Rails 3 Beginner to Builder 2011 Week 6

Beginner to Builder
Week 6

June, 2011
Wednesday, July 20, 2011

Rails - Week 6
• Email in Rails
• Background Tasks
• modules
• Observers & Callbacks
• Internationalization & Localization
• I18n & L10n

@Schneems

Email in Rails
• What is Email?
• Why Use Email?
• How does Rails use email?

@Schneems

What is Email
• Communications medium deﬁned by RFC standards
✦ RFC = Request for Comments
✦ Comprised of Header & Body
✦
Header (to, from, reply-to, content-type, subject, cc, etc.)
✦
Body (message and attachments)

@Schneems

Email- Content Types
• Deﬁnes How the Mail User Agent (MUA) Interprets Body
✦ Text/HTML
✦ Text/Plain
✦ Multipart/Related (Example: Inline Pictures)
✦ Multipart/Alternative
✦
Send Text/HTML with Text/Plain as backup
✦
Add Attachments

@Schneems

Why use Email with
Rails?
• Status Updates ( Twitter, Facebook, Etc. )

• Direct to Consumer Marketing source

• Added functionality (lost passwords, etc.)

• Send documents

• Everyone has it, and

• Everyone can use it

@Schneems

How Does RoR Send
Email? Mail Server

• Low Volume
Operating System
Your
Computer MTA

• use Gmail Postﬁx
SMTP

• High Volume
(Sends d
Emails)

Their
Computer Courier

• use a re-mailer IMAP/POP

• Build your own

@Schneems

How Does RoR Send
• ActionMailer

• Mail Gem

rails generate mailer Notifier

/app/mailers/notiﬁer.rb

@Schneems

Email With Rails

Notiﬁer.signup_notiﬁcation(“foo@example.com”).deliver
@Schneems

Email With Rails
• Default Mailer
Settings

• In-Line Attachments

• mail( ) method

Notiﬁer.signup_notiﬁcation(“foo@example.com”).deliver
@Schneems

Email With Rails
✦ Using Gmail
conﬁg/environments/development.rb
✦ Use Port 587
✦ Gmail will throttle large
number of email requests
✦ Close to real life conditions
✦ Relatively Easy
✦ Don’t use with automated
testing

Notifier.signup_notification(“foo@example.com”).deliver
@Schneems

Email re-cap
✦ Receiving Email much harder
✦ Also less common
✦ Test your Mailer using an Interceptor
✦ use a re-mailer in production
✦ real life application: http://whyspam.me
✦ No longer running

@Schneems

Background Tasks
• What is a background task?
• Why use one?
• Where do i put my task in rails?
• How do i keep my task alive?

@Schneems

Background Task
• What is a background task?
• Any server process not initiated by http
request
• Commonly run for long periods of time
• Do not block or stop your application
• Clean up server, or application
• Generate reports
• Much more
@Schneems

Background Task
• rake tasks
• organize code in “lib/tasks”
• run with:

rake <command> RAILS_ENV=<environment>

@Schneems

Background Task
• Example
• cleanup.rake
namespace :cleanup do
desc "clean out Tickets over 30 days old"
task :old_tickets => :environment do
tickets = Ticket.find(:all, :conditions => ["created_at < ?",
30.days.ago ], :limit => 5000)
tickets.each do |ticket|
ticket.delete
end
end
end

rake cleanup:old_tickets

@Schneems

Background Task
• What if i don’t want to execute from
command line?
• run task with a automation program
• Cron
• Monit
• God

@Schneems

Cron
• Very reliable unix time scheduler
• Built into the OS
• Executes command line calls
• Smallest interval is 1 minute
• Requires full paths

@Schneems

Monit
• Not installed on OS by default
• Monitors and Executes (cron only executes)
• Extra functionality - Sysadmin emails etc...

@Schneems

God
• Written in ruby
• Very conﬁgurable
• can be memory
intensive in some
applications

sudo gem install god

@Schneems

Background
• More Options
• Workling/Starling
• Backgroundrb
• ResQue

@Schneems

Modules (ruby)
• Add “Mixins” to your code
• Keep code seperate with different namespaces
• put them in your rails project under /lib

@Schneems

Modules (ruby)
• Example Mixin:
• include adds instance methods
module AntiCheating
class Dog
def drug_test
include AntiCheating
...
end
end
end

puppy = Dog.new
puppy.drug_test
>> Passed
@Schneems

Modules (ruby)
• Example Mixin 2:
module AntiCheating
class Dog
def self.cleanup(level)
...
end
end
end

dirtyDog = Dog.new
dirtyDog.cleanup
>> No Method Error

@Schneems

Modules (ruby)
module AntiCheating
...
end
end

AntiCheating.cleanup
>> Very Clean

@Schneems

Modules (ruby)
• extend adds all module methods
class Dog module AntiCheating
extend AntiCheating def self.cleanup(level)
end ...
end
end

dirtyDog = Dog.new
dirtyDog.cleanup(2)
>> “Kinda Clean”

@Schneems

Modules (ruby)
• Extra Credit:
• class << self
class Dog
class Dog
class << self
def self.sniff
def sniff
... == ...
end
end
end
end
end

@Schneems

Modules (ruby)
• Extra Credit:
• class << self
class Dog
module AntiCheating
class << self
...
end
end
end
end

dirtyDog = Dog.new
dirtyDog.cleanup(10)
>> “Really Clean”
@Schneems

Modules (ruby)
• Example Namespace
module FastDogs module SlowDogs
class Dog class Dog
... ...
end end
end end

lassie = FastDogs::Dog.new droopy = SlowDogs::Dog.new

@Schneems

Callbacks and Observers
• Callbacks
• Non-polling event based method
• hooks into lifecycle of Active Record object
• Observers
• Implement trigger behavior for class outside
of the original class

@Schneems

Callbacks
• Polling
• “Are We there Yet”
• Callback
• “I’ll tell you when we’re there”

@Schneems

Callbacks in Rails
save
• Lifecycle Hooks => (-) valid
(1) before_validation
(2) before_validation_on_create
(-) validate
(-) validate_on_create
(3) after_validation
(4) after_validation_on_create
(5) before_save
(6) before_create
(-) create
(7) after_create
(8) after_save

@Schneems

Callbacks in Rails
• Example
• before_destroy
class Topic < ActiveRecord::Base
before_destroy :delete_parents
def delete_parents
self.class.delete_all "parent_id = #{id}"
end
end
end

@Schneems

Observers
• Add callback functionality without polluting the
model

• Will run after every new user instance is created
• Keeps your code clean(er)
@Schneems

i18n & L10n

Source: @mattt
@Schneems

i18n & L10n

Source: @mattt

@Schneems

language conﬁguration
Source: @mattt

Source: @mattt

@Schneems

Multiple Language Files
fr.yml

ja.yml

Source: @mattt
@Schneems

It Worked!

Source: @mattt
@Schneems

What about L10n

@Schneems

Questions?
http://guides.rubyonrails.org
http://stackoverﬂow.com
http://peepcode.com

@Schneems

Rails 3 Beginner to Builder 2011 Week 6

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