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Tutorial 1 - Clojure Web Application Using Noir

I am going to do a series of blog posts on using Noir framework to create a simple website. Here is part 1 of the tutorial.

We are going to cover following points in this tutorial :

Now we will create a simple finance manager blog.

The easiest way to get Noir setup is to use Leiningen. Then execute Following Command In Terminal

$ lein new noir finance_manager
Generating a lovely new Noir project named testing...

The above command create a finance_manager website in a specified directory.

Created website has following structure :-

       /finance_manager
          --resources/
           --public/
               --css/reset.css
               --img/
               --js/
           --src/
             --finance-manager/
             --models/
             --views/ common.clj
                     welcome.clj
             server.clj
           --test/
             --finance_manager/
          project.clj
          README.md

The project.clj file is used for building the application and managing dependencies by Leiningen.

Under the src folder, we have the folder finance_manager which contains server.clj. This file contains the entry point to our application. It loads up all the views and provides a main function which can be used to start the application.

The models folder is used to keep the data such as code for the database access and table management. The views folder contains the namespaces describing the pages of our application and their supporting code. The template contains common.clj which provides a basic layout and any code shared between the pages. The welcome.clj is the namespace where an example page is defined and you can create your own pages under this namespace.

The resource/public folder contains the stylesheets and javasript.

Execute the following command :-

       $ lein run   
       Starting server...
       2012-08-16 09:39:22.479:INFO::Logging to STDERR via org.mortbay.log.StdErrLog
       Server started on port [8080].
       You can view the site at http://localhost:8080
       #<Server Server@2206270b>
       2012-08-16 09:39:22.480:INFO::jetty-6.1.25
       2012-08-16 09:39:22.521:INFO::Started SocketConnector@0.0.0.0:8080

lein run run the -main function in our finance_manager namespace.

Open the browser and run :-

      localhost:8080

For creating pages :-

Open src/views/welcome.clj file. And create a homepage of the website.

For creating pages defpage macro is used which create a Compojure route for the specified url. defpage has following syntax.

  (defpage url params content)
  (defpage "/homepage" []
  [:h3 "Finance Manager"])

Open the browser and run the following

  localhost:8080/homepage

Design a form which will provide the User Interface to add the Monthly Budget.

  (defpage "/addbudget" {:keys [error]}
   (common/layout
     [:h2 "Add Monthly Budget"]
     [:div.error error]
     (form-to [:post "/addbudget"]
        (label "budget_date" "Select Budget Date")
        (text-field "budget_date")
        [:br]
        (label "budget_amt" "Budget Amount")
        (text-field "budget_amt")
        [:br]
        (submit-button "Add Budget")
        (reset-button "Cancel")
     )
   )
)

Design the another page for POST which contain the server code to handle the input coming from addbudget page.

 (defpage [:post "/addbudget"] budget
   (common/layout
     [:div (:budget_date budget)]
     [:div (:budget_amt budget)]
   )
 )

The above page simply display the values enter by the user on the page.

Open the browser and run

  localhost:8080/addbudget

This will display the page containing UI to add budget values.

To save the values in the database we have to create the databse and setup the connection with the database.

Follow the following steps for Database Access.

There are several Clojure libraries availale for dealing with databse. In this tutorial we are using clojure.data.jdbc and MySql databse.

We will create a new namespace under the src/finance_manager/models. We call this namespace db. The namespace will live in a file called db.clj under src/finance_manager/models directory.

(ns finance_manager.models.db)

(require '[clojure.java.jdbc :as sql])

Now we will define our database connection in this file.

(def db
  {:subprotocol "mysql"
   :subname "//localhost:3306/finance_manager_db"
   :user "username"
   :password "private"})

Now add dependencies in project.clj file for database connection.

[org.clojure/java.jdbc "0.2.3"]
[mysql/mysql-connector-java "5.1.6"]

Create a table for budget in finance_manager_db

(defn create-budget-table []
  (sql/with-connection
      db
      (sql/create-table
        :budget
        [:id :serial "PRIMARY KEY"]
        [:budget_date "date"]
        [:budget_amt "double"]
      )
    )
)

Now open src/finance_manager/server.clj file.

Write a function that call this create-budget-table function. and call that function in -main function.

(:require [finance_manager.models.db :as db])
(defn init
  []
  (db/create-budget-table)
)

(defn -main []
  (init))

Now start REPL session and execute following command in it.

$ lein repl
nREPL server started on port 53376
REPL-y 0.1.9
Clojure 1.4.0
    Exit: Control+D or (exit) or (quit)
Commands: (user/help)
    Docs: (doc function-name-here)
          (find-doc "part-of-name-here")
  Source: (source function-name-here)
          (user/sourcery function-name-here)
 Javadoc: (javadoc java-object-or-class-here)
Examples from clojuredocs.org: [clojuredocs or cdoc]
          (user/clojuredocs name-here)
          (user/clojuredocs "ns-here" "name-here")
finance_manager.server=>

finance_manager.server=> (finance_manager.server/-main)

(finance_manager.server/-main) it will execute the -main function and create a budget table in database.

Now open src/finance_manager/models/db.clj file and write the function to add the budget record in the budget table.

(defn add-budget [budget]
  (sql/with-connection
    db
    (sql/insert-record :budget budget)
  )
)

Now modify our [:post "/addbudget"] page to insert budget record.

(defpage [:post "/addbudget"] budget
 (let
     (try
       (db/add-budget budget)
             (resp/redirect "/homepage")
             (catch Exception ex
               (render "/addbudget" (assoc budget :error (.getMessage ex)))
             )
     )
  )
)

Now create a page that will display list of all added budgets.

So first write a function in src/finance_manager/models/db.clj file to get all records from database.

  (defn db-read [query & args]
  (sql/with-connection
    db
    (sql/with-query-results
      res
      (vec (cons query args)) (doall res))))
(defpage "/viewbudget" []
 (common/layout
    (let [budget (db/db-read "select * from budget")]
    (html
      [:h3 "Budget List Page"]
      [:table{:border="1"}
       [:tr
        [:th "Budget ID"]
        [:th "Budget Date"]
        [:th "Budget Amount"]
       ]
       (for [bgt budget]
        [:tr
          [:td (:id bgt)]
          [:td (:budget_date bgt)]
          [:td (:budget_amt bgt)]
         ]
       )]
     )
   )
  )
)

Now add links on homepage to add the budget and to view the budget.

 (:use  hiccup.element)

 (defpage "/homepage" []
  (common/layout
    [:h3 "Finance Manager"]
    (html
      (link-to "/adbudget" "Add Budget")
      [:br]
      (link-to "/viewbudget" "View Budget")
    ) 
  )
)

You can also check for following :