How to dynamically generate Shiny sidebarPanel contents?

Question

I'm trying to create an app where the user is initially presented with a sidebar selectInput containing a list of choices: A, B, C and D – populated by file-system contents.

Depending on which choice the user selects, I want to populate the rest of the sidebar with choice-specific contents. For example, if the user chooses "A", then the sidebar will contain an additional selectInput and dateRangeInput .

To keep the code clean, I've kept all "A"-specific code in handle_A.R , etc. This means that eventually when I decide to add a new choice "E", I just need to put all the code in handle_E.R .

ui.R

pageWithSidebar(
  headerPanel("Test"),
  sidebarPanel(
    selectizeInput("choice", "Choice:", c()),
    uiOutput("sidebar")
  ),
  mainPanel(uiOutput("main"))
)

server.R (relevant bits)

output$sidebar <- renderUI({
  sidebarRenderer[[input$choice]](input, output, session)
})

I have code in server.R that sources all the handle_*.R scripts – each registering their callbacks.

So far, so good. I can select various choices and the relevant callbacks are called. However, I don't know how to implement the callbacks such that I can update the sidebar widgets as the user interacts with the sidebar. I want to essentially do the following (which will not work, because the function needs to return something to renderUI ):

handle_A.R

sidebarRenderer[["A"]] <<- function(input, output, session) {
  selectInput("day", "Day:", c("Mon", "Wed", "Fri"))
  dates <- getDateList(input$day)
  dateRangeInput("date", "Date:", start=dates[0], end=dates[length(dates)])
  if (hasPublicHoliday(dates))
    checkboxInput("ignoreHolidays", "Ignore public holidays")
}

So what I want is to automatically update dateRangeInput to the calculated start and end dates for the corresponding Mon/Wed/Fri. Furthermore, if any of the dates contain a public holiday, I want to display an extra checkbox to let the user ignore public holidays.

If anybody can help me out, I'd greatly appreciate it!

Answer 1

事实证明，我所需要的只是将逻辑放入observe并调用updateCheckBoxInput 。