Ruby On Rails Introduction

Damian Garcia

“ Building good software is not always easy, but implementing agile practices with the Ruby language and the Rails framework can greatly simplify the process.”

Agile Development Iterative Development Open Collaboration Adaptability

Iterative Development Working software is delivered to the client at regular, short intervals . Client feedback is used to make changes to the software specifications at any stage in the development. The client is asked to be fully engaged throughout the development process.

Unrestricted communication between programmers and clients. Face to face communication is preferred over specification documents. The client can makes changes at anytime, and the website can even be tested in production mode to get user feedback . Open Collaboration

Changes to the software specifications are welcome even in late stages of development. Adaptability

How is it possible with Rails ?

Agile software development movement and Rails go hand in hand . Rails has many facilities to aid agile development of applications.

Rails way

Ruby MVC COC DRY ReST RIA-Web 2.0 TDD/BDD Version Control Capistrano

One Language: Ruby

Making programming truly fun ...

10. times do puts "hola" end an_array. group_by {|a| a. type } objects. each do |obj| e. save! end [1,2,3,4,5,6,7]. select {|x| x % 2 == 0} File. open ("config.txt") do |in| in. each_line do |line| process_config_line(line) ‏ end end Making programming truly fun ...

10. times do puts "hola" end an_array. group_by {|a| a. type } objects. each do |obj| e. save! end [1,2,3,4,5,6,7]. select {|x| x % 2 == 0} File. open ("config.txt") do |in| in. each_line do |line| process_config_line(line) ‏ end end Making programming truly fun ... class Product < ActiveRecord::Base belogns_to :manufacturer has_many :components validates_presence_of :name , :price validates_length_of :name , :maximum => 35 after_save :call_some_method end In Rails:

“ Ruby” and “Ruby on Rails” are not the same thing

“ Ruby” and “Ruby on Rails” are not the same thing Ruby A Programming Language 1993 by Yukihiro “Matz” Matsumoto

“ Ruby” and “Ruby on Rails” are not the same thing Ruby A Programming Language 1993 by Yukihiro “Matz” Matsumoto Ruby on Rails Web Application Framework written in Ruby 2004 by David Heinemeier Hansson

Ruby is an Object Oriented scripting language. Clean syntax. Easy to learn. Less and more redeable code. Principle of Least Surprise (POLS) ‏ . Shorter development times. Simple but powerful. No compilation cycle.

Easy to Learn

Everything in Rails is Ruby code ( SQL and JavaScript are abstracted) ‏

“ Ruby successfully combines Smalltalk's conceptual elegance, Python's ease of use and learning, and Perl's pragmatism.” Curt Hibbs (O'Reilly Author) ‏ “ You can express ideas naturally and cleanly in Ruby code. This leads to programs that are easy to write and (just as importantly) are easy to read months later.” Dave Thomas (Agile Web Development with Rails) ‏

Rails is an MVC web framework where M odels, v iews, and c ontrollers are fully integrated. You automatically get all the benefits of an MVC design without the hassle of explicitly configuring each component to play well with the others. user@comp:~/$ rails myrailsapp create create app/controllers create app/helpers create app/models create app/views/layouts create config/environments create config/initializers create db create doc create lib create lib/tasks ...

... <% for client in @clients %> <tr> <td><%=h client.name %></td> <td><%=h client.age %></td> </tr> <% end %> ... V app/ views /clients/index.html.erb class Client < ActiveRecord::Base #nothing here end M app/ models /client.rb class ClientsController < ApplicationController def index @clients = Client .find(:all) ‏ respond_to do | format | format.html # index.html.erb format.xml { render :xml => @clients } end end ... end C app/ controllers /clients_controller.rb ... <tr> <td> Damian Garcia </td> <td> 28 </td> </tr> <tr> <td> Gustavo Brey </td> <td> 28 </td> </tr> ... Result http://localhost:3000/clients

Convention over Configuration

Instead of asking questions like: “How do I get function x to call method y?” Developer is able to focus on how to do something He is freed to focus more on the general business logic of the application. Rails uses simple naming conventions and clever use of reflection to make your work easier with near-zero configuration

