From 573594f80d3345d32c23d05c302414bd209c2314 Mon Sep 17 00:00:00 2001
From: q <huu2uan@gmail.com>
Date: Thu, 22 Feb 2024 15:51:13 +0700
Subject: [PATCH] Update part4

---
 doc/clj-web-from-the-ground-up-4.md | 101 ++++++++++++----------------
 project.clj                         |   6 +-
 2 files changed, 46 insertions(+), 61 deletions(-)

diff --git a/doc/clj-web-from-the-ground-up-4.md b/doc/clj-web-from-the-ground-up-4.md
index 633a890..3223580 100644
--- a/doc/clj-web-from-the-ground-up-4.md
+++ b/doc/clj-web-from-the-ground-up-4.md
@@ -2,85 +2,70 @@ add db layer
 
 add deps
 ```
-[org.clojure/java.jdbc "0.7.9"]
-[com.h2database/h2 "1.4.199"]
-[com.mchange/c3p0 "0.9.5.4"]
+[com.github.seancorfield/next.jdbc "1.3.909"]
+[com.h2database/h2 "2.2.224"]
+[com.zaxxer/HikariCP "5.1.0"]
 ```
 
-`db.clj`
-```clj
-(ns clj-web.db
-  (:require [com.stuartsierra.component :as component])
-  (:import (com.mchange.v2.c3p0 ComboPooledDataSource)))
-
-(def db-spec
-  {:classname   "org.h2.Driver"
-   :subprotocol "h2:mem"                  ; the prefix `jdbc:` is added automatically
-   :subname     "demo;DB_CLOSE_DELAY=-1"  ; `;DB_CLOSE_DELAY=-1` very important!!!
-                    ; http://www.h2database.com/html/features.html#in_memory_databases
-   :user        "sa"                      ; default "system admin" user
-   :password    ""                        ; default password => empty string
-   })
+`next.jdbc` has support for Component built-in, via the `next.jdbc.connection/component` function which creates a Component-compatible entity which you can start and then invoke as a function with no arguments to obtain the DataSource within.
 
-(defrecord Database [db-spec datasource]
-  component/Lifecycle
-  (start [this]
-    (let [cpds (doto (ComboPooledDataSource.)
-                 (.setDriverClass (:classname db-spec))
-                 (.setJdbcUrl (str "jdbc:" (:subprotocol db-spec) ":" (:subname db-spec)))
-                 (.setUser (:user db-spec))
-                 (.setPassword (:password db-spec))
-               ;; expire excess connections after 30 minutes of inactivity:
-                 (.setMaxIdleTimeExcessConnections (* 30 60))
-               ;; expire connections after 3 hours of inactivity:
-                 (.setMaxIdleTime (* 3 60 60)))]
-      (assoc this :datasource cpds)))
-  (stop [this]
-    (.close datasource)
-    (assoc this :datasource nil)))
-
-(defn new-database []
-  (map->Database {:db-spec db-spec}))
-```
+then, we refactor `core.clj` into `app.clj` & `main.clj`
 
 `app.clj`
 ```clj
 (ns clj-web.app
-  (:require [compojure.core :refer :all]
-            [compojure.route :as route]
-            [com.stuartsierra.component :as component]
-            [ring.middleware.defaults :refer :all]
-            [clojure.java.jdbc :as jdbc]))
+  (:require [com.stuartsierra.component :as component]
+            [next.jdbc :as jdbc]
+            [reitit.ring :as ring]))
+
+(defn ok-handler [_]
+  {:status 200, :body "ok"})
 
-(defn app-routes [db]
-  (routes
-   (GET "/" [] "Hello World!")
-   (GET "/db" [] {:status 200
-                  :headers {"Content-Type" "text/html"}
-                  :body (jdbc/query db ["SELECT 3*5 AS result"])})
-   (route/not-found "404")))
+(defn db-handler [req db]
+  {:status 200, :body (prn-str (jdbc/execute! (db) ["SELECT 3*5 AS result"]))})
+
+(defn app-handler [db]
+  (ring/ring-handler
+    (ring/router
+      [["/" ok-handler]
+       ["/db" #(db-handler % db)]])
+    (ring/create-default-handler)))
 
 (defrecord App [handler db]
   component/Lifecycle
   (start [this]
-    (assoc this :handler (-> (handler db)
-                             (wrap-defaults site-defaults))))
+    (assoc this :handler (handler db)))
   (stop [this]
     (assoc this :handler nil)))
 
 (defn new-app []
-  (map->App {:handler app-routes}))
+  (map->App {:handler app-handler}))
 ```
 
-system
+`main.clj`
 ```clj
+(ns clj-web.main
+  (:gen-class)
+  (:require [ring.component.jetty :refer [jetty-server]]
+            [com.stuartsierra.component :as component]
+            [next.jdbc.connection :as connection]
+            [clj-web2.app :refer [new-app]])
+  (:import (com.zaxxer.hikari HikariDataSource)))
+
+(def db-spec {:dbtype "h2" :dbname "example"})
+
 (defn app-system
   []
   (-> (component/system-map
-       :db (new-database)
-       :app (new-app)
-       :http (jetty-server {:port 3000}))
+        :db (connection/component HikariDataSource db-spec)
+        :app (new-app)
+        :http (jetty-server {:port 3000}))
       (component/system-using
-       {:http [:app]
-        :app [:db]})))
+        {:http [:app]
+         :app [:db]})))
+
+(defn -main
+  "I don't do a whole lot ... yet."
+  [& args]
+  (component/start (app-system)))
 ```
diff --git a/project.clj b/project.clj
index 75fce47..5eadb26 100644
--- a/project.clj
+++ b/project.clj
@@ -16,9 +16,9 @@
                  ; config
                  [aero "1.1.3"]
                  ; db
-                 [org.clojure/java.jdbc "0.7.9"]
-                 [com.h2database/h2 "1.4.199"]
-                 [com.mchange/c3p0 "0.9.5.4"]
+                 [com.github.seancorfield/next.jdbc "1.3.909"]
+                 [com.h2database/h2 "2.2.224"]
+                 [com.zaxxer/HikariCP "5.1.0"]
                  ; logging
                  [org.clojure/tools.logging "0.5.0"]
                  [ch.qos.logback/logback-classic "1.2.3"]]