Update MultiSlider.shinyInput()

[davide-zinghini]

Hello everyone. I'm using shiny.blueprint package and it is very helpful.

I created on the UI a MultiSlider with 3 handles using the MultiSlider.shinyInput() function. If I need to update the handles value server-side, how can I do this?

For other default Shiny inputs it is easy, I can just use updateSelectInput, updateNumericInput, etc.

Thank you,
Davide

[kamilzyla]

Hi @davide-zinghini and thanks for your interest in shiny.blueprint!

Most .shinyInput() components can be updated with shiny.react::updateReactInput(). However, MultiSlider.shinyInput() was a tricky component and it uses a custom implementation which doesn't support updates.

It's still possible to have a MultiSlider which can be updated on the server, albeit it's not that pretty. You'll need to use the underlying MultiSlider React component directly and keep its value in a reactive. Check out this example:

library(shiny.blueprint)

defaultValue <- c(3, 7)

shinyApp(
  ui = Card(
    reactOutput("slider"),
    Button.shinyInput("reset", "Reset")
  ),
  server = function(input, output) {
    value <- reactiveVal(defaultValue)
    observe(value(input$value)) |> bindEvent(input$value)
    observe(value(defaultValue)) |> bindEvent(input$reset)

    output$slider <- renderReact({
      MultiSlider(
        onChange = setInput("value"),
        MultiSliderHandle(value = value()[1]),
        MultiSliderHandle(value = value()[2])
      )
    })
  }
)

[davide-zinghini]

Hi @kamilzyla , thank you for your reply. I needed something similar to shiny.react::updateReactInput() because I have to initialise and create the MultiSlider UI-side and later, using an observeEvent(), update its values server-side. Even if I don't trigger the actions inside the observeEvent, the MultiSlider have to exist.