R/util.R

In davidski/emoncmsr: EmonCMS API Interace Library

#' Send a request to emonCMS
#'
#' @return An httr response object content user_agent http_error
#' @importFrom httr GET POST
#' @param uri Leaf node of API endpoint. Appended to `emoncms_uri()`.
#' @param params Any additional query parameters to send. Defaults to NULL.
#' @param method Wether to GET (default) or POST the call.
#' @param post_body For POST calls, any fields to specify in the POST body.
#' @param verbose If set (boolean), will warn on the query parameters to be sent
#' @export
send_emon_request <- function(uri, params = NULL, method = "GET",
                              post_body = NULL, verbose = FALSE) {
  url <- paste0(emoncms_uri(), uri)
  ua <- httr::user_agent("http://github.com/davidski/emoncmsr")

  # currently add the API key to the query string as header support is
  # broken on emoncms.org and only available on emoncms master as of 6/27/17
  query_params <- list(apikey = emoncms_api_key())
  query_params <- c(query_params, params)

  if (verbose)
    warning("Sending query params", (params))

  # send either a POST or GET request, per passed parameters
  if (method != "POST") {
    response <- httr::GET(url, query = query_params, ua,
                        httr::add_headers(Authorization =
                                             paste("Bearer", emoncms_api_key())))
  } else {
    response <- httr::POST(url, query = query_params, body = post_body, ua,
                          httr::add_headers(Authorization =
                                               paste("Bearer", emoncms_api_key())))
  }

  # throw an error if we get an HTTP error back from the API
  if (httr::http_error(response)) {
    stop("Error from emoncms API.")
  }

  response <- httr::content(response, as = "text", encoding = "UTF-8")
  if (response == "ok") { TRUE } else {response}
}

#' Fetch URI to the emoncms server
#'
#' @return The URI to the emonCMS endpoint.
#' @export
emoncms_uri <- function() {
  uri <- Sys.getenv("EMONCMS_URI")

  if (identical(uri, "")) {
    stop("Please set env var EMONCMS_URI to the base of your emoncms API endpoint",
         call. = FALSE)
  }

  uri
}

#' Fetch the emonCMS API key from the environment.
#'
#' @return The API key to use for the emonCMS server.
#' @export
emoncms_api_key <- function() {
  api_key <- Sys.getenv("EMONCMS_API_KEY")

  if (identical(api_key, "")) {
    stop("Please set env var EMONCMS_API_KEY to your emoncms API token",
         call. = FALSE)
  }

  api_key

}