Let user download preexisting file in Shiny

[EricLi0480]

Hi!

Here is what the folder for my app looks like:

app.R
server.R
ui.R
www/ (this is a folder)

Inside the www/ folder is a txt file, testfile.txt.

In ui.R, I have the following code:

downloadButton("unit01file01", label = "Example Programs")

In server.R:

server <- function(input, output, session) {
  # Download unit 1 files
  output$unit01file01 <- downloadHandler( # Example programs
    filename = "mytestfile.txt",
    content = function(file) {
      file.copy(file.path(getwd(),'www','testfile.txt'), file)
    },
    contentType = "text/plain"
  )
}

However, the download is giving me an html file (presumably of the app), instead of the desired file we want to download, testfile.txt. What am I doing wrong here?

Thanks!

[prubin]

Your code works for me, both running it on my PC (from RStudio) and running it from shinyapps.io. Does the error occur when running it locally (from RStudio or from a terminal), or when running it from a server? If running from a server, did you install the www folder and the text file on the server?

[EricLi0480]

I'm running it from RStudio. Here's the full code:

app.R:

################################################################################
rm(list = ls())
library(shiny)
library(shinyFiles)
library(bslib)
library(thematic)
library(shinydashboard)

source("ui.R")
source("server.R")

set.seed(500)

shinyApp(ui = ui, server = server) # Run app

ui.R:

rm(list = ls())
library(shiny)
library(shinyFiles)
library(bslib)
library(thematic)
library(shinydashboard)
set.seed(500)

ui <- dashboardPage(
  skin = "black",
  dashboardHeader(
    title = "The Basics of TI-BASIC",
    titleWidth = 250
  ),
  dashboardSidebar(
    width = 250,
    sidebarMenu(
      menuItem("Unit 01: Introduction", tabName = "unit00"),
      menuItem("Unit 01: Input and Output", tabName = "unit01")
    )
  ),
  dashboardBody(
    tabItems(
      tabItem(
        tabName = "unit00",
        fluidRow(
          # Embed video
          box(
            title = "Watch the Lesson",
            tags$iframe(src=(youtube link), 
                        frameborder="0", 
                        allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture")
          ),
          # Files for student
          box(
            title = "No files to download!"
          )
        )
      ),
      tabItem(
        tabName = "unit01",
        fluidRow(
          # Embed video
          box(
            title = "Watch the Lesson",
            tags$iframe(src=(there's a youtube link here that works fine), 
                        frameborder="0", 
                        allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture")
          ),
          # Files for student
          box(
            title = "Download Files",
            downloadButton("unit01file01", label = "Example Programs")
          )
        )
      )
    )
  )
)

server.R:

rm(list = ls())
library(shiny)
library(shinyFiles)
library(bslib)
library(thematic)
library(shinydashboard)
set.seed(500)

server <- function(input, output, session) {
  # Download unit 1 files
  output$unit01file01 <- downloadHandler( # Example programs
    filename = "mytestfile.txt",
    content = function(file) {
      file.copy(file.path(getwd(),'www','testfile.txt'), file)
    },
    contentType = "text/plain"
  )
}

[prubin]

Your UI file contains some issues that convince RStudio that the file ends prematurely. In the two tag$iframe commands, I had to surround the src argument with quotes. That should have nothing to do with file download.

I put a folder named "www" in the folder containing the three .R files, and put a text file named testfile.txt in the www folder. With that, the download feature worked fine for me.