updateQueryString: Update URL in browser's location bar

In rstudio/shiny: Web Application Framework for R

Update URL in browser's location bar

Description

This function updates the client browser's query string in the location bar. It typically is called from an observer. Note that this will not work in Internet Explorer 9 and below.

Usage

updateQueryString(
  queryString,
  mode = c("replace", "push"),
  session = getDefaultReactiveDomain()
)

Arguments

queryString	The new query string to show in the location bar.
mode	When the query string is updated, should the current history entry be replaced (default), or should a new history entry be pushed onto the history stack? The former should only be used in a live bookmarking context. The latter is useful if you want to navigate between states using the browser's back and forward buttons. See Examples.
session	A Shiny session object.

Details

For mode = "push", only three updates are currently allowed:

1. the query string (format: ?param1=val1&param2=val2)

2. the hash (format: ⁠#hash⁠)

3. both the query string and the hash (format: ?param1=val1&param2=val2#hash)

In other words, if mode = "push", the queryString must start with either ⁠?⁠ or with ⁠#⁠.

A technical curiosity: under the hood, this function is calling the HTML5 history API (which is where the names for the mode argument come from). When mode = "replace", the function called is window.history.replaceState(null, null, queryString). When mode = "push", the function called is window.history.pushState(null, null, queryString).

See Also

enableBookmarking(), getQueryString()

Examples

## Only run these examples in interactive sessions
if (interactive()) {

  ## App 1: Doing "live" bookmarking
  ## 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.
  enableBookmarking("url")
  shinyApp(
    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)
      })
    }
  )

  ## App 2: Printing the value of the query string
  ## (Use the back and forward buttons to see how the browser
  ## keeps a record of each state)
  shinyApp(
    ui = fluidPage(
      textInput("txt", "Enter new query string"),
      helpText("Format: ?param1=val1&param2=val2"),
      actionButton("go", "Update"),
      hr(),
      verbatimTextOutput("query")
    ),
    server = function(input, output, session) {
      observeEvent(input$go, {
        updateQueryString(input$txt, mode = "push")
      })
      output$query <- renderText({
        query <- getQueryString()
        queryText <- paste(names(query), query,
                       sep = "=", collapse=", ")
        paste("Your query string is:\n", queryText)
      })
    }
  )
}

rstudio/shiny documentation built on Nov. 8, 2024, 6 a.m.