Middleware for Compojure+Ring to add self link in REST API response

wrap-self-link.clj

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(defn wrap-self-link
  [handler]
  (fn [{:keys [scheme server-name server-port uri] :as request}]
    (let [link     (str (name scheme) "://" server-name ":" server-port uri)
          response (handler request)]
      (assoc-in response [:body :links :self] link))))

Link may behave differently if using reverse proxy or load balancer.