R/api_utils.R

In hackoregon/rcivicapi: Civic Platform R Utilities

#' @title GET from Civic API
#' @name get_civic_api
#' @description GETs data from a Civic API endpoint
#' @importFrom httr GET
#' @importFrom httr status_code
#' @importFrom httr content
#' @importFrom jsonlite fromJSON
#' @export get_civic_api
#' @param url the URL to GET
#' @param verbose print status info
#' @return a list of two items
#' \itemize{
#'   \item `status_code` integer: the HTTP status code (200 for success)
#'   \item `response`: if `status_code` == 200, the JSON object from the API;
#'     otherwise, the raw text response.
#' }
#' @examples
#' \dontrun{
#' url_base <- "http://service.civicpdx.org/transportation2019/v1/toad"
#' endpoint <- "busPassengerStops"
#' query <- "?limit=10000&lines=10,14&stops=3637,3641,3633&time_range=9,10&service_key=W"
#' url <- paste(url_base, endpoint, query, sep = "/")
#' print(url)
#' response <- rcivicapi::get_civic_api(url, verbose = TRUE)
#' if (response[["status_code"]] == 200) {
#'   View(response[["data"]][["results"]][["features"]])
#' } else {
#'   print(response)
#' }
#' }

get_civic_api <- function(url, verbose) {

  # you shouldn't have to change these!
  tries <- 5
  sleep_seconds <- 10

  # only some response codes should be retried
  retry_allowed <- c()

  for (ixtry in 1:tries) {
    if (verbose) print(url)
    response <- httr::GET(url)
    status_code <- httr::status_code(response)

    # was the GET successful?
    if (status_code == 200) {
      return(list(
        status_code = status_code,
        data = jsonlite::fromJSON(
          httr::content(response, as = "text", encoding = "UTF-8"),
          flatten = TRUE
        )
      ))
    }

    # is it a fatal code?
    if (!(status_code %in% retry_allowed)) {
      return(list(
        status_code = status_code,
        data = httr::content(
          response, as = "text", encoding = "UTF-8"
        )
      ))
    }

    # GET failed but we can retry - sleep and continue retry loop
    if (verbose) {
      print(paste(
        status_code, "sleeping", sleep_seconds
      ))
    }
    Sys.sleep(sleep_seconds)
  }

  # no retry succeeded - return the raw stuff
  return(list(
    status_code = status_code,
    data = httr::content(
      response, as = "text", encoding = "UTF-8")
  ))
}

utils::globalVariables(c(
))