upload and view a pdf in R shiny

Question

I have a simple shiny app in R for reading a PDF file from the user and display it. I can't seem to get it to work. On the shiny server in the www directory I see a 1 KB file with the name "myreport.pdf" that just has the first character

library(shiny)

ui <- shinyUI(fluidPage(

  titlePanel("Testing File upload"),

  sidebarLayout(
    sidebarPanel(
      fileInput('file_input', 'upload file ( . pdf format only)', accept = c('.pdf'))
    ),

    mainPanel(
      uiOutput("pdfview")
    )
  )
))

server <- shinyServer(function(input, output) {

  observe({
    req(input$file_input)
    test_file <- readBin(input$file_input$datapath, what="character") 
    writeBin(test_file, "www/myreport.pdf")
  })


  output$pdfview <- renderUI({
    tags$iframe(style="height:600px; width:100%", src="myreport.pdf")
  })

})

shinyApp(ui = ui, server = server)

Answer 1

I think the issue is with the binary reading and writing. Instead trying to copy the files using file.copy seems to work. Also I've taken the iframe inside observeEvent for the iframe to update every time the pdf is uploaded in the same session.

Updated Code:

library(shiny)

ui <- shinyUI(fluidPage(

  titlePanel("Testing File upload"),

  sidebarLayout(
    sidebarPanel(
      fileInput('file_input', 'upload file ( . pdf format only)', accept = c('.pdf'))
    ),

    mainPanel(
      uiOutput("pdfview")
    )
  )
))

server <- shinyServer(function(input, output) {

  observe({
    req(input$file_input)

     #test_file <- readBin(input$file_input$datapath, what="raw") 

     #writeBin(test_file, "myreport.pdf")

     #cat(input$file_input$datapath)

     file.copy(input$file_input$datapath,"www", overwrite = T)



  output$pdfview <- renderUI({
    tags$iframe(style="height:600px; width:100%", src="0.pdf")
  })

  })

})

shinyApp(ui = ui, server = server)