
ui <- shinyUI(fluidPage(
  titlePanel("Sample App"),
  sidebarLayout(
    sidebarPanel(
      selectorUI("selectorModl")
    ),
    mainPanel(
      viewerUI("viewerModl")
    )
  )))


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

  selection <- list("count" = c(1,2,3,4,5), "colors" = c("blue", "green","red"))

  inputValues <- callModule(selector,"selectorModl", selection = selection)

  observeEvent(inputValues(),{

    if (length(inputValues()) > 0) {
      callModule(viewer, "viewerModl", inputValues = inputValues)
    }

  })

}

shiny::shinyApp(ui, server)

Solution 2:

There are a few approaches to creating dynamic UI in a shiny app. You have used renderUI. You could also try either insertUI or conditionalPanel. conditionalPanel is the simplest way to achieve what you want (I think). It means you don't have to worry about re-creating inputs, their associated observers and maintaining their currently selected value. conditionalPanel keeps the logic client side which means it has a snappier response and doesn't fade in/out. Example (without modules):

library(shiny)

choices_count <- c(1:10)

ui_conditional <- function(count_i) {
  conditionalPanel(condition = paste0("input.select_count >= ", count_i),
                   textOutput(paste0("text_", count_i))
      )
}

ui <- shinyUI(fluidPage(

  titlePanel("Sample app"),

  sidebarLayout(

    sidebarPanel(
      selectInput("select_count", "Count", choices = choices_count),
      selectInput("select_colour", "Colour", choices = c("blue", "green", "red"))
    ),

    mainPanel(
      lapply(choices_count, ui_conditional)
    )
  )

))

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

  observeEvent(input$select_colour, {
    for (i in choices_count) {
      output[[paste0("text_",i)]] <- renderText(input$select_colour)
    }
  })

}

shinyApp(ui, server)

Solution 3:

If I understand correctly, your issue is to understand how to generate on the server side dynamic UI components.

I tried to achieve something similar to what you have as UI example, using dynamic components.

library(shiny)

#------------------------------------------------------------------------------## Any general purpose assignment, available for any session, should be done here or on a sourced file
countLb <- c(1,2,3,4,5)
colorLb <- c("blue", "green","red")

# dynamic elements can potentially live either in a separate file, or here, or in the Server part. # Of course they need to be in Server if you change them dynamically!

dynUI <- list(
   selectInput("inputID1", label = "count",  choices = countLb, multiple = F)
 , selectInput("inputID2", label = "colors", choices = colorLb, multiple = F)
)

ui <- fluidPage(
  titlePanel("Sample App"),
  sidebarLayout(
    sidebarPanel(
      uiOutput("selectorModl")
    ),
    mainPanel(
      uiOutput("viewerModl")
    )
  ))

server = function(input, output,session) {


output$selectorModl <- renderUI({
  dynUI
})

output$viewerModl <- renderUI({

   if((length(input$inputID1) == 0) | (length(input$inputID2) == 0)) return()
   isolate({
   toRender <- lapply(1:input$inputID1, function(i) {
     textInput(paste("text",i, sep = "_"), label = "", value = input[["inputID2"]])
   })
   return(toRender)
   }) # end isolate
 })
}

shinyApp(ui,server)

Please let me know if I got close to address your requirements, of if you need any further clarification on this code.