How to set up an event which expands a bslib card?

Question

I would like to expand a bslib card in a shiny app from the server. Here is a minimal example:

library(shiny)
library(bslib)

ui <- bslib::page_fluid(
  actionButton("go", "GO"),
  bslib::card(
    h1("Hello"),
    full_screen = TRUE
    )
)

server <- function(input, output, session){
  observe({
    # some code to expand the card 
  }) |> 
    bindEvent(input$go)
}

shinyApp(ui, server)

Answer 1

You can use session$sendCustomMessage and a handler which simulates a click on the "Expand" button:

library(shiny)
library(bslib)

ui <- bslib::page_fluid(
  tags$head(tags$script(HTML(
    "Shiny.addCustomMessageHandler('expand',",
    "  function(message) {",
    "    $('#' + message.id + ' > bslib-tooltip > button').click();",
    "  }",
    ");"))),
  actionButton("go", "GO"),
  bslib::card(
    id = "my_card",
    h1("Hello"),
    full_screen = TRUE
  )
)

server <- function(input, output, session){
  observeEvent(input$go, {
    session$sendCustomMessage(type = 'expand', message = list(id = "my_card"))
  })
}

shinyApp(ui, server)