What Is New in Ruby on Rails 2.1

How does the new cache store API affect my Rails 2.1 app?

It introduces a unified config.cache_store setting that lets you swap between memory, file, or memcached stores without touching your caching calls.

# config/environments/production.rb
config.cache_store = :mem_cache_store, "cache-01.example.com", "cache-02.example.com"

In practice you keep using Rails.cache.read/write as before, but you gain the ability to scale caching horizontally by pointing to a cluster of memcached nodes.

What are the Action Mailer enhancements in Rails 2.1?

Rails 2.1 adds native support for multipart/alternative emails and file attachments, making rich email composition straightforward.

class UserMailer < ActionMailer::Base
  def welcome(user)
    attachments['welcome.pdf'] = File.read('welcome.pdf')
    mail(to: user.email,
         subject: "Welcome",
         content_type: "multipart/alternative") do |format|
      format.text { render plain: "Welcome, #{user.name}" }
      format.html { render html: "
Welcome, #{user.name}
".html_safe }
    end
  end
end

This matters if your application sends invoices, newsletters, or any email that needs both plain-text and HTML versions.

How do named scopes improve ActiveRecord queries?

Named scopes let you define reusable, chainable query fragments directly on the model.

class Article < ActiveRecord::Base
  named_scope :published, :conditions => { :status => 'published' }
  named_scope :recent,    :order => 'created_at DESC', :limit => 5
end

# usage
Article.published.recent

Most teams use this to keep controller code thin and to share common filters across the codebase.

What routing improvements should I be aware of when upgrading to Rails 2.1?

Named routes now accept optional parameters and resources gain explicit member and collection routes.

• Optional segments: map.connect ':controller/:action/:id.:format' works without :format.
• Member routes: resources :photos do; member { get :preview }; end
• Collection routes: resources :photos do; collection { get :search }; end

Watch out for routes that previously relied on catch-all patterns; they may need to be tightened to avoid ambiguous matches.

Which deprecations and breaking changes require code changes?

The default cache store is now :file_store, so any custom cache initialization that assumed memory store must be updated.

The old script/plugin install command has been removed; use rails plugin install instead.

Deprecated :conditions hash in find calls encourages migration to the newer where syntax.