DRY (Don't Repeat Yourself) ‏

Repeating code as little as possible makes it easier to make changes later on in the development cycle. If the code only exists in one place , it only needs to be changed in one place.

exists app/models/ exists app/controllers/ exists app/helpers/ create app/views/clients exists app/views/layouts/ exists test/functional/ exists test/unit/ exists public/stylesheets/ create app/views/clients/index.html.erb create app/views/clients/show.html.erb create app/views/clients/new.html.erb create app/views/clients/edit.html.erb create app/views/layouts/clients.html.erb identical public/stylesheets/scaffold.css create app/controllers/clients_controller.rb create test/functional/clients_controller_test.rb create app/helpers/clients_helper.rb route map.resources :clients dependency model exists app/models/ exists test/unit/ exists test/fixtures/ create app/models/client.rb create test/unit/client_test.rb create test/fixtures/clients.yml exists db/migrate create db/migrate/20080812145516_create_clients.rb usr@comp:~/myapp$ ruby script/generate scaffold client name:string age:integer comment:text

exists app/models/ exists app/controllers/ exists app/helpers/ create app/views/clients exists app/views/layouts/ exists test/functional/ exists test/unit/ exists public/stylesheets/ create app/views/clients/index.html.erb create app/views/clients/show.html.erb create app/views/clients/new.html.erb create app/views/clients/edit.html.erb create app/views/layouts/clients.html.erb identical public/stylesheets/scaffold.css create app/controllers/clients_controller.rb create test/functional/clients_controller_test.rb create app/helpers/clients_helper.rb route map.resources :clients dependency model exists app/models/ exists test/unit/ exists test/fixtures/ create app/models/client.rb create test/unit/client_test.rb create test/fixtures/clients.yml exists db/migrate create db/migrate/20080812145516_create_clients.rb Where the Templates Go By Convention : usr@comp:~/myapp$ ruby script/generate scaffold client name:string age:integer comment:text

exists app/models/ exists app/controllers/ exists app/helpers/ create app/views/clients exists app/views/layouts/ exists test/functional/ exists test/unit/ exists public/stylesheets/ create app/views/clients/index.html.erb create app/views/clients/show.html.erb create app/views/clients/new.html.erb create app/views/clients/edit.html.erb create app/views/layouts/clients.html.erb identical public/stylesheets/scaffold.css create app/controllers/clients_controller.rb create test/functional/clients_controller_test.rb create app/helpers/clients_helper.rb route map.resources :clients dependency model exists app/models/ exists test/unit/ exists test/fixtures/ create app/models/client.rb create test/unit/client_test.rb create test/fixtures/clients.yml exists db/migrate create db/migrate/20080812145516_create_clients.rb Where the Templates Go Within this directory, the convention is to have a separate subdirectory for the views of each controller By Convention : usr@comp:~/myapp$ ruby script/generate scaffold client name:string age:integer comment:text

exists app/models/ exists app/controllers/ exists app/helpers/ create app/views/clients exists app/views/layouts/ exists test/functional/ exists test/unit/ exists public/stylesheets/ create app/views/clients/index.html.erb create app/views/clients/show.html.erb create app/views/clients/new.html.erb create app/views/clients/edit.html.erb create app/views/layouts/clients.html.erb identical public/stylesheets/scaffold.css create app/controllers/clients_controller.rb create test/functional/clients_controller_test.rb create app/helpers/clients_helper.rb route map.resources :clients dependency model exists app/models/ exists test/unit/ exists test/fixtures/ create app/models/client.rb create test/unit/client_test.rb create test/fixtures/clients.yml exists db/migrate create db/migrate/20080812145516_create_clients.rb Where the Templates Go Within this directory, the convention is to have a separate subdirectory for the views of each controller Each directory contains templates named after the actions in the corresponding controller By Convention : usr@comp:~/myapp$ ruby script/generate scaffold client name:string age:integer comment:text

Active Record doesn't requiere a mapping file. A developer doesn't need to code getters and setters, or even the properties of the class. By Convention , ActiveRecord is able to determine that the Client class will map to the CLIENTS table in the DB, the same with fields in table.

