![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](https://image.slidesharecdn.com/2622358/85/td_mxc_rubyrails_shin-22-320.jpg)
![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](https://image.slidesharecdn.com/2622358/85/td_mxc_rubyrails_shin-24-320.jpg)
![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](https://image.slidesharecdn.com/2622358/85/td_mxc_rubyrails_shin-25-320.jpg)
![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](https://image.slidesharecdn.com/2622358/85/td_mxc_rubyrails_shin-41-320.jpg)
td_mxc_rubyrails_shin
- 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 6
- 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 10
- 11. Demo: Building “Hello World” Rails Application Step by Step. http://www.javapassion.com/handsonlabs/rails_basics/#Exercise_1 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. http://www.javapassion.com/handsonlabs/rails_basics/#Exercise_4 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 http://www.javapassion.com/handsonlabs/rails_scaffold/#Exercise_1 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
- 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
- 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
- 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 34
- 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
- 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