Display pop up when user uploads file with the wrong extension in shiny app-CodePudding

In the app below when the user does not upload a .xls file I want a pop up to be displayed. Now it appears only in the beginning but if upload another lets say doc file it is hidden. I do not care it is with shinyalert package or other method.

library(shiny)
library(shinyalert)

ui <- fluidPage(
  useShinyalert(),  # Set up shinyalert
  fileInput('file1', 'Choose xls file',
            accept = c(".xls")
  )
)

server <- function(input, output, session) {
  observeEvent(input$file1, {
    if (is.null(input$file1))
    # Show a modal when the button is pressed
    shinyalert("Oops!", "Something went wrong.", type = "error")
  }, ignoreNULL = FALSE)
}

shinyApp(ui, server)

CodePudding user response：

This also resets the fileInput:

library(shiny)
library(tools)

ui <- fluidPage(
  uiOutput("fileUpload")
)

server <- function(input, output, session) {
  
  showModal(modalDialog("My startup modal..."))
  
  resetFileUpload <- reactiveVal(FALSE)
  output$fileUpload <- renderUI({
    resetFileUpload() # reactive dependency
    resetFileUpload(FALSE)
    fileInput('file1', 'Choose xls file', accept = c(".xls"))
  })
  
  observeEvent(input$file1, {
    if(file_ext(input$file1$name) != "xls"){
      resetFileUpload(TRUE)
      showModal(modalDialog("That's not a .xls file"))
    }
  })
}

shinyApp(ui, server)