Active Record doesn't requiere a mapping file. A developer doesn't need to code getters and setters, or even the properties of the class. By Convention , ActiveRecord is able to determine that the Client class will map to the CLIENTS table in the DB, the same with fields in table. app/models/client.rb class Client < ActiveRecord :: Base end

Active Record doesn't requiere a mapping file. A developer doesn't need to code getters and setters, or even the properties of the class. By Convention , ActiveRecord is able to determine that the Client class will map to the CLIENTS table in the DB, the same with fields in table. app/models/client.rb class Client < ActiveRecord :: Base end usr@comp:~/myapp$ ruby script/console Loading development environment (Rails 2.3.2) ‏ >>

usr@comp:~/myapp$ ruby script/console Loading development environment (Rails 2.3.2) ‏ >> Active Record doesn't requiere a mapping file. A developer doesn't need to code getters and setters, or even the properties of the class. By Convention , ActiveRecord is able to determine that the Client class will map to the CLIENTS table in the DB, the same with fields in table. app/models/client.rb class Client < ActiveRecord :: Base end

usr@comp:~/myapp$ ruby script/console Loading development environment (Rails 2.1.0) ‏ >> Active Record doesn't requiere a mapping file. A developer doesn't need to code getters and setters, or even the properties of the class. By Convention , ActiveRecord is able to determine that the Client class will map to the CLIENTS table in the DB, the same with fields in table. app/models/client.rb class Client < ActiveRecord :: Base end client1 = Client.create(:name => "Gustavo Brey", :age => "28") ‏

usr@comp:~/myapp$ ruby script/console Loading development environment (Rails 2.1.0) ‏ >> Active Record doesn't requiere a mapping file. A developer doesn't need to code getters and setters, or even the properties of the class. By Convention , ActiveRecord is able to determine that the Client class will map to the CLIENTS table in the DB, the same with fields in table. app/models/client.rb class Client < ActiveRecord :: Base end client1 = Client.create(:name => "Gustavo Brey", :age => "28") ‏ => #<Client id: 2, name: "Gustavo Brey", age: 28, comments: nil, created_at: "2008-08-12 20:23:55", updated_at: "2008-08-12 20:23:55"> >>

usr@comp:~/myapp$ ruby script/console Loading development environment (Rails 2.1.0) ‏ >> Active Record doesn't requiere a mapping file. A developer doesn't need to code getters and setters, or even the properties of the class. By Convention , ActiveRecord is able to determine that the Client class will map to the CLIENTS table in the DB, the same with fields in table. app/models/client.rb class Client < ActiveRecord :: Base end client1 = Client.create(:name => "Gustavo Brey", :age => "28") ‏ => #<Client id: 2, name: "Gustavo Brey", age: 28, comments: nil, created_at: "2008-08-12 20:23:55", updated_at: "2008-08-12 20:23:55"> >> client1.name

usr@comp:~/myapp$ ruby script/console Loading development environment (Rails 2.1.0) ‏ >> Active Record doesn't requiere a mapping file. A developer doesn't need to code getters and setters, or even the properties of the class. By Convention , ActiveRecord is able to determine that the Client class will map to the CLIENTS table in the DB, the same with fields in table. app/models/client.rb class Client < ActiveRecord :: Base end client1 = Client.create(:name => "Gustavo Brey", :age => "28") ‏ => #<Client id: 2, name: "Gustavo Brey", age: 28, comments: nil, created_at: "2008-08-12 20:23:55", updated_at: "2008-08-12 20:23:55"> >> client1.name => "Gustavo Brey"

