Capture the label of an actionButton once it is clicked

Question

Is it possible to capture the label of an actionButton once it is clicked?

Imagine I have 3 buttons on my ui.R and depending on which one I click I want to perform a different action on the server.R.

One caveat is that the buttons are created dynamically on the server.R with dynamic labels (thus the necessity of capturing the label on click)

Thanks

Answer 1

Something like that ?

library(shiny)

server <- function(input, session, output) {

  output$printLabel <- renderPrint({input$btnLabel})

}

ui <- fluidPage(

  actionButton("btn1", "Label1", 
               onclick = "Shiny.setInputValue('btnLabel', this.innerText);"),
  actionButton("btn2", "Label2", 
               onclick = "Shiny.setInputValue('btnLabel', this.innerText);"),

  verbatimTextOutput("printLabel")  

)

shinyApp(ui = ui, server = server)

Answer 2

1) What button was clicked last by the user?

To answer this you can user observeEvent function and by setting up a a variable using reactiveValues function. Make sure you update your libraries and work in the latest version of R (version 3.1.3) as shiny is dependant on this version. Working on windows you can follow example on how to update here

rm(list = ls())
library(shiny)

ui =fluidPage(
  sidebarPanel(
    textInput("sample1", "Name1", value = "A"),
    textInput("sample2", "Name2", value = "B"),
    textInput("sample3", "Name3", value = "C"),
    div(style="display:inline-block",uiOutput("my_button1")),
    div(style="display:inline-block",uiOutput("my_button2")),
    div(style="display:inline-block",uiOutput("my_button3"))),
  mainPanel(textOutput("text1"))
)

server = function(input, output, session){

  output$my_button1 <- renderUI({actionButton("action1", label = input$sample1)})
  output$my_button2 <- renderUI({actionButton("action2", label = input$sample2)})
  output$my_button3 <- renderUI({actionButton("action3", label = input$sample3)})

  my_clicks <- reactiveValues(data = NULL)

  observeEvent(input$action1, {
    my_clicks$data <- input$sample1
  })

  observeEvent(input$action2, {
    my_clicks$data <- input$sample2
  })  

  observeEvent(input$action3, {
    my_clicks$data <- input$sample3
  })  

  output$text1 <- renderText({ 
    if (is.null(my_clicks$data)) return()
    my_clicks$data
  })
}
runApp(list(ui = ui, server = server))

2) Save the clicks for further manipulation is below

Here's small example based on the work of jdharrison from Shiny UI: Save the Changes in the Inputs and the shinyStorage package.

rm(list = ls())
#devtools::install_github("johndharrison/shinyStorage")
library(shinyStorage)
library(shiny)

my_clicks <- NULL

ui =fluidPage(
  #
  addSS(),
  sidebarPanel(
    textInput("sample_text", "test", value = "0"),
    uiOutput("my_button")),
  mainPanel(uiOutput("text1"))
)

server = function(input, output, session){
  ss <- shinyStore(session = session)

  output$my_button <- renderUI({
    actionButton("action", label = input$sample_text)
  })

  observe({
    if(!is.null(input$sample_text)){
      if(input$sample_text != ""){
        ss$set("myVar", input$sample_text)
      }
    }
  })  

  output$text1 <- renderUI({
    input$action
    myVar <- ss$get("myVar")
    if(is.null(myVar)){
      textInput("text1", "You button Name")
    }else{
      textInput("text1", "You button Name", myVar)          
    }
  })
}
runApp(list(ui = ui, server = server))