Nested function to retrieve data from multiple URLs (with authentication) in R

Question

My code below is designed to retrieve data (and its metadata) with authentication through an API endpoint, and return all metadata into a dataframe. I want to create a nested function to repeat this same process for another API endpoint with the same authentication and append the result from the second endpoint to the first, into a single dataframe (they both have the same data structure and headers). I don't know where in this process should I put link_to_endpoint2, and how to do the nesting, and append the results, etc.

get_data <- function(uid, credentials, root_url) {

  cookie <- credentials$cookie
  token <- credentials$token

  start_time <- Sys.time()
  print (start_time)
  url <- paste0(root_url, 'link_to_endpoint1', uid)
  resp <- httr::GET(url,
                    httr::add_headers(.headers = c(`Content-Type` = "application/json", 
                                                   Cookie = cookie, `X-CSRF-Token` = token)),
                    body = body, 
                    encode = "json")

  httr::warn_for_status(resp)
  resources <- httr::content(resp)
  access_check <- resources$result$error
  assertthat::assert_that(is.null(access_check),
                          msg = 'Access denied')

  resources <- resources$result[[1]]$resources
  res_ids <- purrr::map_chr(resources, 'id')
  res_urls <- purrr::map_chr(resources, 'url')
  res_desc <- purrr::map_chr(resources, 'description')
  res_format <- purrr::map_chr(resources, 'format')
  res_rclass <- purrr::map_chr(resources, 'data_classification_of_file')
  res_rtype <- purrr::map_chr(resources, 'mimetype')
  res_rname <- purrr::map_chr(resources, 'name')
  out <- data.frame(res_ids,
                    res_urls,
                    res_desc,
                    res_format,
                    res_rclass,
                    res_rtype,
                    res_rname,
                    stringsAsFactors = FALSE)
  out$id <- uid
  end_time <- Sys.time()
  print (end_time)
  process_time <- (end_time - start_time)
  print(process_time)
  return(out)
}

Answer 1

You'll have to test this solution but you can try

Changing these lines to

# Old line
New line

# get_data <- function(uid, credentials, root_url) {
get_data <- function(uid, credentials, root_url, link) {

# url <- paste0(root_url, 'link_to_endpoint1', uid)
url <- paste0(root_url, link, uid)

Then you could call this function with (assuming you have already loaded purrr)

links <- c('link_to_endpoint1', 'link_to_endpoint2')
desired <- map_df(links, ~get_data(uid, credentials, root_url, .x))