exists app/models/ exists app/controllers/ exists app/helpers/ create app/views/clients exists app/views/layouts/ exists test/functional/ exists test/unit/ exists public/stylesheets/ create app/views/clients/index.html.erb create app/views/clients/show.html.erb create app/views/clients/new.html.erb create app/views/clients/edit.html.erb create app/views/layouts/clients.html.erb identical public/stylesheets/scaffold.css create app/controllers/clients_controller.rb create test/functional/clients_controller_test.rb create app/helpers/clients_helper.rb route map.resources :clients dependency model exists app/models/ exists test/unit/ exists test/fixtures/ create app/models/client.rb create test/unit/client_test.rb create test/fixtures/clients.yml exists db/migrate create db/migrate/20080812145516_create_clients.rb When you generate a controller Rails also creates a layout for that controller. DRY , use Layouts usr@comp:~/myapp$ ruby script/generate scaffold client name:string age:integer comment:text You have the same look and feel which needs to be repeated in each of the actions rhtml files. The same functionality may appear in multiple places. Multiple pages may contain the same snippets of rendered HTML. When Rails requests to render a template within a controller, it renders the one who you ask for and also render a layout template.

DRY , use Partials Partials ("partial views") are fragments of RHTML that can be inserted into a view. They exist to make the view logic simpler.

DRY , use Partials Partials ("partial views") are fragments of RHTML that can be inserted into a view. They exist to make the view logic simpler. app/views/clients/edit.html.erb <h1>Editing client</h1> <% form_for(@client) do |f| %> <%= f.error_messages %> <p> <%= f.label :name %><br /> <%= f.text_field :name %> </p> <p> <%= f.label :age %><br /> <%= f.text_field :age %> </p> <p> <%= f.label :comments %><br /> <%= f.text_area :comments %> </p> <p> <%= f.submit “Update” %> </p> <% end %> <%= link_to 'Back', clients_path %>

DRY , use Partials Partials ("partial views") are fragments of RHTML that can be inserted into a view. They exist to make the view logic simpler. app/views/clients/edit.html.erb app/views/clients/new.html.erb <h1>Editing client</h1> <% form_for(@client) do |f| %> <%= f.error_messages %> <p> <%= f.label :name %><br /> <%= f.text_field :name %> </p> <p> <%= f.label :age %><br /> <%= f.text_field :age %> </p> <p> <%= f.label :comments %><br /> <%= f.text_area :comments %> </p> <p> <%= f.submit “Update” %> </p> <% end %> <%= link_to 'Back', clients_path %> <h1>New client</h1> <% form_for(@client) do |f| %> <%= f.error_messages %> <p> <%= f.label :name %><br /> <%= f.text_field :name %> </p> <p> <%= f.label :age %><br /> <%= f.text_field :age %> </p> <p> <%= f.label :comments %><br /> <%= f.text_area :comments %> </p> <p> <%= f.submit “Create” %> </p> <% end %> <%= link_to 'Back', clients_path %>

DRY , use Partials Partials ("partial views") are fragments of RHTML that can be inserted into a view. They exist to make the view logic simpler. app/views/clients/edit.html.erb app/views/clients/new.html.erb <h1>Editing client</h1> <%= render :partial => 'form', :locals => {:btn_text => "Update"} %> <%= link_to 'Show', @client %> | <%= link_to 'Back', clients_path %> <h1>New client</h1> <%= render :partial => 'form', :locals => {:btn_text => "Create"} %> <%= link_to 'Back', clients_path %>

DRY , use Partials Partials ("partial views") are fragments of RHTML that can be inserted into a view. They exist to make the view logic simpler. app/views/clients/edit.html.erb app/views/clients/new.html.erb <h1>Editing client</h1> <%= render :partial => 'form', :locals => {:btn_text => "Update"} %> <%= link_to 'Show', @client %> | <%= link_to 'Back', clients_path %> <h1>New client</h1> <%= render :partial => 'form', :locals => {:btn_text => "Create"} %> <%= link_to 'Back', clients_path %> app/views/clients/_form.html.erb <% form_for(@client) do |f| %> <%= f.error_messages %> <p> <%= f.label :name %><br /> <%= f.text_field :name %> </p> <p> <%= f.label :age %><br /> <%= f.text_field :age %> </p> <p> <%= f.label :comments %><br /> <%= f.text_area :comments %> </p> <p> <%= f.submit btn_text %> </p> <% end %>

