UT on Rails3 2010- Week 2

Rails Summer of Code
Week 2

Richard Schneeman - @ThinkBohemian

Rails - Week 2
• Ruby
• Hashes
• Classes
• Macros
• Methods
• Instances
• Methods

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]


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

Hashes in Rails
• Used heavily
• options (a hash) is optional parameter

Rails API: (ActionView::Helpers::FormHelper) text_area

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”


Ruby
• Ruby gives us Class Macros !!
• Example: attr_accessor
class MyClass
attr_accessor :myAttribute
end

>> object = MyClass.new
>> object.myAttribute = “foo”
>> object.myAttribute
=> “foo”


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"


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>


Ruby
• Class Methods class Dog

• Have self
def self.ﬁnd(name)

...
end

• Instance Methods
def wag_tail(frequency)
...
• Don’t (Have self)
end

end


Ruby
• attr_accessor is a Class method
attr_accessor :myAttribute

Can be deﬁned as:

def self.attr_accessor(value)
...
end

cool !


Rails - Week 2
• Code Generation
• Migrations
• Scaffolding
• Validation
• Testing (Rspec AutoTest)


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)

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


Migrations
• Get your data structure into your database

>> rake db:migrate

• Runs all “Up” migrations

def self.up
t.string :name
t.string :title
t.text :content
end
end


Migrations
• Creates a Table named post def self.up
• Adds Columns t.string
t.string
:name
:title

•
t.text :content
Name, Title, Content end
end

• created_at & updated_at
added automatically


Migrations
• Active Record maps ruby objects to database

• Post.title

Active Record is Rail’s ORM

def self.up
t.string :name
t.string :title
t.text :content
end
end


Migrations
• Made a mistake? Issue a database Ctrl + Z !

>> rake db:rollback

• Runs last “down” migration

def self.down
drop_table :system_settings
end


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 }


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


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


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


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

Testing
• Unit Tests
• Test individual methods against known inputs
• Integration Tests
• Test Multiple Controllers
• Functional Tests
• Test full stack M- V-C

Unit Testing
• ActiveSupport::TestCase
• Provides assert statements
• assert true
• assert (variable)
• assert_same( obj1, obj2 )
• many more

Unit Testing
• Run Unit Tests using:
>> rake test:units RAILS_ENV=test


Unit Testing
• Run Tests automatically the background
• ZenTest
• sudo gem install ZenTest
• Run:
>> autotest


Questions?


UT on Rails3 2010- Week 2

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