This series introduces students to ruby on rails 3 through the book "Agile Web Development with Rails" with accompanying lecture videos found at http://www.thinkbohemian.com/tag/rails-summer-of-code/

1. Rails Summer of Code
Week 2
Richard Schneeman - @ThinkBohemian

2. Rails - Week 2
• Ruby
• Hashes
• Classes
• Macros
• Methods
• Instances
• Methods
Richard Schneeman - @ThinkBohemian

3. Ruby
• Hashes - (Like a Struct)
• Key - Value Pairs - Different DataTypes Ok
hash = {:a => 100, :b => “hello”}
>> hash[:a]
=> 100
>> hash[:b]
=> hello
>> hash.keys
=> [:b, :a]
Richard Schneeman - @ThinkBohemian

4. Ruby
• Hashes in method parameters
• options (a hash) is optional parameter
def myMethod(variable, options = {})
puts variable
options.keys.each do |key|
puts options[key]
end
end
>> myMethod(“Hi”)
=> Hi
>> myMethod(“Hi”, :a => “hello” , “there”)
=> Hi
Hello
There
Richard Schneeman - @ThinkBohemian

5. Hashes in Rails
• Used heavily
• options (a hash) is optional parameter
Rails API: (ActionView::Helpers::FormHelper) text_area
Richard Schneeman - @ThinkBohemian

6. Hashes in Rails
• Used heavily
• options (a hash) is optional parameter
Rails API: (ActionView::Helpers::FormHelper) text_area
Richard Schneeman - @ThinkBohemian

7. Ruby
• Objects don’t have attributes
• Need getter & setter methods
class MyClass
def myAttribute=(value)
@myAttribute = value
end
def myAttribute
@myAttribute
end
end
>> object = MyClass.new
>> object.myAttribute = “foo”
>> object.myAttribute
=> “foo”
Richard Schneeman - @ThinkBohemian

8. Ruby
• Ruby gives us Class Macros !!
• Example: attr_accessor
class MyClass
attr_accessor :myAttribute
end
>> object = MyClass.new
>> object.myAttribute = “foo”
>> object.myAttribute
=> “foo”
Richard Schneeman - @ThinkBohemian

9. Ruby
• Class Methods
• (methods that can be run on the class)
class My_class
def myInstanceMethod(value)
puts value
end
def self.myClassMethod(value)
puts value
end
end
My_class.myClassMethod("foo")
=> "foo"
Richard Schneeman - @ThinkBohemian

10. Ruby
• Class Methods
• (methods that can be run on the class)
class My_class
def myInstanceMethod(value)
puts value
end
def self.myClassMethod(value)
puts value
end
end
My_class.myClassMethod("foo")
=> "foo"
Richard Schneeman - @ThinkBohemian

11. Ruby
• Instance Methods
class My_class
def myInstanceMethod(value)
puts value
end
def self.myClassMethod(value)
puts value
end
end
>> myInstance = My_class.new
>> myInstance.myInstanceMethod("foo")
=> “foo”
>> myInstance.myClassMethod(“bar”)
=> undefined method ‘myClassMethod’ for #<My_class:0x100124d18>
Richard Schneeman - @ThinkBohemian

12. Ruby
• Instance Methods
class My_class
def myInstanceMethod(value)
puts value
end
def self.myClassMethod(value)
puts value
end
end
>> myInstance = My_class.new
>> myInstance.myInstanceMethod("foo")
=> “foo”
>> myInstance.myClassMethod(“bar”)
=> undefined method ‘myClassMethod’ for #<My_class:0x100124d18>
Richard Schneeman - @ThinkBohemian

13. Ruby
• Instance Methods
class My_class
def myInstanceMethod(value)
puts value
end
def self.myClassMethod(value)
puts value
end
end
>> myInstance = My_class.new
>> myInstance.myInstanceMethod("foo")
=> “foo”
>> myInstance.myClassMethod(“bar”)
=> undefined method ‘myClassMethod’ for #<My_class:0x100124d18>
Richard Schneeman - @ThinkBohemian

14. Ruby
• Class Methods class Dog
• Have self
def self.find(name)
...
end
• Instance Methods
def wag_tail(frequency)
...
• Don’t (Have self)
end
end
Richard Schneeman - @ThinkBohemian

15. Ruby
• Class Methods class Dog
• Have self
def self.find(name)
...
end
• Instance Methods
def wag_tail(frequency)
...
• Don’t (Have self)
end
end
Richard Schneeman - @ThinkBohemian

16. Ruby
• attr_accessor is a Class method
attr_accessor :myAttribute
Can be defined as:
def self.attr_accessor(value)
...
end
cool !
Richard Schneeman - @ThinkBohemian

17. Rails - Week 2
• Code Generation
• Migrations
• Scaffolding
• Validation
• Testing (Rspec AutoTest)
Richard Schneeman - @ThinkBohemian

18. Scaffolding
• Generate Model, View, and Controller & Migration
>> rails generate scaffold Post name:string title:string content:text
• Generates “One Size Fits All” code
• app/models/post.rb
• app/controllers/posts_controller.rb
• app/views/posts/ {index, show, new, create, destroy}
• Modify to suite needs (convention over configuration)
Richard Schneeman - @ThinkBohemian

