shiny/man/getQueryString.Rd

% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/history.R
\name{getQueryString}
\alias{getQueryString}
\alias{getUrlHash}
\title{Get the query string / hash component from the URL}
\usage{
getQueryString(session = getDefaultReactiveDomain())

getUrlHash(session = getDefaultReactiveDomain())
}
\arguments{
\item{session}{A Shiny session object.}
}
\value{
For \code{getQueryString}, a named list. For example, the query
string \code{?param1=value1&param2=value2} becomes \code{list(param1 = value1, param2 = value2)}. For \code{getUrlHash}, a character vector with
the hash (including the leading \verb{#} symbol).
}
\description{
Two user friendly wrappers for getting the query string and the hash
component from the app's URL.
}
\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
programmatically from within the server code, you must use
\verb{updateQueryString(_yourNewQueryString_, mode = "push")}. The default
\code{mode} for \code{updateQueryString} is \code{"replace"}, which doesn't
raise any events, so any observers or reactives that depend on it will
\emph{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.
}
\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)
      })
    }
  )
}
}
\seealso{
\code{\link[=updateQueryString]{updateQueryString()}}
}