follow best practices of re-frame and give an app-db a schema

re-natal.coffee

@@ -232,11 +232,14 @@ init = (projName) ->
 
     handlersPath = "src/#{projNameUs}/handlers.cljs"
     subsPath = "src/#{projNameUs}/subs.cljs"
+    dbPath = "src/#{projNameUs}/db.cljs"
     exec "cp #{resources}cljs/handlers.cljs #{handlersPath}"
     exec "cp #{resources}cljs/subs.cljs #{subsPath}"
+    exec "cp #{resources}cljs/db.cljs #{dbPath}"
 
     edit handlersPath, [[projNameHyphRx, projNameHyph], [projNameRx, projName]]
     edit subsPath, [[projNameHyphRx, projNameHyph], [projNameRx, projName]]
+    edit dbPath, [[projNameHyphRx, projNameHyph], [projNameRx, projName]]
 
     fs.mkdirSync 'src/cljsjs'
     exec "echo '(ns cljsjs.react)' > src/cljsjs/react.cljs"
@@ -283,8 +286,7 @@ init = (projName) ->
     exec 'npm i'
 
     fs.unlinkSync '.gitignore'
-    exec "
-           node -e
+    exec "node -e
            \"require('react-native/local-cli/cli').init('.', '#{projName}')\"
            "
 

resources/cljs/db.cljs

@@ -0,0 +1,8 @@
+(ns $PROJECT_NAME_HYPHENATED$.db
+  (:require [schema.core :as s :include-macros true]))
+
+;; schema of app-db
+(def schema {:greeting s/Str})
+
+;; initial state of app-db
+(def app-db {:greeting "Hello Clojure in iOS and Android!"})

resources/cljs/handlers.cljs

@@ -1,15 +1,32 @@
 (ns $PROJECT_NAME_HYPHENATED$.handlers
   (:require
-    [re-frame.core :refer [register-handler path trim-v after dispatch]]))
+    [re-frame.core :refer [register-handler after]]
+    [schema.core :as s :include-macros true]
+    [$PROJECT_NAME_HYPHENATED$.db :refer [app-db schema]]))
 
-(def app-db {:greeting "Hello Clojure in iOS and Android!"})
+;; -- 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)))

resources/project.clj

@@ -6,7 +6,8 @@
             :dependencies [[org.clojure/clojure "1.7.0"]
                            [org.clojure/clojurescript "1.7.170"]
                            [reagent "0.5.1" :exclusions [cljsjs/react]]
-                           [re-frame "0.5.0"]]
+                           [re-frame "0.6.0"]
+                           [prismatic/schema "1.0.4"]]
             :plugins [[lein-cljsbuild "1.1.1"]
                       [lein-figwheel "0.5.0-2"]]
             :clean-targets ["target/" "index.ios.js" "index.android.js"]