19. Migrations
• Create your data structure in your Database
• Set a database’s schema
migrate/create_post.rb
class CreatePost < ActiveRecord::Migration
def self.up
create_table :post do |t|
t.string :name
t.string :title
t.text :content
end
SystemSetting.create :name => "notice", :label => "Use notice?", :value => 1
end
def self.down
drop_table :posts
end
end
Richard Schneeman - @ThinkBohemian

20. Migrations
• Get your data structure into your database
>> rake db:migrate
• Runs all “Up” migrations
def self.up
create_table :post do |t|
t.string :name
t.string :title
t.text :content
end
end
Richard Schneeman - @ThinkBohemian

21. Migrations
• Creates a Table named post def self.up
create_table :post do |t|
• Adds Columns t.string
t.string
:name
:title
•
t.text :content
Name, Title, Content end
end
• created_at & updated_at
added automatically
Richard Schneeman - @ThinkBohemian

22. Migrations
• Creates a Table named post def self.up
create_table :post do |t|
• Adds Columns t.string
t.string
:name
:title
•
t.text :content
Name, Title, Content end
end
• created_at & updated_at
added automatically
Richard Schneeman - @ThinkBohemian

23. Migrations
• Active Record maps ruby objects to database
• Post.title
Active Record is Rail’s ORM
def self.up
create_table :post do |t|
t.string :name
t.string :title
t.text :content
end
end
Richard Schneeman - @ThinkBohemian

24. Migrations
• Active Record maps ruby objects to database
• Post.title
Active Record is Rail’s ORM
def self.up
create_table :post do |t|
t.string :name
t.string :title
t.text :content
end
end
Richard Schneeman - @ThinkBohemian

25. Migrations
• Active Record maps ruby objects to database
• Post.title
Active Record is Rail’s ORM
def self.up
create_table :post do |t|
t.string :name
t.string :title
t.text :content
end
end
Richard Schneeman - @ThinkBohemian

26. Migrations
• Active Record maps ruby objects to database
• Post.title
Active Record is Rail’s ORM
def self.up
create_table :post do |t|
t.string :name
t.string :title
t.text :content
end
end
Richard Schneeman - @ThinkBohemian

27. Migrations
• Active Record maps ruby objects to database
• Post.title
Active Record is Rail’s ORM
def self.up
create_table :post do |t|
t.string :name
t.string :title
t.text :content
end
end
Richard Schneeman - @ThinkBohemian

28. Migrations
• Made a mistake? Issue a database Ctrl + Z !
>> rake db:rollback
• Runs last “down” migration
def self.down
drop_table :system_settings
end
Richard Schneeman - @ThinkBohemian

29. Scaffolding
• Generate Model, View, and Controller
>> scaffold Post name:string title:string content:text
• models/post.rb
• controllers/posts_controller.rb
• views/post/{ index.html, show.html, new.html, create.html }
Richard Schneeman - @ThinkBohemian

30. Rails - Validations
• Check your parameters before save
• Provided by ActiveModel
• Utilized by ActiveRecord
class Person < ActiveRecord::Base
validates :title, :presence => true, :title => true
end
bob = Person.create(:title => nil)
>> bob.valid?
=> false
>> bob.save
=> false
Richard Schneeman - @ThinkBohemian

31. Rails - Validations
Can use ActiveModel without Rails
class Person
include ActiveModel::Validations
attr_accessor :title
validates :title, :presence => true, :title => true
end
bob = Person.create(:title => nil)
>> bob.valid?
=> false
>> bob.save
=> false
Richard Schneeman - @ThinkBohemian

32. Rails - Validations
• Use Rail’s built in Validations
# :acceptance => Boolean.
# :confirmation => Boolean.
# :exclusion => { :in => Ennumerable }.
# :inclusion => { :in => Ennumerable }.
# :format => { :with => Regexp, :on => :create }.
# :length => { :maximum => Fixnum }.
# :numericality => Boolean.
# :presence => Boolean.
# :uniqueness => Boolean.
• Write your Own Validations
class User < ActiveRecord::Base
validate :my_custom_validation
private
def my_custom_validation
self.errors.add(:password, "Custom Message") unless self.property.present?
end
end
Richard Schneeman - @ThinkBohemian

33. Testing
• Test your code (or wish you did)
• Makes upgrading and refactoring easier
• Different Environments
• production - live on the web
• development - on your local computer
• test - local clean environment
Richard Schneeman - @ThinkBohemian

34. Testing
• Unit Tests
• Test individual methods against known inputs
• Integration Tests
• Test Multiple Controllers
• Functional Tests
• Test full stack M- V-C
Richard Schneeman - @ThinkBohemian

35. Unit Testing
• ActiveSupport::TestCase
• Provides assert statements
• assert true
• assert (variable)
• assert_same( obj1, obj2 )
• many more
Richard Schneeman - @ThinkBohemian

36. Unit Testing
• Run Unit Tests using:
>> rake test:units RAILS_ENV=test
Richard Schneeman - @ThinkBohemian

37. Unit Testing
• Run Tests automatically the background
• ZenTest
• sudo gem install ZenTest
• Run:
>> autotest
Richard Schneeman - @ThinkBohemian

38. Questions?
Richard Schneeman - @ThinkBohemian