add a demo for one-legged OAuth1 using Noun Project API

NEWS.md

@@ -1,5 +1,7 @@
 # httr 1.3.1.9000
 
+* New demo about OAuth1 One-legged using Noun Project API (@cderv, #548)
+
 * By default, `RETRY()` now terminates on any successful request, regardless
   of the value of `terminate_on`. To return to the previous behaviour,
   set `terminate_on_success = FALSE` (#522).

demo/00Index

@@ -1,4 +1,5 @@
 connection-sharing  Demonstration of how connection sharing saves time
+oauth1-nounproject  Using noun project api with OAuth 1.0 one-legged
 oauth1-twitter      Using twitter api with OAuth 1.0
 oauth1-vimeo        Using vimeo api with OAuth 1.0
 oauth1-yahoo        Using yahoo api with OAuth 1.0

demo/oauth1-nounproject.r

@@ -0,0 +1,44 @@
+library(httr)
+
+# Noun Project has an API secured with OAuth 1.0a One-legged. A client key and a
+# secret must be used to sign requests when accessing the API. This is an
+# exemple using OAuth 1.0a One legged auth mechanism
+# http://oauthbible.com/#oauth-10a-one-legged
+
+# 1. Register an application to get required keys:
+# https://thenounproject.com/accounts/login/?next=/developers/apps/
+# Add the below  environment variable to your session
+# (helper function : usethis::edit_r_environ())
+nouns_app <- oauth_app("noun_project",
+                       key = Sys.getenv("NOUN_API_KEY"),
+                       secret = Sys.getenv("NOUN_API_SECRET"))
+
+# 2. Each request must be signed using the app key and secret
+#    see ?oauth_signature for more information on signature
+url <- "http://api.thenounproject.com/icon/15"
+signature <- oauth_signature(url, method = "GET", app = nouns_app)
+res <- GET(url, oauth_header(signature))
+stop_for_status(res)
+content(res)
+
+# 3. Create a wrapper function to sign each request more easily
+get_nouns_api <- function(endpoint,
+                          baseurl = "http://api.thenounproject.com/",
+                          app = nouns_app,
+                          ...) {
+  url <- modify_url(baseurl, path = endpoint)
+  info <- oauth_signature(url, app = app)
+  header_oauth <- oauth_header(info)
+  GET(url, header_oauth, ...)
+}
+res <- get_nouns_api("collections")
+stop_for_status(res)
+content(res)
+
+# 4. Signing request requires the METHOD used. If the API has a POST for
+# example, you must take it into account.
+url <- "http://api.thenounproject.com/notify/publish?test=1"
+signature <- oauth_signature(url, method = "POST", app = nouns_app)
+res <- POST(url, oauth_header(signature), body = list(icons = 15), encode = 'json')
+stop_for_status(res)
+content(res)