R shiny : How to capture change in a specific directory?

July 26, 2022

I have a shinyApp, where I would like to capture the change in a specific directory.

i.e : the user click on the shinyDirButton, creates a sub-directory in a specific directory. I would like to capture any change in this directory (creation, deletion). I tried to use reactiveValues but I didn’t succeed

    library(shiny)

ui = fluidPage(sidebarLayout(
  sidebarPanel(
    class = "sidebar_upload",
    id = "form",
    
    
    tags$h1("1- Choose a folder"),
    shinyFiles::shinyDirButton(
      id = 'choose_directory',
      label = 'Choose a folder',
      title = 'Choose a folder',
      multiple = F
    ),
    br(),
    br(),
    br(),
    actionButton("button", "Update")
    
  ),
  
  mainPanel(uiOutput(outputId = "test"))
))



server <- function(input, output, session) {
  r_global <- reactiveValues()
  
  observe({
    r_global$volumes = c(home = 'C:/')
    r_global$dossier = list.dirs(r_global$volumes,
                                 recursive = F,
                                 full.names = F)
    
    
    
    shinyFiles::shinyDirChoose(
      input = input,
      id = 'choose_directory',
      roots = r_global$volumes,
      session = session
    )
  })
  
  observeEvent(input$button, {
    print(r_global$dossier)
  })
}

shinyApp(ui, server)

>Solution :

You have to replace your first observe by an observeEvent:

   library(shiny)

ui = fluidPage(sidebarLayout(
  sidebarPanel(
    class = "sidebar_upload",
    id = "form",
    
    
    tags$h1("1- Choose a folder"),
    shinyFiles::shinyDirButton(
      id = 'choose_directory',
      label = 'Choose a folder',
      title = 'Choose a folder',
      multiple = F
    ),
    br(),
    br(),
    br(),
    actionButton("button", "Update")
    
  ),
  
  mainPanel(uiOutput(outputId = "test"))
))



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

#############################  
### here add observeEvent ###
#############################
  observeEvent(input$button, {
    r_global$volumes = c(home = '~/project/SHINY/wedding/PROJET/')
    r_global$dossier = list.dirs(r_global$volumes,
                                 recursive = F,
                                 full.names = F)
    
    
    
    shinyFiles::shinyDirChoose(
      input = input,
      id = 'choose_directory',
      roots = r_global$volumes,
      session = session
    )
  })
  
  observeEvent(input$button, {
    print(r_global$dossier)
  })
}

shinyApp(ui, server)