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  • 1. Rapid Web Application Development using Ruby on Rails ● Sang Shin ●Sun Microsystems, Inc. ● 1
  • 2. You can try all the demos yourself! Join “Ruby, JRuby, Rails” free online course!
  • 3. Topics • What is and Why Ruby on Rails (Rails)? • Rails Basics • Step by step for building “Hello World” Rails application • ActiveRecord • ActionController • ActionView • Deployment 3
  • 4. What is and Why Ruby on Rails (RoR)?
  • 5. What Is “Ruby on Rails”? • A full-stack MVC web development framework • Written in Ruby • First released in 2004 by David Heinemeier Hansson • Gaining popularity 5
  • 6. “Ruby on Rails” Principles • Convention over configuration > Why punish the common cases? > Encourages standard practices > Everything simpler and smaller • Don’t Repeat Yourself (DRY) > Repetitive code is harmful to adaptability • Agile development environment > No recompile, deploy, restart cycles > Simple tools to generate code quickly > Testing built into the framework 6
  • 7. Rails Basics
  • 8. “Ruby on Rails” MVC source: 8
  • 9. Step By Step Process of Building “Hello World” Rails Application
  • 10. Steps to Follow 1.Create “Ruby on Rails” project > IDE generate necessary directories and files 2.Create and populate database tables 3.Create Models (through Rails Generator) > Migrate database 4.Create Controllers (through Rails Generator) 5.Create Views 6.Set URL Routing > Map URL to controller and action 10
  • 11. Demo: Building “Hello World” Rails Application Step by Step. 11
  • 12. Key Learning Points • How to create a Rails project > Rails application directory structure > Concept of environments - development, test, and production • How to create a database using Rake • How to create and populate tables using Migration • How to create a model using Generator • How to use Rails console 12
  • 13. Key Learning Points • How to create a controller using Generator > How to add actions to a controller • How to create a related view > How a controller and a view are related > How to create instance variables in an action and they are used in a view • How to set up a routing • How to trouble-shoot a problem 13
  • 14. Demo: How to create an input form. 14
  • 15. Key Learning Points • How to use form_tag and text_field helpers to create an input form • How input form fields are accessed in an action method through params 15
  • 16. Scaffolding
  • 17. What is Scaffolding? • Scaffolding is a way to quickly create a CRUD application > Rails framework generates a set of actions for listing, showing, creating, updating, and destroying objects of the class > These standardized actions come with both controller logic and default templates that through introspection already know which fields to display and which input types to use • Supports RESTful view of the a Model 17
  • 18. Demo: Creating a Rails Application using Scaffolding 18
  • 19. Key Learning Points • How to perform scaffolding using Generator • What action methods are created through scaffolding • What templates are created through scaffolding 19
  • 20. ActiveRecord Basics
  • 21. ActiveRecord Basics • Model (from MVC) • Object Relation Mapping library > A table maps to a Ruby class (Model) > A row maps to a Ruby object > Columns map to attributes • Database agnostic • Your model class extends ActiveRecord::Base 21
  • 22. ActiveRecord Class • Your model class extends ActiveRecord::Base class User < ActiveRecord::Base end • You model class contain domain logic class User < ActiveRecord::Base def self.authenticate_safely(user_name, password) find(:first, :conditions => [ "user_name = ? AND password = ?", user_name, password ]) end end 22
  • 23. Naming Conventions • Table names are plural and class names are singular > posts (table), Post (class) > students (table), Student (class) > people (table), Person (class) • Tables contain a column named id 23
  • 24. Find: Examples • find by id Person.find(1) # returns the object for ID = 1 Person.find(1, 2, 6) # returns an array for objects with IDs in (1, 2, 6) • find first Person.find(:first) # returns the first object fetched by SELECT * FROM peop Person.find(:first, :conditions => [ "user_name = ?", user_name]) Person.find(:first, :order => "created_on DESC", :offset => 5) 24
