r - 'Reset inputs' button in shiny app

Question

I would like to implement a 'Reset inputs' button in my shiny app.

Here is an example with just two inputs where I'm using the update functions to set the values back to the default values:

library(shiny)

runApp(list(

  ui = pageWithSidebar(

    headerPanel("'Reset inputs' button example"),

    sidebarPanel(
      numericInput("mynumber", "Enter a number", 20),
      textInput("mytext", "Enter a text", "test"),
      tags$hr(),
      actionButton("reset_input", "Reset inputs")
    ),

    mainPanel(
      h4("Summary"),
      verbatimTextOutput("summary")
    )

  ),

  server = function(input, output, session) {

    output$summary <- renderText({
      return(paste(input$mytext, input$mynumber))
    })

    observe({
      input$reset_input
      updateNumericInput(session, "mynumber", value = 20)
      updateTextInput(session, "mytext", value = "test")
    })
  }

))

What I would like to know is if there is also a function that sets back everything to default? That would be useful in case of multiple inputs.

Additionally, I'm not sure if my use of the observe function in order to detect when the action button was hit is the 'proper way' of handling the action buttons?

Answer 1

There isn't such a function in shiny, however, here's a way to accomplish this without having to essentially define your inputs twice. The trick is to use uiOutput and wrap the inputs you want to reset in a div whose id changes to something new each time the reset button is pressed.

library(shiny)

runApp(list(

  ui = pageWithSidebar(

    headerPanel("'Reset inputs' button example"),

    sidebarPanel(
      uiOutput('resetable_input'),
      tags$hr(),
      actionButton("reset_input", "Reset inputs")
    ),

    mainPanel(
      h4("Summary"),
      verbatimTextOutput("summary")
    )

  ),

  server = function(input, output, session) {

    output$summary <- renderText({
      return(paste(input$mytext, input$mynumber))
    })

    output$resetable_input <- renderUI({
        times <- input$reset_input
        div(id=letters[(times %% length(letters)) + 1],
            numericInput("mynumber", "Enter a number", 20),
            textInput("mytext", "Enter a text", "test"))
    })

  }
))