demonstration of attempt to get `conditionalPanel` to work on a file-upload condition

server.R

library(shiny)

shinyServer(function(input, output) {

  # Has a file been imported?
  output$csv_import_ready <- reactive({
    return(!is.null(input$csv_import_file))
  })
  
  # SOLUTION (2013-08-17)
  # activate the output so it runs although not displayed
  # ref: https://groups.google.com/forum/#!msg/shiny-discuss/S15Vp7P72eg/yNv_O-axrd8J
  outputOptions(output, "csv_import_ready", suspendWhenHidden = FALSE)

})

ui.R

library(shiny)

shinyUI(pageWithSidebar(
  
  # Application title
  headerPanel("Ian's very boring app"),
  
  sidebarPanel(
    
    # File Import
    fileInput(inputId="csv_import_file",
              label="Import CSV File",
              accept=c("text/csv", "text/comma-separated-values", 
                       "text/plain")),
    
    # Theory: Show this only when file has been imported
    #
    # Practice: Not shown when file has been uploaded
    conditionalPanel(
      condition="output.csv_import_ready",
      checkboxInput(inputId="do_something", label="OK, now do something!")
    )
  ),
  
  mainPanel()
))

Thanks !

I have one question, if I replace checkboxGroupInput by checkboxInput in ui.R, and I want to show that choices = names(data), selected =names(data). How could I program it, thank you.