Clojure Ring Basic, Etcetera...

user.clj

;; Ring handler is just, just plain old function

(defn always-ok-handler [request]
  "OK")


;; Attach one single handler per http-server instance
;; This http-server will always response with "OK" no matter what
;; request it was given.

(aleph.http.server/start-server always-ok-handler {:port 2222})


;; Compojure routes help us mapping request uri, methods to go
;; to where we want to. 

(compojure.core/routes
  (compojure.core/ANY "/index" [] "Hello there")
  (compojure.core/GET "/motd" [] "Be safe, always be safe!"))


;; Above form will return a ring handler, so better we make ref for it.

(def simple-handler
  (compojure.core/routes
    (compojure.core/ANY "/index" [] "Hello there")
    (compojure.core/GET "/motd" [] "Be safe, always be safe!")))


;; Yes, handler is just plain old function! Here you can check it its
;; do the job by just evaling it. 

(simple-handler {:uri "/index"})  ;;=> {:status 200, :headers {"Content-Type" "text/html; charset=utf-8"}, :body "Hello there"}
(simple-handler {:uri "/motd"})   ;;=> nil
(simple-handler {:uri "/motd" :request-method :get})  ;;=> { ... :body "Be safe, always be safe!"}


;; Middleware testing
(let [req {:uri "/index.php"
           :query-string "q=10"}]
  ((ring.middleware.params/wrap-params identity) req)) ;;=> {:uri ... :query-params {"q" 10} :params {"q" 10}}