shiny (version 1.4.0)

enableBookmarking: Enable bookmarking for a Shiny application

Description

There are two types of bookmarking: saving an application's state to disk on the server, and encoding the application's state in a URL. For state that has been saved to disk, the state can be restored with the corresponding state ID. For URL-encoded state, the state of the application is encoded in the URL, and no server-side storage is needed.

URL-encoded bookmarking is appropriate for applications where there not many input values that need to be recorded. Some browsers have a length limit for URLs of about 2000 characters, and if there are many inputs, the length of the URL can exceed that limit.

Saved-on-server bookmarking is appropriate when there are many inputs, or when the bookmarked state requires storing files.

Usage

enableBookmarking(store = c("url", "server", "disable"))

Arguments

store

Either "url", which encodes all of the relevant values in a URL, "server", which saves to disk on the server, or "disable", which disables any previously-enabled bookmarking.

Details

For restoring state to work properly, the UI must be a function that takes one argument, request. In most Shiny applications, the UI is not a function; it might have the form fluidPage(....). Converting it to a function is as simple as wrapping it in a function, as in function(request) { fluidPage(....) }.

By default, all input values will be bookmarked, except for the values of passwordInputs. fileInputs will be saved if the state is saved on a server, but not if the state is encoded in a URL.

When bookmarking state, arbitrary values can be stored, by passing a function as the onBookmark argument. That function will be passed a ShinySaveState object. The values field of the object is a list which can be manipulated to save extra information. Additionally, if the state is being saved on the server, and the dir field of that object can be used to save extra information to files in that directory.

For saved-to-server state, this is how the state directory is chosen:

• If running in a hosting environment such as Shiny Server or Connect, the hosting environment will choose the directory.

• If running an app in a directory with runApp(), the saved states will be saved in a subdirectory of the app called shiny_bookmarks.

• If running a Shiny app object that is generated from code (not run from a directory), the saved states will be saved in a subdirectory of the current working directory called shiny_bookmarks.

When used with shinyApp(), this function must be called before shinyApp(), or in the shinyApp()'s onStart function. An alternative to calling the enableBookmarking() function is to use the enableBookmarking argument for shinyApp(). See examples below.

See Also

onBookmark(), onBookmarked(), onRestore(), and onRestored() for registering callback functions that are invoked when the state is bookmarked or restored.

Also see updateQueryString().

Examples

# NOT RUN {
## Only run these examples in interactive R sessions
if (interactive()) {

# Basic example with state encoded in URL
ui <- function(request) {
  fluidPage(
    textInput("txt", "Text"),
    checkboxInput("chk", "Checkbox"),
    bookmarkButton()
  )
}
server <- function(input, output, session) { }
enableBookmarking("url")
shinyApp(ui, server)


# An alternative to calling enableBookmarking(): use shinyApp's
# enableBookmarking argument
shinyApp(ui, server, enableBookmarking = "url")


# Same basic example with state saved to disk
enableBookmarking("server")
shinyApp(ui, server)


# Save/restore arbitrary values
ui <- function(req) {
  fluidPage(
    textInput("txt", "Text"),
    checkboxInput("chk", "Checkbox"),
    bookmarkButton(),
    br(),
    textOutput("lastSaved")
  )
}
server <- function(input, output, session) {
  vals <- reactiveValues(savedTime = NULL)
  output$lastSaved <- renderText({
    if (!is.null(vals$savedTime))
      paste("Last saved at", vals$savedTime)
    else
      ""
  })

  onBookmark(function(state) {
    vals$savedTime <- Sys.time()
    # state is a mutable reference object, and we can add arbitrary values
    # to it.
    state$values$time <- vals$savedTime
  })
  onRestore(function(state) {
    vals$savedTime <- state$values$time
  })
}
enableBookmarking(store = "url")
shinyApp(ui, server)


# Usable with dynamic UI (set the slider, then change the text input,
# click the bookmark button)
ui <- function(request) {
  fluidPage(
    sliderInput("slider", "Slider", 1, 100, 50),
    uiOutput("ui"),
    bookmarkButton()
  )
}
server <- function(input, output, session) {
  output$ui <- renderUI({
    textInput("txt", "Text", input$slider)
  })
}
enableBookmarking("url")
shinyApp(ui, server)


# Exclude specific inputs (The only input that will be saved in this
# example is chk)
ui <- function(request) {
  fluidPage(
    passwordInput("pw", "Password"), # Passwords are never saved
    sliderInput("slider", "Slider", 1, 100, 50), # Manually excluded below
    checkboxInput("chk", "Checkbox"),
    bookmarkButton()
  )
}
server <- function(input, output, session) {
  setBookmarkExclude("slider")
}
enableBookmarking("url")
shinyApp(ui, server)


# Update the browser's location bar every time an input changes. This should
# not be used with enableBookmarking("server"), because that would create a
# new saved state on disk every time the user changes an input.
ui <- function(req) {
  fluidPage(
    textInput("txt", "Text"),
    checkboxInput("chk", "Checkbox")
  )
}
server <- function(input, output, session) {
  observe({
    # Trigger this observer every time an input changes
    reactiveValuesToList(input)
    session$doBookmark()
  })
  onBookmarked(function(url) {
    updateQueryString(url)
  })
}
enableBookmarking("url")
shinyApp(ui, server)


# Save/restore uploaded files
ui <- function(request) {
  fluidPage(
    sidebarLayout(
      sidebarPanel(
        fileInput("file1", "Choose CSV File", multiple = TRUE,
          accept = c(
            "text/csv",
            "text/comma-separated-values,text/plain",
            ".csv"
          )
        ),
        tags$hr(),
        checkboxInput("header", "Header", TRUE),
        bookmarkButton()
      ),
      mainPanel(
        tableOutput("contents")
      )
    )
  )
}
server <- function(input, output) {
  output$contents <- renderTable({
    inFile <- input$file1
    if (is.null(inFile))
      return(NULL)

    if (nrow(inFile) == 1) {
      read.csv(inFile$datapath, header = input$header)
    } else {
      data.frame(x = "multiple files")
    }
  })
}
enableBookmarking("server")
shinyApp(ui, server)

}
# }