How to download multiple csv files in a zipped folder in Shiny

[Edward Lee]

Hi - 

Using base package data, I put together a simple downloadHandler code that outputs multiple files into one zipped folder. I seem to get an error that I'm not sure how to correct. Could someone please help me point out where the gap in this code is?

Thanks,

Ed

library(shiny)

# server.R
server <- function(input, output) {

  datasetInput <- reactive({
    return(list(rock=rock, pressure=pressure, cars=cars))
  })

  output$downloadData <- downloadHandler(
    filename = 'pdfs.zip',
    content = function(fname) {
      tmpdir <- tempdir()
      setwd(tempdir())
      print(tempdir())

      fs <- c("rock.csv", "pressure.csv", "cars.csv")
      write.csv(datasetInput()$rock, file = "rock.csv", sep =",")
      write.csv(datasetInput()$pressure, file = "pressure.csv", sep =",")
      write.csv(datasetInput()$cars, file = "cars.csv", sep =",")
      print (fs)

      zip(zipfile=fname, files=fs)
    },
    contentType = "application/zip"
  )

}

# ui.R
ui <- shinyUI(fluidPage(
  titlePanel('Downloading Data'),
  sidebarLayout(
    sidebarPanel(
      downloadButton('downloadData', 'Download')
    ),
    mainPanel()
    )
  )
  )

shinyApp(ui = ui, server = server)

[Joe Cheng]

I'd put a browser() call right after the call to zip(), and look in the temp directory. Possibly you'll find that instead of fname, zip decided to save it to fname + ".zip"? If so, you'll have to rename it to fname. Sorry about that.

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[Edward Lee]

Thank you! 

Just in case anyone else is looking for a solution, I tried "if(file.exists(paste0(fname, ".zip"))) {file.rename(paste0(fname, ".zip"), fname)}" after the zip() call, and it worked like how I wanted. 

Solution referenced from: https://groups.google.com/forum/?utm_medium=email&utm_source=footer#!msg/shiny-discuss/D5F2nqrIhiM/ZshRutFpiVQJ

[Joe Cheng]

That's such a shame. I'll see if I can make this unnecessary (by giving you a value for fname that includes the correct extension)--your "if" there is a good idea, hopefully your code will not need to change.