Ruby on Rails

Rapid and Sustainable Web Development

Frank S. Kim

betweenGo

Ruby on Rails

• Ruby
• MVC framework
• DRY (Don't Repeat Yourself)
• instant feedback
• code generators, AJAX support, integrated web services support, etc.
• built-in testing framework
• tournament sign-up application

Ruby

• interpreted scripting language
• portable, available on most operating systems
• free, which means not only free of charge, but also freedom to use, copy, modify, and distribute it
• pure object oriented language, all data is an object
• very lax rules when it comes to syntax
• for more info: What's Ruby

Ruby

• concise w/o being unintelligly terse
• metaprogramming, easy to create methods that act almost like extensions to the syntax (domain-specific language)

class Project < ActiveRecord::Base
  belongs_to               :portfolio
  has_one                  :project_manager
  has_many                 :milestones
  has_and_belongs_to_many  :categories
  validates_presence_of    :name, :description
  vaidates_acceptance_of   :non_disclosure_ageement
  valdates_uniqueness_of   :key
  attr_accessor            :password
end
  

Model-View-Controller Architecture

model, state of the application view, how the user interacts with the application controller, receives input from user, interacts with model, and displays appropriate view Rails enforces MVC structure

Don't Repeat Yourself

• single language from top to bottom
• convention over configuration
• Rails shuns configuration files and annotations in favor of reflection and run-time extensions
• no XML

  def set_user_city_state(zipcode)
    zipcode_info = Zipcode.find_by_zipcode zipcode
    ...
  end
  

Instant Feedback

• code changes are immediately available
• no compilation phase
• deployment is trivial

Goodies

• code generators
• AJAX support (e.g. GMail)
• integrated web services support
• reception of incoming e-mails

Testing Framework

• integrated
• isolated environments for development, testing, production
• unit tests (like JUnit)
• functional tests (like Cactus)
• mock objects (e.g. simulate backend system)

Tournament Application - Create

• simple web application for signing up for a basketball tournament
• issue rails command to create application
• start WEBrick server to see application

C:\cygwin\home\Fkim>rails nktournament
      create
      create  app/controllers
      create  app/helpers
      create  app/models
      create  app/views/layouts
      create  config/environments
      create  components
      create  db
      create  doc
      create  lib
      create  lib/tasks
      create  log
      create  public/images
      create  public/javascripts
      create  public/stylesheets
      create  script/performance
      create  script/process
      create  test/fixtures
      create  test/functional
      create  test/mocks/development
      create  test/mocks/test
      create  test/unit
      create  vendor
      create  vendor/plugins
      create  Rakefile
      create  README
      create  app/controllers/application.rb
      create  app/helpers/application_helper.rb
      create  test/test_helper.rb
      create  config/database.yml
      create  config/routes.rb
      create  public/.htaccess
      create  config/boot.rb
      create  config/environment.rb
      create  config/environments/production.rb
      create  config/environments/development.rb
      create  config/environments/test.rb
      create  script/about
      create  script/breakpointer
      create  script/console
      create  script/destroy
      create  script/generate
      create  script/performance/benchmarker
      create  script/performance/profiler
      create  script/process/reaper
      create  script/process/spawner
      create  script/process/spinner
      create  script/runner
      create  script/server
      create  script/plugin
      create  public/dispatch.rb
      create  public/dispatch.cgi
      create  public/dispatch.fcgi
      create  public/404.html
      create  public/500.html
      create  public/index.html
      create  public/favicon.ico
      create  public/robots.txt
      create  public/javascripts/prototype.js
      create  public/javascripts/effects.js
      create  public/javascripts/dragdrop.js
      create  public/javascripts/controls.js
      create  doc/README_FOR_APP
      create  log/server.log
      create  log/production.log
      create  log/development.log
      create  log/test.log

C:\cygwin\home\Fkim>cd nktournament
    

Tournament Application - Database

• create database for tournament
• create SQL script in db directory for teams table and execute it

CREATE TABLE teams (
	id	int unsigned NOT NULL AUTO_INCREMENT,
	name			varchar(64) NOT NULL,
	organization		varchar(64) NOT NULL,
	captain_first_name	varchar(64) NOT NULL,
	captain_last_name	varchar(64) NOT NULL,
	email			varchar(64) NOT NULL,
	PRIMARY KEY (id),
	UNIQUE KEY name (name)
) TYPE=InnoDB;
  

C:\cygwin\home\Fkim\nktournament>mysql < db\teams.sql
    

Tournament Application - Teams

• configure application about which database to use and then restart application
• run code generator to create pages for listing, viewing, creating, and deleting teams

[config/database.yml]

development:
  adapter: mysql
  database: kimplicity
  username: shawn
  password: becker
  socket: /path/to/your/mysql.sock
  

