R Shiny: Update a R6 Object on different actionButtons

Question

I am trying to build a shiny update that allows the user to update a R6 Class object by clicking different actionButtons, as shown in the example below.

I also looked into different options such as using reactiveValues etc, but I cannot get it to work properly.

library(shiny)
library(R6)

DataInfo <- R6Class(
  classname = "DataInfo",
  public = list(
    data1 = NULL,
    data2 = NULL,
    initialize = function() {},
    AddData1 = function(data1 = NA) {
      self$data1 <- data1
    },
    AddData2 = function(data2 = NA) {
        self$data2 <- data2
    }
  )
)

ui <- fluidPage(
  actionButton("add_data1_btn", "Add Data1"),
  actionButton("add_data2_btn", "Add Data2"),
  verbatimTextOutput("output")
)

server <- function(input, output, session) {
  my_info <- DataInfo$new()
  
  observeEvent(input$add_data1_btn, {
    my_info$AddData1(data1 = "Sample data1")
  })
  
  observeEvent(input$add_data2_btn, {
    my_info$AddData2("Sample data2")
  })
  
  output$output <- renderPrint({
    list(
      data1 = my_info$data1,
      data2 = my_info$data2

    )
  })
}

shinyApp(ui, server)

How can I get my app to react to changes in my_data?

Limey · Accepted Answer · 2023-07-07T10:15:42.483

Initially, I thought wrapping my_info in a reactiveValues would work, but it didn't.

An easy solution is simply to add references to the two buttons in your renderPrint.

[By the way, if you put a print(my_info) in each of your button observers, you'll see that my_info does update, but the app doesn't realise that it has. So the answer to your question "Is there a way how I can make the DataInfo object reactive to the input so it updates its state?" is that "It already does". So what I think you meant to ask is "How can I get my app to react to changes in my_info?". That's a subtle but important difference.]

library(shiny)
library(R6)

DataInfo <- R6Class(
  classname = "DataInfo",
  public = list(
    data1 = NULL,
    data2 = NULL,
    initialize = function() {},
    AddData1 = function(data1 = NA) {
      self$data1 <- data1
    },
    AddData2 = function(data2 = NA) {
      self$data2 <- data2
    }
  )
)

ui <- fluidPage(
  actionButton("add_data1_btn", "Add Data1"),
  actionButton("add_data2_btn", "Add Data2"),
  verbatimTextOutput("output")
)

server <- function(input, output, session) {
  my_info <- DataInfo$new()
  
  observeEvent(input$add_data1_btn, {
    my_info$AddData1(data1 = "Sample data1")
  })
  
  observeEvent(input$add_data2_btn, {
    my_info$AddData2("Sample data2")

  })
  
  output$output <- renderPrint({
    input$add_data1_btn
    input$add_data2_btn
    list(
      data1 = my_info$data1,
      data2 = my_info$data2
    )
  })
}

shinyApp(ui, server)

You are right, I edited my question! – lukp Jul 07 '23 at 10:08 — lukp, Jul 07 '23 at 10:08

R Shiny: Update a R6 Object on different actionButtons

1 Answers1