dynamic panels

ui <- fluidPage(
    tags$script('
        Shiny.addCustomMessageHandler("toggleWellPanel",
            function(message) {
                document.getElementById(message["id"]).style.display = message["status"];
            }
        );
    '),
    fileInput('file', 'File'),
    selectInput('col_select', 'Columns', choices=c(''), multiple=TRUE),
    wellPanel(uiOutput('wellpanels'))
)


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

    data <- reactive({
        f <- input$file
        if (! is.null(f))
            read.csv(f$datapath)
    })

    observe({
        d <- data()
        if (! is.null(d))
            updateSelectInput(session, 'col_select', choices=names(d))
    })

    output$wellpanels <- renderUI({
        d <- data()
        if (! is.null(d)) {
            panels <- lapply(names(d), function(col) {
                range.col <- range(d[[col]])
                div(class='measure_well', id=paste(col, 'panel', sep='_'),
                    wellPanel(
                        sliderInput(paste(col, 'slider', sep='_'), strong(col),
                            min=range.col[1], max=range.col[2], value=range.col)
                    )
                )
            })
            #do.call(wellPanel, panels)
            #do.call(wellPanel, c(list(tags$style('.measure_well {display: none;}')), panels))
            c(list(tags$style('.measure_well {display: none;}')), panels)
        }
    })

    observe({
        d <- isolate(data())
        selected <- input$col_select
        for (col in names(d)) {
            status <- if (col %in% selected) 'block' else 'none'
            session$sendCustomMessage(type='toggleWellPanel', list(id=paste(col, 'panel', sep='_'), status=status))
        }
    })

}

runApp(list(ui=ui, server=server))