Accessing the sidebar state using bs4Dash

Question

Using {shinydashboard}, we can access the state of the sidebar (collapsed or not) with input$sidebarCollapsed :

library(shiny)
library(shinydashboard)

ui <- dashboardPage(
  dashboardHeader(), 
  dashboardSidebar(),
  dashboardBody(
    textOutput("res")
  )
)

server <- function(input, output, session) {
  output$res <- renderText({
    if (input$sidebarCollapsed) {
      "Sidebar is collapsed"
    } else {
      "Sidebar is expanded"
    }
  })
}

shinyApp(ui, server)

However with {bs4dash}, this does not work :

library(shiny)
library(bs4Dash)

ui <- bs4Dash::dashboardPage(
  bs4Dash::dashboardHeader(), 
  bs4Dash::dashboardSidebar(),
  bs4Dash::dashboardBody(
    shiny::textOutput("res")
  )
)

server <- function(input, output, session) {
  output$res <- shiny::renderText({
    if (input$sidebarCollapsed) {
      "Sidebar is collapsed"
    } else {
      "Sidebar is expanded"
    }
  })
}

shinyApp(ui, server)

The app returns Error: argument is of length zero.

What am I missing ? Is there any alternative ? Accessing the sidebar state is useful for me, so that I can hide some widgets when the sidebar is minified (in order to only keep the sidebar icons visible and not widgets such as selectInputs which appear messy when minified).

I have also tried changing to sidebarMinified or some other hopeless attempts...

Note that I can also use shiny::conditionalPanel() with the condition written as 'input.sidebarCollapsed' but the result is the same.

Thanks a lot for your help !

Answer 1

I was just wondering the same thing and, upon searching the bs4Dash how-to-start guide, found the answer.

id is used by the updateSidebar() function to programmatically toggle the sidebar on the server. input$ indicates the state of the sidebar: TRUE means open and FALSE means collapsed/minified.

So, if you set the id of your sidebar to be 'my_sidebar', then you can access the state of sidebar with input$my_sidebar.