How to use renderDataTable in Shinny R's file upload example

Question

I am trying to create my first Shiny R application, which does two things:

1. Display user uploaded CSV file
2. Count user selected rows

To achieve these features, I need to combine two examples file upload and row selection, which involves switching renderTable to renderDataTable. However, I am only able to display the data using renderDataTable, but not be able to pass arguments like callback and options into it.

Here is the server.R code

shinyServer(function(input, output) {
  output$contents <- renderDataTable({
    inFile <- input$file1
    if (is.null(inFile))
        return(NULL)
    subset(read.csv(inFile$datapath, header=input$header, sep=input$sep, quote=input$quote), select=input$show_vars)
  })
})

If I change the above function this case (below), I got the following errors server.R:9:5: unexpected 'if'. I think this is related to building a reactive file upload application, which I could not find good examples... Can anyone give me some suggestions? Thanks!

shinyServer(function(input, output) {
  output$contents <- renderDataTable(
    inFile <- input$file1
    if (is.null(inFile))
      return(NULL)
   subset(read.csv(inFile$datapath, header=input$header, sep=input$sep, quote=input$quote), select=input$show_vars),
   options = list(pageLength = 10),
   callback = "function(table) {
         table.on('click.dt', 'tr', function() {
           $(this).toggleClass('selected');
           Shiny.onInputChange('rows',
                               table.rows('.selected').indexes().toArray());
         });
       }"
  )
})

Answer 1

The first argument to renderDataTable should be an expression. You need to wrap your code in curly braces to pass this first section of code as an expression:

shinyServer(function(input, output) {
  output$contents <- renderDataTable({
    inFile <- input$file1
    if (is.null(inFile))
      return(NULL)
    subset(read.csv(inFile$datapath, header=input$header, sep=input$sep, quote=input$quote), select=input$show_vars)
  }
  , options = list(pageLength = 10),
  , callback = "function(table) {
         table.on('click.dt', 'tr', function() {
           $(this).toggleClass('selected');
           Shiny.onInputChange('rows',
                               table.rows('.selected').indexes().toArray());
         });
       }"
  )
})