title: How to upload/import a file in the new R shiny version 0.12 using DT package
body: <p>I have just updated shiny to version 0.12 and started to use the DT package (finding it a bit difficult to use but have to do it anyway). Basically I am trying to upload or import a file. This is my server code:</p>
  
  <pre><code> shinyServer(function(input, output, session) {
  
      datasetInput &lt;- reactive({
        infile &lt;- input$FileInput
        if(is.null(infile))
          return(NULL)
        read.table(infile$datapath,header=input$header,sep=input$sep,check.names=F)
      })
  
      output$table = DT::renderDataTable(datasetInput(), server = TRUE)
      })
  
      # Also tried the following code but get the same error &amp; warning:
      # output$table &lt;- DT::renderDataTable({
      #    DT::datatable(datasetInput())
      # },server=TRUE)
  </code></pre>
  
  <p>This is the error I am getting:</p>
  
  <pre><code>Error in datatable(instance, ...) : 
    'data' must be either a matrix or a data frame
  </code></pre>
  
  <p>and the following warning, despite using <code>server = TRUE</code>:</p>
  
  <pre><code>Warning in run(timeoutMs) :
    It seems your data is too big for client-side DataTables. You may consider server-side processing: http://rstudio.github.io/DT/server.html 
  </code></pre>
  
  <p>I know this is very basic, I couldn't find any example that uses the DT package to import data from a file. More questions will pop up for sure, because I am just starting to move everything from 0.11 to 0.12. </p>