re-natal/resources/cljs-reagent/handlers.cljs

(ns $PROJECT_NAME_HYPHENATED$.handlers
  (:require
    [re-frame.core :refer [register-handler after]]
    [schema.core :as s :include-macros true]
    [$PROJECT_NAME_HYPHENATED$.db :refer [app-db schema]]))

;; -- Middleware ------------------------------------------------------------
;;
;; See https://github.com/Day8/re-frame/wiki/Using-Handler-Middleware
;;
(defn check-and-throw
  "throw an exception if db doesn't match the schema."
  [a-schema db]
    (if-let [problems (s/check a-schema db)]
      (throw (js/Error. (str "schema check failed: " problems)))))

(def validate-schema-mw
  (after (partial check-and-throw schema)))

;; -- Handlers --------------------------------------------------------------

(register-handler
  :initialize-db
  validate-schema-mw
  (fn [_ _]
    app-db))

(register-handler
  :set-greeting
  validate-schema-mw
  (fn [db [_ value]]
    (assoc db :greeting value)))