idea to keep status on if data are ready in shiny

file_update_reactive.R

library(shiny)

shinyApp(
  
  ui = wellPanel(
    actionButton(
      "file", 
      label = "file upload"
    ),  
    actionButton(
      "update",
      label = "update"
    )
  ),
  
  
  
  server = function(input, output, session){
    observe(print(paste0("file : ", input$file[[1]])))
    observe(print(paste0("update : ", input$update[[1]])))
    observe(print(paste0("file_at_last_update : ", rct_file_at_last_update())))
    observe(print(paste0("is_ready : ", rct_is_ready())))
    
    rct_file_at_last_update <- reactive({
      input$update 
      
      isolate(input$file)

    })
    
    rct_is_ready <- reactive({
      
      is_ready <- 
        input$file > 0 &
        input$file == rct_file_at_last_update()
      
      is_ready
    })
    
  }
  
)