1. Rapid Web
Application
Development using
Ruby on Rails
●
Sang Shin
●Sun Microsystems, Inc.
●
javapassion.com
1

2. You can try all the demos
yourself!
Join “Ruby, JRuby, Rails”
free online course!
www.javapassion.com/rubyonrails

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
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7. Rails Basics

8. “Ruby on Rails” MVC
source: http://www.ilug-cal.org 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
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11. Demo:
Building “Hello World”
Rails Application Step by Step.
http://www.javapassion.com/handsonlabs/rails_basics/#Exercise_1
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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
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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
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14. Demo:
How to create an input form.
http://www.javapassion.com/handsonlabs/rails_basics/#Exercise_4
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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
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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
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18. Demo:
Creating a Rails Application
using Scaffolding
http://www.javapassion.com/handsonlabs/rails_scaffold/#Exercise_1
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19. Key Learning Points
• How to perform scaffolding using Generator
• What action methods are created through
scaffolding
• What templates are created through scaffolding
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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
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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)
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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
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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
http://www.javapassion.com/handsonlabs/rails_scaffold/#Exercise_2
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
http://www.javapassion.com/handsonlabs/rails_scaffold/#2.4
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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
http://www.javapassion.com/handsonlabs/rails_activerecord/
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
http://www.javapassion.com/handsonlabs/rails_deploy/#Exercise_1
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.
●
javapassion.com
49