downloadFile: downloadFile module server function

Description

Server-side function for the downloadFileButton. This is a custom high-functionality button for file downloads supporting single or multiple download types. The server function is used to provide the data for download.

Usage

downloadFile(
  id,
  logger = NULL,
  filenameroot = "download",
  datafxns = NULL,
  aspectratio = 1
)

Value

no return value, called for downloading selected file type

Arguments

id: ID of the Module's UI element
logger: logger to use
filenameroot: the base text used for user-downloaded file - can be either a character string or a reactive expression that returns a character string
datafxns: a named list of functions providing the data as return values. The names for the list should be the same names that were used when the button UI was created.
aspectratio: the downloaded chart image width:height ratio (ex: 1 = square, 1.3 = 4:3, 0.5 = 1:2). Where not applicable for a download type it is ignored (e.g. data downloads).

Shiny Usage

This function is not called directly by consumers - it is accessed in server.R using the same id provided in downloadFileButton:

downloadFile(id, logger, filenameroot, datafxns)

Examples

Run this code

if (interactive()) {
   library(shiny)
   library(periscope2)
   shinyApp(ui = fluidPage(fluidRow(column(width = 6,
     # single download type
     downloadFileButton("object_id1",
                        downloadtypes = c("csv"),
                        hovertext     = "Button 1 Tooltip")),
      column(width = 6,
      # multiple download types
      downloadFileButton("object_id2",
                         downloadtypes = c("csv", "tsv"),
                         hovertext     = "Button 2 Tooltip")))),
     server = function(input, output) {
       # single download type
       downloadFile(id           = "object_id1",
                    logger       = "",
                    filenameroot = "mydownload1",
                    datafxns     = list(csv = reactiveVal(iris)),
                    aspectratio  = 1)
       # multiple download types
       downloadFile(id           = "object_id2",
                    logger       = "",
                    filenameroot = "mydownload2",
                    datafxns     = list(csv = reactiveVal(mtcars),
                    tsv = reactiveVal(mtcars)))
   })
}