R function to download all non-folder files in a google drive folder

download_all_files_in_folder.R

#' Download all the files in a google drive folder.
#'
#' \code{dribble_data} should be obtained using \code{\link[googledrive]{drive_ls}}.
#'
#' @param dribble_data Data frame of class \code{dribble}.
#' @param folder Path to local folder to download data.
#' @param pattern Optional grep pattern; only file names matching this pattern
#' will be included.
#' @param negate Logical; should only file names that don't match the pattern
#' be included instead?
#' @param overwrite Logical; should existing files be overwritten?
#'
#' @return Data frame of class dribble including the files that were downloaded
#'
#' @examples
#' \dontrun{
#' library(tidyverse)
#' library(googledrive)
#' # Make a temporary drive folder
#' folder <- drive_mkdir("temp")
#' # Upload example data
#' files <- map(c(drive_example("chicken.csv"), drive_example("chicken.txt")),
#'             drive_upload, path = folder)
#' # Download all files in the folder
#' folder_contents <- drive_ls("temp")
#' download_all_files_in_folder(folder_contents, tempdir(), overwrite = TRUE)
#' }

download_all_files_in_folder <- function (dribble_data, folder, pattern = NULL,
                                         negate = FALSE, overwrite = FALSE) {

  # Error-checking
  assertthat::assert_that(assertthat::is.dir(folder))
  assertthat::assert_that(is.logical(negate))
  assertthat::assert_that(any(grepl("dribble", class(dribble_data))),
                          msg = "dribble must of class dribble")

  # Filter out folders
  dribble_data <- dplyr::mutate(
    dribble_data,
    mimeType = purrr::map_chr(drive_resource, "mimeType")
  )

  dribble_data <- dplyr::filter(
    dribble_data,
    mimeType != "application/vnd.google-apps.folder"
  )

  # Filter files to download based on pattern
  if(!is.null(pattern)) assertthat::assert_that(assertthat::is.string(pattern))

  if (!is.null(pattern) & !isTRUE(negate)) {
    dribble_data <- dplyr::filter(
      dribble_data,
      grepl(pattern, dribble_data$name)
    )
  }

  if (!is.null(pattern) & isTRUE(negate)) {
    dribble_data <- dplyr::filter(
      dribble_data,
      !grepl(pattern, dribble_data$name)
    )
  }

  assertthat::assert_that(nrow(dribble_data) > 0,
                          msg = "No data to download under these arguments")

  # Download non-folders and anything passing filter
  purrr::walk2(
    purrr::map(dribble_data$id, googledrive::as_id),
    fs::path(folder, dribble_data$name),
    googledrive::drive_download,
    overwrite = overwrite
  )

  # Return the filtered data that was downloaded
  dribble_data
}