Upgrading to Rails 3

A Shivasubramanian

What’s new in Rails 3?

Merb merges with Rails Major design changes

Clean separation of responsibilities Hooks for customizing Rails behaviour

Not backwards compatible

Default method for dependency management Gemfile & Gemfile.lock Convert plugins to gems

Plugins – deprecated from Rails 3.2 onwards Bundler works in Rails 2.x with code customizations

Stick to Bundler v1.0.x Remove config.gem calls Remove customizations when moving to Rails 3.

Bundler

.rhtml to .erb

The Rails module

Rails default files

config/preinitializer.rb config/application.rb Only 1 file in script/

script/rails – Represents the rails command

All other files removed – arguments to rails Other default files

Some files’ content have changed in Rails 3 Check for any customizations to default files!

Rails commandsRails 2 command Rails 3 equivalent

./script/console rails console

./script/dbconsole rails dbconsole

./script/destroy rails destroy

./script/generate rails generate

./script/plugin rails plugin

./script/server rails server

./script/about rails about

Rails commands...Create a new application

Rails 2.xrails directory_path

Rails 3.xrails new app_name

Rails frameworks

config.frameworks Rails 2

ActionMailer ActionPack ActiveRecord ActiveResource ActiveSupport Railties

Rails frameworks...

config.frameworks Rails 3

ActionMailer ActionPack ActiveRecord ActiveResource ActiveSupport Railties ActionModel

The Rails Application object

Rails::Application config/application.rb Contains all settings global to your app

Move global settings from config/environment.rb

Other settings belong either in config/environment.rb (or) in individual environment files.

The Rails Application object...

The Rails Application object...Impact on config/routes.rb

Rails 2

Rails 3

The Rails Application object...Impact on config/environment.rb

Rails 2

Rails 3

The Rails Application object...Impact on config/environments/*.rb

Rails 2

The Rails Application object...Impact on config/environments/*.rb

Rails 3

Rails concerns

ActiveSupport::Concern Used to add extra functionality to Ruby/Rails

classes.

Rails concerns...How to customize Rails functionality? (old style)

module A#add my methods

end

class SomeRailsClass include Aend

module A# add my methods

end

class SomeRailsClass extend Aend

class SomeRailsClass# add my methods

end

Rails concerns...How to customize Rails functionality? (old style)

module Amodule ClassMethods

# add all class methods hereendmodule InstanceMethods

# add all instance methods hereenddef self.included(base)

base.send :include, InstanceMethodsbase.send :extend, ClassMethods

endend

Rails concerns...How to customize Rails functionality? (old style)

Disadvantages:Not easy to find what customizations have been done

With include, you don’t need InstanceMethods

With extend, you don’t need ClassMethodsHard to find monkeypatching

Rails concerns...How to customize Rails functionality? (new style)

module Aextend ActiveSupport::Concern

module ClassMethods# add my class methods here

end

module InstanceMethods# add my instance methods

hereend

end

Rails concerns...How to customize Rails functionality? (new style)

Advantages:Easy to find what customizations have been done – search for ActiveSupport::Concern

You still have to include the moduleInstanceMethods module no longer a requirement from Rails 3.2