Shiny, two action buttons, it only responds to the second button and not to the first button

Question

Tell me in R Shiny, there are two action buttons. I want to update the data according to the button I press. But for some reason it only responds to the second button and not to the first button. What is the solution?

if (interactive()) {
  ui <- fluidPage(
    sidebarLayout(
      sidebarPanel(
        actionButton("action_1", "Get 1"),
        actionButton("action_2", "Get 2"),
      ),
      mainPanel(
        textOutput("result")
      ),
    )
  )
  
  server <- function(input, output) {
    data <- eventReactive(input$action_1, 1)
    data <- eventReactive(input$action_2, 2)
    output$result <- renderText(data())
  }
  
  shinyApp(ui, server)
}

score 5 · Answer 1 · answered Jul 08 '20 at 06:41

The second line of this piece of code overwrites the first one:

data <- eventReactive(input$action_1, 1)
data <- eventReactive(input$action_2, 2)

You can do:

  ui <- fluidPage(
    sidebarLayout(
      sidebarPanel(
        actionButton("action_1", "Get 1"),
        actionButton("action_2", "Get 2"),
      ),
      mainPanel(
        textOutput("result")
      ),
    )
  )
  
  server <- function(input, output) {
    result <- reactiveVal()
    observeEvent(input$action_1, { result(1) })
    observeEvent(input$action_2, { result(2) })
    output$result <- renderText(result())
  }
  
  shinyApp(ui, server)
}

score 0 · Answer 2 · answered Jul 08 '20 at 08:48

If you have many buttons you can simply add a class to it and some simple JS to monitor the last click like so:

library(shiny)

monitorJS <- "$(document).on('click', '.monitor', function () {
                                Shiny.onInputChange('last_click',this.id);
                               });"


ui <- fluidPage(
    tags$head(tags$script(monitorJS)),
    sidebarLayout(
        sidebarPanel(
         uiOutput("buttons")
        ),
        mainPanel(
            textOutput("result")
        ),
    )
)

server <- function(input, output, session) {
    
    output$buttons <- renderUI({
        a <- list()
        for(i in 1:200){
            id <- paste0("action_",i)
            name <- paste0("Get ",i)
            a[[i]] <- actionButton(id, name, class = "monitor")
        }
        tagList(a)
    })
    
    data <- eventReactive(input$last_click,{
        # Your click ligic here
        value <- gsub("action_","",input$last_click)
        value
    })
    
    output$result <- renderText({
        data()
    })

}

shinyApp(ui, server)

Shiny, two action buttons, it only responds to the second button and not to the first button

2 Answers2