R/get_playlist_item_ids.R

In tuber: Client for the YouTube API

#' Get Playlist Item IDs
#'
#' @param filter string; Required.
#' named vector of length 1
#' potential names of the entry in the vector:
#' \code{item_id}: comma-separated list of one or more unique playlist item IDs.
#' \code{playlist_id}: YouTube playlist ID.
#'
#' @param part Required. Comma separated string including one or more of the
#' following: \code{contentDetails, id, snippet, status}. Default:
#' \code{contentDetails}.
#' @param max_results Maximum number of items that should be returned.
#' Integer. Optional. Default is 50. Values over 50 will trigger multiple
#' requests and may increase API quota usage.
#' @param simplify returns a data.frame rather than a list.
#' @param page_token specific page in the result set that should be
#' returned, optional
#' @param video_id  Optional. request should return only the playlist
#' items that contain the specified video.
#' @param \dots Additional arguments passed to \code{\link{tuber_GET}}.
#'
#' @return playlist items
#' @export
#' @references \url{https://developers.google.com/youtube/v3/docs/playlists/list}
#'
#' @examples
#' \dontrun{
#'
#' # Set API token via yt_oauth() first
#'
#' get_playlist_items(filter =
#'                        c(playlist_id = "PLrEnWoR732-CN09YykVof2lxdI3MLOZda"))
#' get_playlist_items(filter =
#'                        c(playlist_id = "PL0fOlXVeVW9QMO3GoESky4yDgQfK2SsXN"),
#'                        max_results = 51)
#' }

get_playlist_item_ids <- function(filter = NULL, part = "contentDetails",
                                  max_results = 50, video_id = NULL,
                                  page_token = NULL, simplify = TRUE, ...) {

  # Modern validation using checkmate
  assert_integerish(max_results, len = 1, lower = 1, .var.name = "max_results")
  assert_character(filter, len = 1, .var.name = "filter")
  assert_choice(names(filter), c("item_id", "playlist_id"),
                .var.name = "filter names (must be 'item_id' or 'playlist_id')")
  assert_character(part, len = 1, min.chars = 1, .var.name = "part")
  assert_logical(simplify, len = 1, .var.name = "simplify")

  if (!is.null(video_id)) {
    assert_character(video_id, len = 1, min.chars = 1, .var.name = "video_id")
  }
  if (!is.null(page_token)) {
    assert_character(page_token, len = 1, min.chars = 1, .var.name = "page_token")
  }

  translate_filter <- c(item_id = "id", playlist_id = "playlistId")
  filter_name <- translate_filter[names(filter)]
  names(filter) <- filter_name

  querylist <- list(part = part,
                    maxResults = min(max_results, 50),
                    pageToken = page_token, videoId = video_id)
  querylist <- c(querylist, filter)

  res <- tuber_GET("playlistItems", querylist, ...)
  items <- res$items
  next_token <- res$nextPageToken

  while (length(items) < max_results && !is.null(next_token)) {
    querylist$pageToken <- next_token
    querylist$maxResults <- min(50, max_results - length(items))
    a_res <- tuber_GET("playlistItems", querylist, ...)
    items <- c(items, a_res$items)
    next_token <- a_res$nextPageToken
  }

  item_ids <- sapply(items, function(x) x$id)
  return(item_ids)
}