R shiny - Change text fileInput after upload

shiny
1

I want to change the placeholder in fileInput after a file has been uploaded, i.e. customize the "No file selected" to any string I choose.
NoFileSelected

I found how to customize the progress bar label, so I'm guessing the code should be quite similar. This is what I tried so far:

library(shiny)
library(shinyjs)

jscode_upload_msg <- " Shiny.addCustomMessageHandler('upload_msg', function(msg) {
  var target = $('#fileUpload_progress').children()[0];
  target.innerHTML = msg;
}); "

jscode_upload_txt <- " Shiny.addCustomMessageHandler('upload_txt', function(txt) {
  var target = $('#fileUpload_header').children()[1].children()[0];
  target.innerHTML = txt;
}); "

ui <- fluidPage( 
  useShinyjs(),
  tags$script(jscode_upload_msg),
  tags$script(jscode_upload_txt),
  
  fileInput("fileUpload",  "File to upload") 
)

server <- function(input, output, session ) {
  observe({
    req(input$fileUpload)
    session$sendCustomMessage("upload_msg", "YOUR TEXT")
    session$sendCustomMessage("upload_txt", "SOME OTHER TEXT")
  })
}

shinyApp(ui = ui, server = server)

From r - Shiny customise fileInput - Stack Overflow, it seems that the input field is in the second position. However, I am not sure how to write the jscode. Any advice?

2

you can achieve this effect while avoiding writing javascript.
I make the fileInput have no label,
I control the 'label' by constructing a label explicitly, and tie it to the activity of the fileUpload

library(shiny)
library(shinyjs)

jscode_upload_msg <- " Shiny.addCustomMessageHandler('upload_msg', function(msg) {
  var target = $(\"#fileUpload_progress\").children()[0];
  target.innerHTML = msg;
}); "



ui <- fluidPage( 
  useShinyjs(),
  tags$script(jscode_upload_msg),
  div(
    uiOutput("fileUpload_label"),
  fileInput("fileUpload",  label=NULL) )
  
)

server <- function(input, output, session ) {
  observe({
    req(input$fileUpload)
    session$sendCustomMessage("upload_msg", "YOUR TEXT")
   
  })
 output$fileUpload_label<-renderUI({
   if(isTruthy(input$fileUpload))
     tags$label(paste0("File Input ",sample.int(9999,1)))
   else 
     tags$label("initial label")
 })
 
}

shinyApp(ui = ui, server = server)
3

Thank you very much for your answer. I think my question was not precise enough, I edited it to explain more clearly what I am trying to achieve.

4

The initial placeholder can be adjusted at initialisation

 fileInput("fileUpload",placeholder="my own string")
5

I am basically looking for an updateFileInput that could work as: updateFileInput("fileUpload",placeholder="my own string")

6

having googled this, I found that you already received an answer on stackoverflow.

jscode_upload_txt <- " Shiny.addCustomMessageHandler('upload_txt', function(txt) {
  var target = $('#fileUpload').parent().parent().parent().find('input[type=text]');
  target.val(txt);
}); "
7

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