related_items()

[JosiahParry]

Is your feature request related to a problem? Please describe.

This adds a feature to identify related items for a given item ID

Describe the solution you'd like

This is a draft! It does not handle pagination which should be handled!!!

#' Find Related Items
#'
#' @param x an object created with [`arc_open()`]
#' @param direction default `"reverse"`. One of `"reverse"` or `"forward"` defining the direction of the relationship.
#' @inheritParams add_item
#' @references [`/relatedItems` API Doc](https://developers.arcgis.com/rest/users-groups-and-items/related-items.htm)
related_items <- function(
    x,
    direction = c("reverse", "forward"),
    sort_order = c("asc", "desc"),
    host = arc_host(),
    token = Sys.getenv("ARCGIS_TOKEN")
) {

  # validate args
  .dir <- rlang::arg_match(direction)
  sort_order <- rlang::arg_match(sort_order)

  item_id <- x[["serviceItemId"]]

  # https://[root]/content/items/[itemID]/relatedItems
  req <- httr2::req_url_path_append(
    httr2::request(host),
    "sharing/rest/content/items",
    item_id,
    "relatedItems"
  )

  req_body <- httr2::req_body_form(
    req,
    direction = .dir,
    sordOrder = sort_order,
    token = token,
    f = "json"
  )

  # perform request
  resp <- httr2::req_perform(req_body)

  # parse body
  RcppSimdJson::fparse(
    httr2::resp_body_string(resp)
  )
}

Additional context

Need to migrate to httr2 v.1.0 first for pagination helpers.