Rails Email Background Tasks Modules

Rails Summer of Code
Week 6

Richard Schneeman - @ThinkBohemian

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


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


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)


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


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


How Does RoR Send
Email?
• Low Volume Mail Server Operating System

• use Gmail
Your
Computer MTA

• High Volume
Postﬁx
SMTP
(Sends Emails)
d

• use a re-mailer Their
Computer Courier
IMAP/POP

• Build your own


How Does RoR Send
Email?
• ActionMailer

• Mail Gem

rails generate mailer Notiﬁer

/app/mailers/notiﬁer.rb


Email With Rails

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

Email With Rails

• Default Mailer Settings

• In-Line Attachments

• mail( ) method


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


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


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?


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

Background Task
• rake tasks
• organize code in “lib/tasks”
• run with:
rake <command> RAILS_ENV=<environment>


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

rake cleanup:old_tickets


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


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


Cron
• Awesome, but verbose

• Use Whenever gem instead


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


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

sudo gem install god


Background Processes
• More Options
• Workling/Starling
• Backgroundrb


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


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

puppy = Dog.new
puppy.drug_test
>> Passed

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

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

Modules (ruby)
module AntiCheating
def self.cleanup( level)
...
end
end

AntiCheating.cleanup(10)
>>Very Clean


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

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

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

Dog.sniff


Modules (ruby)
• Extra Credit:
• class << self
class << self def self.cleanup( level)
include AntiCheating ...
end end
end end

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

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

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


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


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


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


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


Observers
• Add callback functionality without polluting the
model

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

i18n & L10n

Source: @mattt

language conﬁguration
Source: @mattt

Source: @mattt


Multiple Language Files
fr.yml

ja.yml

Source: @mattt

It Worked!

Source: @mattt

What about L10n


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


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