Get the query string / hash component from the URL — getQueryString

v1.7.2|Source: R/history.R

Description

Two user friendly wrappers for getting the query string and the hash component from the app's URL.

getQueryString(session = getDefaultReactiveDomain())

getUrlHash(session = getDefaultReactiveDomain())

Arguments

session

A Shiny session object.

Value

For getQueryString, a named list. For example, the query string ?param1=value1&param2=value2 becomes list(param1 = value1, param2 = value2). For getUrlHash, a character vector with the hash (including the leading # symbol).

Details

These can be particularly useful if you want to display different content depending on the values in the query string / hash (e.g. instead of basing the conditional on an input or a calculated reactive, you can base it on the query string). However, note that, if you're changing the query string / hash programatically from within the server code, you must use updateQueryString(_yourNewQueryString_, mode = "push"). The default mode for updateQueryString is "replace", which doesn't raise any events, so any observers or reactives that depend on it will not get triggered. However, if you're changing the query string / hash directly by typing directly in the browser and hitting enter, you don't have to worry about this.

See also

updateQueryString()

Examples

## Only run this example in interactive R sessions
if (interactive()) {

  ## App 1: getQueryString
  ## 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)
      })
    }
  )

  ## App 2: getUrlHash
  ## Printing the value of the URL hash
  ## (Use the back and forward buttons to see how the browser
  ## keeps a record of each state)
  shinyApp(
    ui = fluidPage(
      textInput("txt", "Enter new hash"),
      helpText("Format: #hash"),
      actionButton("go", "Update"),
      hr(),
      verbatimTextOutput("hash")
    ),
    server = function(input, output, session) {
      observeEvent(input$go, {
        updateQueryString(input$txt, mode = "push")
      })
      output$hash <- renderText({
        hash <- getUrlHash()
        paste("Your hash is:\n", hash)
      })
    }
  )
}