interceptors.clj

(ns myapi.interceptors)

(def user-auth
  {:before (fn [context]
             (update-in context :password h/encrypt-password))
   :after (fn [context]
            (dissoc context [:password]))})

(def interceptors [user-auth])

routes.clj

(ns myapi.routes)

(def routes
  (start-server ...
    (mount ::myapi.my-service ::myapi.interceptors)))

services.clj

(ns myapi.services)

(defn fetch [id params]
  (db/select-one id params))

(defn fetch* [params]
  (db/select params))

(defn create! [data params]
  (db/insert! data params))

Using services with full interceptors:

(with-hooks [::myapi.interceptors]
  (create! {:username "Fulano" :password "segredo"}))