Rails comes bundled with helpers capable of automating tasks such as creating form fields, using Ajax, embedding assets such as JavaScript and CSS files, etc. Occasionally you’ll be looking for a helper that isn’t bundled with the documentation, one capable of abstracting a task you’ll be using repeatedly in a view. You can do your own Helper. text_field ( :post , :title , :size => 20) ‏ <input type="text" id="post_title" name="post[title]" size="20" value="#{@post.title}" /> hidden_field ( :signup , :pass_confirm ) ‏ <input type="hidden" id="signup_pass_confirm" name="signup[pass_confirm]" value="#{@signup.pass_confirm}" /> image_tag ("icon") <img src="/images/icon" alt="Icon" /> app/helpers/students_helper.rb def result_img_tag ( student ) ‏ student.result < 4 ? image_tag ("red.png") : image_tag ("green.png") ‏ end <table> <% for student in @students %> <tr> <td><%=h student.name %></td> <td><%=h student.age %></td> <td><%= result_img_tag(student) %></td> </tr> <% end %> </table>

Database agnosticism Rails supports a wide array of databases, including all the common production database platforms, MySQL, SQL Server, DB2, Oracle, SQLite, etc.

It's Productive!

http://developer.apple.com/tools/rubyonrails.html “ in a world where being the first to market and keeping customers happy adds up to increased revenues for you.”

RIA (Rich Internet Applications) ‏ and Web 2.0

Create interactive interfaces Rails include: RJS (Rails JavaScript Templates) ‏

No JavaScript Programming necessary Say it in Ruby

class ClientsController < ApplicationController ... # GET /clients/1 # GET /clients/1.xml d e f show @client = Client. find (params[ :id ]) ‏ respond_to do |format| format.html # render show.html.erb format.js # render show.js.rjs format.xml { render :xml => @client } end end ... end Ajax call In the RJS file you can express everything in Ruby code: page.replace_html 'elementId' , 'Replacement text' page.remove 'elementId' page.insert_html :top , 'myList' , '<li>New list element<li>' page.visual_effect :fade , 'elementId' , :duration => 0.5 page[ :someform ].reset page[ :cart ].update render( :partial => 'cart' ) ‏ page[ :list ].reload #render list element with partial with the same name page[ :product ].set_style :backgroundColor => '#f00' page.delay( 5 .seconds) do page[ :something ].visualEffect :puff end page << “(3).times( function(){ alert('hi!')});” # If you 'have to' use Javascript page.draggable :product page.drop_receiving :cart , :url => { :action => 'do_something' }

ReST (Representational State Transfer) ‏ config/routes.rb map.resource :clients app/controllers/clients_controller.rb class ClientsController < ActionController::Base def index respond_to do |format| format.html format.xml { render :xml => @clients } end end def new ... end def create ... end def edit ... end def update ... end def destroy ... end end The core abstraction in REST is a remote resource instead of a remote procedure call. Uses TCP/IP naming standards to name resources on the Web Queries and manipulates those resources with HTTP Uses standard text-based message formats like XML or HTML to structure data

TDD – T est D riven D evelopment - If you write tests before you write your code, you end up writing better code. - Forces you to think before you code. - Code becomes is more focused and clear. Write Tests Write code until tests pass Try optimizing the code

BDD – B ehaviour D riven D evelopment - Less about writing tests, and more about writing specifications . - Terminology focused on the behavioural aspects of the system rather than testing. - “Getting the words right”, this focus not only helps you and other developers understand your application, but can be used to show your client that the application is meeting their needs. - The business, developers, testers, analysts and managers are not only on the same page but using the same words. - Developers gain confidence in the systems they build when the behaviour of that system is confirmed. “ Enable better TDD, by focusing on behavior rather then testing” Dan North (behaviour-driven.org) ‏ RSpec is a BDD framework for Ruby . It provides two frameworks for specify how your Ruby application should behave: - a Story Framework for describing behaviour at the application level - a Spec Framework for describing behaviour at the object level

Capistrano - A great tool for deploying your applications. - It's not just a deploy tool, It lets you to execute commands on multiple remote machines in parallel. - Also lets you group your servers by role and specify tasks that should only be executed for certain roles. - Easy to extend. Capistrano is written in the Ruby programming language, and may be extended easily by writing additional Ruby modules. - Interfaces with Git and Subversion . - Is the tool of choice for many Rails developers for automating deployment.

