R Shiny SweetAlert - Display alert depending on user input

Question

I would like to send a SweetAlert to the app user depending on correct password input and file upload.

My app asks a user to upload a password protected Excel file using the fileInput widget and accepts a password using the passwordInput widget:

  # file select
  output$file_select <- renderUI({
    fileInput("file_select","Import File:",buttonLabel = "Select",
              multiple = FALSE, accept = ".xlsx",placeholder = "No file selected")
  })
  # password input
  output$pword_input <-renderUI({
    passwordInput("pword_input","Password:", "", placeholder = "Enter Excel password")
  })

Reading of the Excel sheet is handled by excel.link and creates a reactive object called raw.data() :

  raw.data <- reactive({
    # Read Excel file
    data_file <- input$file_select
    df <- xl.read.file(data_file$datapath,
                       password =  input$pword_input)
   return(df)
})

Documentation for sendSweetAlert only seems to provide examples for sending an alert on action button press. However, I would like the observeEvent to look for correct password input.

I cannot store the password within the app and so I have currently set the observeEvent that triggers the SweetAlert to look for the creation of the reactive object raw.data() as an indicator that the correct password has been input:

  observeEvent(raw.data(), {
    sendSweetAlert(
      session = session,
      title = "Password Accepted",
      type = "success"
    )
  })

This functions, to a certain extent. If the correct password is input then the SweetAlert is displayed once the reactive object is created as desired. However, input of incorrect password crashes the app.

I hoped someone could help with the correct way to set this up please. I imagine my error is in the use of the observeEvent? However, without storing the password, i'm not sure how else to achieve my aim.

Thanks in advance

Answer 1

xl.read.file throws an error if the password is not correct. So you can try something like that (not tested):

raw.data <- reactive({
    # Read Excel file
    data_file <- input$file_select
    df <- try(xl.read.file(data_file$datapath,
                           password = input$pword_input))
   return(df)
})

observeEvent(raw.data(), {
  if(inherits(raw.data(), "try-error")) {
    sendSweetAlert(
      session = session,
      title = "Wrong password",
      type = "error"
    )
  } else {
    sendSweetAlert(
      session = session,
      title = "Password Accepted",
      type = "success"
    )
  }
})