Where is the local host directory of a shiny app in R to display local pdf file?

Question

I am Looking at this Question: displaying a pdf from a local drive in shiny and want to Display a local pdf file.

I placed my pdf within C:\Users\user1\Documents\shiny_pdf\www. The app is placed in C:\Users\user1\Documents\shiny_pdf and i set my working Directory to the latter Directory.

Now i am unsure on how to reference that file within the app.

The author of the answer post in the linked Question states:

so you have to save them in your www directory (a local web server) and access to files with their http(s): URLs (the URL will be something like http://localhost/.../mypdf.pdf)

So i am unsure on how to navigate from http://localhost/ to C:\Users\user1\Documents\shiny_pdf\www.

What i tried:

• I would have assumed i have www is the Server Directory so i would use http://localhost/R-intro.pdf.

• I added an Image to my shiny app and checked its server address in the browser. Then i located the pdf file accordingly. I can open it via: http://127.0.0.1:6023/r-intro.pdf (with 6023 being my port number). But i cant use that either to reference it in the iframe.

• I also tried list.files(), but that would (obv.) give me the files from the working Directory.

• http://localhost/R-intro.pdf also does not work.

The error:

Fehler: Verbindung fehlgeschlagen Firefox kann keine Verbindung zu dem Server unter localhost aufbauen.

which loosely translates to. Connection failed. Firefox can´t make a Connection to the Server under localhost.

Reproducible Code:

1. Save the following file (see below) as, e.g. app.R.

2. Run the following Code to create a WWW directoy for shiny and place a sample pdf into it.

dir.create("www") pdf(file = "www/r-intro.pdf") plot(1) dev.off() list.files()

Here the Code to save in e.g. app.R.

Code:

library(shiny)

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

  observe({
    print(list.files("http://localhost/R-intro.pdf"))
  })

  output$pdfviewer <- renderText({
    return(paste('<iframe style="height:600px; width:100%" src="', input$pdfurl, '"></iframe>', sep = ""))
  })

})


row <- function(...) {
  tags$div(class="row", ...)
}

col <- function(width, ...) {
  tags$div(class=paste0("span", width), ...)
}

ui <- shinyUI(bootstrapPage(

  headerPanel("PDF VIEWER"),

  mainPanel(

    tags$div(
      class = "container",

      row(
        col(3, textInput("pdfurl", "PDF URL"))
      ),
      row(
        col(6, htmlOutput('pdfviewer')),
        col(6, tags$iframe(style="height:600px; width:100%", src="https://localhost/www/R-intro.pdf"))
      )
    )
  )
))


shinyApp(ui, server)

Answer 1

Hmm ok, against advice from the post

col(6, tags$iframe(style="height:600px; width:100%", src="R-intro.pdf")),

just referencing the file seems to work.