trailing-slash-middleware

(defn ignore-trailing-slash
  "Modifies the request uri before calling the handler.
  Removes a single trailing slash from the end of the uri if present.

  Useful for handling optional trailing slashes until Compojure's route matching syntax supports regex.
  Adapted from http://stackoverflow.com/questions/8380468/compojure-regex-for-matching-a-trailing-slash"
  [handler]
  (fn [{uri :uri :as request}]
    (handler (assoc request :uri (cond (= "/" uri) uri
                                       (.endsWith uri "/") (apply str (butlast uri))
                                       :else uri)))))