Sessions

Sessions in Ring work a little differently than you might expect, because Ring attempts to be functional when possible.

Session data is passed via the request map on the :session key. The following example prints out the current username from the session.

(use 'ring.middleware.session
     'ring.util.response)

(defn handler [{session :session}]
  (response (str "Hello " (:username session)))

(def app
  (wrap-session handler))

To change the session data, you can add a :session key to the response that contains the updated session data. The next example counts the number of times the current session has accessed the page.

(defn handler [{session :session}]
  (let [count   (:count session 0)
        session (assoc session :count (inc count))]
    (-> (response (str "You accessed this page " count " times."))
        (assoc :session session))))