controlling shiny app page with URL variables

shiny url variables

ui <- navbarPage('TEST', id='page', collapsable=TRUE, inverse=FALSE,
    # define a message handler that will receive the variables on the client side
    # from the server and update the page accordingly.
    tags$head(tags$script("
        Shiny.addCustomMessageHandler('updateSelections',
            function(data) {
                var nav_ref = '#page a:contains(\"' + data.nav + '\")';
                var tabpanel_id = data.nav == 'Alpha' ? '#alpha_tabs' : '#beta_tabs';
                var tab_ref = tabpanel_id + ' a:contains(\"' + data.tab + '\")';
                $(nav_ref).tab('show');
                $(tab_ref).tab('show');
            }
        )
    ")),
    tabPanel('Alpha',
        tabsetPanel(id='alpha_tabs',
            tabPanel('Tab')
        )
    ),
    tabPanel('Beta',
        tabsetPanel(id='beta_tabs',
            tabPanel('Golf'),
            tabPanel('Hotel',
                selectInput("beverage", "Choose a beverage:", choices = c("Tea", "Coffee", "Cocoa"))
            )
        )
    )
)

server <- function(input, output, session) {
    observe({
        data <- parseQueryString(session$clientData$url_search)
        session$sendCustomMessage(type='updateSelections', data)
        updateSelectInput(session, 'beverage', selected=data$beverage)
    })

}

runApp(list(ui=ui, server=server), port=5678, launch.browser=FALSE)