C:\cygwin\home\Fkim\nktournament>ruby script\generate scaffold Team Team
      exists  app/controllers/
      exists  app/helpers/
      create  app/views/team
      exists  test/functional/
  dependency  model
      exists    app/models/
      exists    test/unit/
      exists    test/fixtures/
      create    app/models/team.rb
      create    test/unit/team_test.rb
      create    test/fixtures/teams.yml
      create  app/views/team/_form.rhtml
      create  app/views/team/list.rhtml
      create  app/views/team/show.rhtml
      create  app/views/team/new.rhtml
      create  app/views/team/edit.rhtml
      create  app/controllers/team_controller.rb
      create  test/functional/team_controller_test.rb
      create  app/helpers/team_helper.rb
      create  app/views/layouts/team.rhtml
      create  public/stylesheets/scaffold.css

C:\cygwin\home\Fkim\nktournament>ruby script\server
=> Booting WEBrick...
=> Rails application started on http://0.0.0.0:3000
=> Ctrl-C to shutdown server; call with --help for options
[2005-11-13 13:20:13] INFO  WEBrick 1.3.1
[2005-11-13 13:20:13] INFO  ruby 1.8.2 (2004-12-25) [i386-mswin32]
[2005-11-13 13:20:13] INFO  WEBrick::HTTPServer#start: pid=5688 port=3000
    

Tournament Application - Validation

• validate that all fields are entered
• validate that email address is the correct format

[app/model/team.rb]

class Team < ActiveRecord::Base

  validates_presence_of :name, :organization,
      :captain_first_name, :captain_last_name, :email

  validates_format_of :email,
      :with => /^([^@\s]+)@((?:[-a-z0-9]+\.)+[a-z]{2,})$/

end
  

Tournament Application - Players

• create SQL script in db directory for players table and execute it
• run code generator to create pages for listing, viewing, creating, and deleting players

CREATE TABLE players (
	id	int unsigned NOT NULL AUTO_INCREMENT,
	team_id			int unsigned NOT NULL,
	first_name		varchar(64) NOT NULL,
	last_name		varchar(64) NOT NULL,
	PRIMARY KEY (id)
) TYPE=InnoDB;
  

C:\cygwin\home\Fkim\nktournament>mysql < db\players.sql

C:\devel\web\nktournament>ruby script\generate model player
      exists  app/models/
      exists  test/unit/
      exists  test/fixtures/
      create  app/models/player.rb
      create  test/unit/player_test.rb
      create  test/fixtures/players.yml
    

Tournament Application - Association

• each team has many players and each player belongs to one team

[app/model/team.rb]

class Team < ActiveRecord::Base
  has_many :players
  ...
end

[app/model/player.rb]

class Player < ActiveRecord::Base
  belongs_to :teams
  validates_presence_of :first_name, :last_name
end
  

Tournament Application - Team Players

• list players on team page

[app/views/team/show.rhtml]

<b>Players</b>

<table>
<% for player in @team.players %>
  <tr>
    <td>
      <%=h player.first_name %> <%=h player.last_name %>
    </td>
  </tr>
<% end %>
</table>
  

Tournament Application - Add Player I

• add a player to a team

[app/views/team/show.rhtml]

<%= link_to 'Add Player', :action => 'add_player', :id => @team %> |

[app/controllers/team_controller.rb]

  def add_player
    @player = Player.new
  end
  

Tournament Application - Add Player II

[app/views/team/add_player.rhtml]

<h1>Add Player</h1>

<%= start_form_tag :action => 'add_player' %>
  <%= error_messages_for 'player' %>

  <p><label for="player_first_name">First Name</label><br/>
  <%= text_field 'player', 'first_name'  %></p>

  <p><label for="player_last_name">Last Name</label><br/>
  <%= text_field 'player', 'last_name'  %></p>

  <input type="hidden" name="id" value="#{@team}"/>
  <%= submit_tag 'Add Player' %>
<%= end_form_tag %>
<%= link_to 'Back', :action => 'show', :id => @team %>
  

Tournament Application - Add Player III

[app/controllers/team_controller.rb]
  def add_player
    case @request.method; when :get
      @team = Team.find(params[:id])
      @player = Player.new
    when :post
      @team = Team.find(params[:id])
      @player = Player.new(params[:player])
      @team.players << @player
      if @team.save
        flash[:notice] = 'Player was successfully added.'
        redirect_to :action => 'show', :id => params[:id]
      else
        render :action => 'add_player'
      end
    end
  end
  

Problems

• Rails is still in development and has not reached version 1.0. Bugs and upgrade issues still exist.
• online documentation is good but incomplete and sometimes contradicting, get Agile Web Development with Rails
• personalization and commerce frameworks are not part of Rails
• code generators do not have a merge function

Credits

• Agile Web Development with Rails
• Ruby on Rails
• What is Ruby on Rails
• Ruby
• Metaprogramming Ruby
• S5: A Simple Standards-Based Slide Show System