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

href="http://blog.arungupta.me/2009/04/27/totd-79-getting-started-with-sinatra-applications-on-jruby-and-glassfish-gem.aspx">TOTD
#79 showed how to run a trivial href="http://www.sinatrarb.com/">Sinatra
application using href="http://rubyforge.org/projects/glassfishgem/">GlassFish
Gem. Sinatra
provides support for Haml,
Erb,
Builder,
Sass,
and Inline templates as href="http://www.sinatrarb.com/intro.html">described here.
This TOTD will show how to get started with creating a Sinatra CRUD
application using Haml templates.

And follow the tutorial,
documentation,
and href="http://haml.hamptoncatlin.com/docs/rdoc/classes/Haml.html">reference
page for more details.

Sinatra is ORM-agnostic and so any Ruby ORM framework such as href="http://api.rubyonrails.org/classes/ActiveRecord/Base.html">ActiveRecord,
DataMapper,
Sequel,
and others. DataMapper with JRuby href="http://www.datamapper.org/doku.php?id=jruby:contribute">requires
work so this TOTD will show how to use ActiveRecord instead.
There is href="http://github.com/nakajima/sinatras-hat/tree/master">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:
   
   
   
   style="text-align: left; background-color: rgb(204, 204, 255); width: 100%;"
   cellpadding="2" cellspacing="2">
   ~/tools/jruby/samples/sinatra-sample > style="font-weight: bold;">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 href="http://blog.arungupta.me/2009/04/27/totd-79-getting-started-with-sinatra-applications-on-jruby-and-glassfish-gem.aspx">TOTD
   #79 such that it looks like:
   
   
   
   style="text-align: left; background-color: rgb(204, 204, 255); width: 100%;"
   cellpadding="2" cellspacing="2">
   require 'rubygems'
   
   require 'sinatra'
   
   require 'activerecord'
   
   
   
   ## Setup
   
   
   
   ActiveRecord::Base.establish_connection(
   
     :adapter  => "jdbcmysql",
   
     :host     =>
   "localhost",
   
     :username => "root",
   
     :password => "",
   
     :database => "hello_development"
   
   )
   
   
   
   ## Models
   
   
   
   class Runner < ActiveRecord::Base
   
   end
   
   
   
   ## Controller Actions
   
   
   
   get '/hi' do
   
     "Hello World!"
   
   end
   
   
   
   get '/' do
   
     @runner = Runner.find(:all)
   
     haml :index
   
   end
   
   
   
   get '/new' do
   
     haml :new
   
   end
   
   
   
   get '/:id' do
   
     @runner = Runner.find(params[:id])
   
     if (@runner)
   
       haml :show
   
     else
   
       redirect '/'
   
     end
   
   end
   
   
   
   post '/' do
   
     @runner = Runner.new(:distance => params[:distance],
   :minutes => params[:minutes])
   
     if @runner.save
   
       redirect "/#{@runner.id}"
   
     else
   
       redirect '/'
   
     end
   
   end
   

   
   
   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
   
   
   
   style="text-align: left; background-color: rgb(204, 204, 255); width: 100%;"
   cellpadding="2" cellspacing="2">
   %h1 Listing all runners ...
   
   %table
   
     %tr
   
       %th Distance
   
       %th Minutes
   
     - @runner.each do |r|
   
       %tr
   
         %td= r.distance
   
         %td= r.minutes
   
   %br
   
   %a{:href=>"/new"}
   
     New Runner

   
   

2. "new.haml": Enter a new entry
   
   
   
   style="text-align: left; background-color: rgb(204, 204, 255); width: 100%;"
   cellpadding="2" cellspacing="2">
   %h1 Adding a new runner log ...
   
   %form{:method=>"post", :action=>"/"}
   
     Distance:
   
     %input{:type=>"text", :name=>"distance"}
   
     %br
   
     Minutes:
   
     %input{:type=>"text", :name=>"minutes"}
   
     %br
   
     %input{:type=>"submit", :value=>"Submit"}
   
     %br

   
   

3. "show.haml": Show a particular log entry
   
   
   
   style="text-align: left; background-color: rgb(204, 204, 255); width: 100%;"
   cellpadding="2" cellspacing="2">
   %h1 Showing a runner log ...
   
   Distance:
   
   = @runner.distance
   
   %br
   
   Minutes:
   
   = @runner.minutes
   
   %br
   
   %br
   
   %a{:href=>"/"}= "Show All!"

   
   
   The complete directory structure looks like:
   
   
   

   style="text-align: left; background-color: rgb(204, 204, 255); width: 100%;"
   cellpadding="2" cellspacing="2">
   .
   
   ./hello.rb
   
   ./views
   
   ./views/index.haml
   
   ./views/new.haml
   
   ./views/show.haml

That's it, now run the application as: