Arun Gupta, Miles to go ...

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

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. http://wiki.jruby.org/wiki/JRuby_Builtin_OpenSSL Successfully installed haml-2.0.9 1 gem installed And follow the tutorial, documentation, and reference page for more details.

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 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
   
   

   %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
   
   

   %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
   
   

   %h1 Showing a runner log ... Distance: = @runner.distance %br Minutes: = @runner.minutes %br %br %a{:href=>"/"}= "Show All!"

   
   The complete directory structure looks like:
   
   

   . ./hello.rb ./views ./views/index.haml ./views/new.haml ./views/show.haml

Posted by Arun Gupta in web2.0  |  Comments[5]