fileInput Upload and update DT:datatable with reactive

[tanthiamhuat]

After user has uploaded the TDMS file, I need to display its Signals in a Datatable, reactively...meaning when new TDMS file is being uploaded, that Signals in the Datatable is updated accordingly.

df_TDMS_upload <- reactive({
  inFile <- input$upload
  if (is.null(input$inFile))
    return(NULL)
  f <- file(paste0('/srv/shiny-server/data/',input$upload[1]), 'rb')
  main <- TdmsFile$new(f)
  main$read_data(f, 0, 4000, sample_rate = 1)
  mainObjectList <- as.list(main$objects)
  close(f)
  Signals <- as.data.frame(names(mainObjectList))
  return(Signals)
})
output$Signal_table <- DT::renderDataTable({
                                           Signals <- df_TDMS_upload()
                                           DT::datatable(Signals)
})

I am surprised why this does not work, it seems simple, and where is exactly the issue that it does not work?
I have debugged line by line, and when put in that filename for the tdms file, that Signals dataframe is available.

[tanthiamhuat]

I am just puzzled why it does not work also when I try with CSV file, which is more straightforward:

df_CSV_upload <- reactive({
  inFile <- input$upload
  if (is.null(input$inFile))
    return(NULL)
  df <- read.csv('/srv/shiny-server/data/test.csv',header=TRUE, sep=',')
  return(df)
})

output$Signal_table <- DT::renderDataTable({
                                           df <- df_CSV_upload()
                                           #df <- read.csv('/srv/shiny-server/data/test.csv',header=TRUE, sep=',')
                                           DT::datatable(df)
})

And when I read directly from CSV file, then it is able to show the table contents. So where is the mistake for the reactive?

[nirgrahamuk]

@tanthiamhuat

Signals <- as.data.frame(names(mainObjectList))
  return(Signals)

You throw away all information and keep only the names ?