Version Control

Built-in Database Schema Version Control 20080801031822_create_user.rb Migration Files:

User id email Built-in Database Schema Version Control 20080801031822_create_user.rb rake db:migrate Migration Files:

User id email Built-in Database Schema Version Control 20080801031822_create_user.rb rake db:migrate 20080801122231_add_names_column.rb Migration Files:

User id email Built-in Database Schema Version Control User id first_name last_name email 20080801031822_create_user.rb rake db:migrate 20080801122231_add_names_column.rb Migration Files:

User id email Built-in Database Schema Version Control User id first_name last_name email 20080801031822_create_user.rb rake db:migrate 20080801122231_add_names_column.rb Migration Files: 20080801442312_combine_name_columns.rb

User id email Built-in Database Schema Version Control User id first_name last_name email 20080801031822_create_user.rb rake db:migrate 20080801122231_add_names_column.rb Migration Files: 20080801442312_combine_name_columns.rb User id name email

User id email Built-in Database Schema Version Control User id first_name last_name email 20080801031822_create_user.rb rake db:migrate 20080801122231_add_names_column.rb Migration Files: 20080801442312_combine_name_columns.rb User id name email 20080801502802_rename_fullname.rb

User id email Built-in Database Schema Version Control User id first_name last_name email 20080801031822_create_user.rb rake db:migrate 20080801122231_add_names_column.rb Migration Files: 20080801442312_combine_name_columns.rb User id name email 20080801502802_rename_fullname.rb User id fullname email

User id email Built-in Database Schema Version Control User id first_name last_name email User id name email User id fullname email 20080801031822_create_user.rb rake db:migrate rake db:migrate:down 20080801122231_add_names_column.rb 20080801442312_combine_name_columns.rb 20080801502802_rename_fullname.rb Migration Files:

Most popular choices for Code Version Control and Tracking tool : Centralized Repository: Subversion + Track Distributed Repository: Git + Lighthouse

http://subversion.tigris.org/ http://trac.edgewall.org

http://git.or.cz/ http://lighthouseapp.com

Comparison of same web application in Java and Rails : The Java app's configuration alone was nearly the size of the entire Rails codebase Rails application was significantly (15%-30%) faster ! Source: http://www.theserverside.com/news/thread.tss?thread_id=33120 Some Numbers

Projects using Rails

http://www.yellowpages.com/

http://twitter.com/

http://www.37signals.com/

http://www.43things.com/

http://www.facebook.com/apps/application.php?id=7019261521

Can Rails Scale? Absolutely!

23 million unique visitors / month 2 million searches / day More than 48 million requests / day More than 1500 requests / sec Source: http://assets.en.oreilly.com/1/event/6/Surviving%20the%20Big%20Rewrite_%20Moving%20YELLOWPAGES_COM%20to%20Rails%20Presentation.pdf YellowPages.com

10th most popular application on Facebook. Nearly 600,000 active users. Half a million unique visitors a day and growing fast. 300 million page views a month. 300% monthly growth rate, but that is plateauing. 2.1 million unique visitors in the past month 200 requests per second. 5TB of bandwidth per month. Source: http://highscalability.com/friends-sale-architecture-300-million-page-view-month-facebook-ror-app Friends for Sale (Facebook app) ‏

Resources

Just Ruby and Ruby on Rails

Screencasts - http://peepcode.com

Free Screencasts - http://railscast.com

Screencasts, podcasts and tutorials - http://learningrails.com

Api documentation - http://api.rubyonrails.org/ and http://apidock.com/

http://gabrey.blogspot.com	57
http://www.slideshare.net	6
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Ruby On Rails Introduction

by gbrey on Mar 02, 2010

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Ruby On Rails Introduction — Presentation Transcript