  • 25. Dynamic attribute-based finders • Dynamic attribute-based finders are a cleaner way of getting (and/or creating) objects by simple queries without turning to SQL • They work by appending the name of an attribute to find_by_ or find_all_by_, so you get finders like > Person.find_by_user_name(user_name) > Person.find(:first, :conditions => ["user_name = ?", user_name]) > Person.find_all_by_last_name(last_name) > Person.find(:all, :conditions => ["last_name = ?", last_name]) > Payment.find_by_transaction_id 25
  • 26. ActiveRecord Migration
  • 27. ActiveRecord Migration • Provides version control of database schema > Adding a new field to a table > Removing a field from an existing table > Changing the name of the column > Creating a new table • Each change in schema is represented in pure Ruby code 27
  • 28. Example: Migration • Add a boolean flag to the accounts table and remove it again, if you’re backing out of the migration. class AddSsl < ActiveRecord::Migration def self.up add_column :accounts, :ssl_enabled, :boolean, :default => 1 end def self.down remove_column :accounts, :ssl_enabled end end 28
  • 29. Demo: How to add a field to a table using Migration 29
  • 30. Key Learning Points • How to add a new field to a table using Migration • How to create a migration file using Generator • How to see a log file 30
  • 31. ActiveRecord Validation
  • 32. ActiveRecord::Validations • Validation methods class User < ActiveRecord::Base validates_presence_of :username, :level validates_uniqueness_of :username validates_oak_id :username validates_length_of :username, :maximum => 3, :allow_nil validates_numericality_of :value, :on => :create end 32
  • 33. Validation 33
  • 34. Demo: Validation 34
  • 35. ActiveRecord:: Associations
  • 36. Associations • Associations are a set of macro-like class methods for tying objects together through foreign keys. • They express relationships like "Project has one Project Manager" or "Project belongs to a Portfolio". • Each macro adds a number of methods to the class which are specialized according to the collection or association symbol and the options hash. • Cardinality > One-to-one, One-to-many, Many-to-many 36
  • 37. One-to-many • Use has_many in the base, and belongs_to in the associated model class Manager < ActiveRecord::Base has_many :employees end class Employee < ActiveRecord::Base belongs_to :manager # foreign key - manager_id end 37
  • 38. Demo: Association 38
  • 39. ActionController Basics
  • 40. ActionController • Controller is made up of one or more actions that are executed on request and then either render a template or redirect to another action • An action is defined as a public method on the controller, which will automatically be made accessible to the web- server through Rails Routes • Actions, by default, render a template in the app/views directory corresponding to the name of the controller and action after executing code in the action. 40
  • 41. ActionController • For example, the index action of the GuestBookController would render the template app/views/guestbook/index.erb by default after populating the @entries instance variable. class GuestBookController < ActionController::Base def index @entries = Entry.find(:all) end def sign Entry.create(params[:entry]) redirect_to :action => "index" end end 41
  • 42. Deployment
  • 43. Web Servers • By default, Rails will try to use Mongrel and lighttpd if they are installed, otherwise Rails will use WEBrick, the webserver that ships with Ruby. • Java Server integration > Goldspike > GlassFish V3 43
  • 44. Goldspike • Rails Plugin • Packages Rails application as WAR • WAR contains a servlet that translates data from the servlet request to the Rails dispatcher • Works for any servlet container • rake war:standalone:create 44
  • 45. Demo: Deployment through Goldspike 45
  • 46. JRuby on Rails
  • 47. Why “JRuby on Rails” over “Ruby on Rails”? • Java technology production environments pervasive > Easier to switch framework vs. whole architecture > Lower barrier to entry • Integration with Java technology libraries, legacy services • No need to leave Java technology servers, libraries, reliability • Deployment to Java application servers 47
  • 48. “JRuby on Rails”: Java EE Platform • Pool database connections • Access any Java Naming and Directory Interface™ (J.N.D.I.) API resource • Access any Java EE platform TLA: > Java Persistence API (JPA) > Java Management Extensions (JMX™) > Enterprise JavaBeans™ (EJB™) > Java Message Service (JMS) API > SOAP/WSDL/SOA 48
  • 49. Rapid Web Application Development using Ruby on Rails ● Sang Shin ●Sun Microsystems, Inc. ● 49