Miles to go …

April 29, 2009

TOTD #80: Sinatra CRUD application using Haml templates with JRuby and GlassFish Gem

Filed under: glassfish, netbeans, sinatra, totd — Tags: , , — arungupta @ 2:00 am

TOTD #79 showed how to run a trivial Sinatra application using GlassFish Gem. Sinatra provides support for Haml, Erb, Builder, Sass, and Inline templates as described here. This TOTD will show how to get started with creating a Sinatra CRUD application using Haml templates.

Haml is based on one primary principle – Markup should be beautiful because beauty makes you faster.

Get started by installing the Haml gem as:

/tools/jruby-1.2.0 >./bin/jruby -S gem install haml –no-ri –no-rdoc
JRuby limited openssl loaded. gem install jruby-openssl for full support.
Successfully installed haml-2.0.9
1 gem installed

And follow the tutorial, documentation, and reference page for more details.

Sinatra is ORM-agnostic and so any Ruby ORM framework such as ActiveRecord, DataMapper, Sequel, and others. DataMapper with JRuby requires work so this TOTD will show how to use ActiveRecord instead. There is sinatras-hat which allows to create RESTy CRUD apps with Sinatra. There probably are mutiple other ways to create this application but I prefer to understanding the wiring so this blog will use a bare minimal structure.

Anyway, lets get started!

  1. Create the database as:

    ~/tools/jruby/samples/sinatra-sample >mysql –user root
    Welcome to the MySQL monitor.  Commands end with ; or \g.
    Your MySQL connection id is 664
    Server version: 5.1.30 MySQL Community Server (GPL)

    Type ‘help;’ or ‘\h’ for help. Type ‘\c’ to clear the buffer.

    mysql> create database hello_development;
    Query OK, 1 row affected (0.00 sec)

    mysql> use hello_development;
    Database changed
    mysql> CREATE TABLE `runners` (`id` int(11) DEFAULT NULL auto_increment PRIMARY KEY, `distance` float, `minutes` int(11), `created_at` datetime, `updated_at` datetime);             
    Query OK, 0 rows affected (0.06 sec)

  2. Update “hello.rb” from TOTD #79 such that it looks like:
    require ‘rubygems’
    require ’sinatra’
    require ‘activerecord’

    ## Setup

      :adapter  => “jdbcmysql”,
      :host     => “localhost”,
      :username => “root”,
      :password => “”,
      :database => “hello_development”

    ## Models

    class Runner < ActiveRecord::Base

    ## Controller Actions

    get ‘/hi’ do
      “Hello World!”

    get ‘/’ do
      @runner = Runner.find(:all)
      haml :index

    get ‘/new’ do
      haml :new

    get ‘/:id’ do
      @runner = Runner.find(params[:id])
      if (@runner)
        haml :show
        redirect ‘/’

    post ‘/’ do
      @runner = => params[:distance], :minutes => params[:minutes])
        redirect “/#{}”
        redirect ‘/’

    Firstly, it pulls in the ActiveRecord dependency. Then “ActiveRecord::Base.establish_connection” is used to establish a connection with the previously created database. “Runner” is tagged as a model class by inheriting from “ActiveRecord::Base” and uses the default table name (“runners” in this case). Add four new methods:

    1. Three GET methods to show all the runners, a form to enter new data, and show a particular log entry. Each method requires a HAML template (will be created in next step) to render the information.
    2. One POST method to save the newly created log entry in the database.
  3. Create a new directory “views” and create the following files in that directory. Each file serves as a view and rendered from an action in “hello.rb”.
    1. “index.haml”: Show all the runners

      %h1 Listing all runners …
          %th Distance
          %th Minutes
        – @runner.each do |r|
            %td= r.distance
            %td= r.minutes
        New Runner

    2. “new.haml”: Enter a new entry
      %h1 Adding a new runner log …
      %form{:method=>”post”, :action=>”/”}
        %input{:type=>”text”, :name=>”distance”}
        %input{:type=>”text”, :name=>”minutes”}
        %input{:type=>”submit”, :value=>”Submit”}

    3. “show.haml”: Show a particular log entry
      %h1 Showing a runner log …

      = @runner.distance
      = @runner.minutes
      %a{:href=>”/”}= “Show All!”

      The complete directory structure looks like:


That’s it, now run the application as:

~/tools/jruby/samples/sinatra-sample >../../bin/jruby -S glassfish
Starting GlassFish server at: in development environment…
Writing log messages to: /Users/arungupta/tools/jruby-1.2.0/samples/sinatra-sample/log/development.log.
Press Ctrl+C to stop.

The main page is available at “http://localhost:3000/” and looks like:

Clicking on “New Runner” gives …

Enter the data, and click on “Submit” to show …

Click on “Show All!” to see all the entries added so far …

And after adding few entries the main page looks like …

This application shows Create and Read from the CRUD, it’s fairly easy to add Update and Delete functionality as well but that’s an excercise left for the readers :-)

You’ll hear all about it at Develop with Pleasure, Deploy with Fun: GlassFish and NetBeans for a Better Rails Experience at Rails Conf next week.

Technorati: totd glassfish jruby sinatra crud

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