gistfile1.txt

1.9.3-p125 :044 > accepts = "en,en-US;0.8,es;0.2"
 => "en,en-US;0.8,es;0.2" 
1.9.3-p125 :045 > accepts.scan(/([\w-]{2,})/).map(&:first).map(&:to_sym)
 => [:en, :"en-US", :es] 
1.9.3-p125 :046 > accepts.downcase.scan(/([\w-]{2,})/).map(&:first)
 => ["en", "en-us", "es"] 

####

symbols = Symbol.all_symbols
# => [...]
I18n.locale = "garbage_from_a_user"
# => "garbage_from_a_user" 
I18n.locale
# => :garbage_from_a_user 
Symbol.all_symbols - symbols
# => [:garbage_from_a_user] 

#####

class ApplicationController < ActionController::Base
  before_filter :set_locale
  
private
  
  def set_locale
    I18n.locale = params[:locale]
  end
end

#####

class ApplicationController < ActionController::Base
  before_filter :set_locale
  
private
  
  def set_locale
    if params[:locale]
      locale = params[:locale].downcase
      I18n.locale = locale if locale_available?(locale)
    end
  end

  def locale_available?(locale)
    I18n.available_locales.map(&:to_s).include?(locale)
  end
end

#####

class ApplicationController < ActionController::Base
  before_filter :set_locale

  def default_url_options(options = {})
    { :locale => I18n.locale }.merge(options)
  end

  #...
end

#####

class ApplicationController < ActionController::Base
  before_filter :set_locale

  def default_url_options(options = {})
    { :locale => I18n.locale }.merge(options)
  end
  
private
  
  def set_locale
    if params[:locale]
      locale = params[:locale].downcase
      I18n.locale = locale if locale_available?(locale)
    end
  end

  def locale_available?(locale)
    I18n.available_locales.map(&:to_s).include?(locale)
  end
end

#####

class ApplicationController < ActionController::Base
  before_filter :set_locale

private
  
  def store_locale
    session["locale"] = I18n.locale
  end

  def locale_available?(locale)
    I18n.available_locales.map(&:to_s).include?(locale)
  end
end

#####

## Setting the Locale

session[:locale] = I18n.locale

## Fetching the Locale

I18n.locale = session[:locale]

## Different Users

session["locale_for_#{current_user.to_param}"] = I18n.locale
I18n.locale = session["locale_for_#{current_user.to_param}"]

## User Preferences

Image: preferences?

## Store in the DB

rails generate migration add_locale_to_users locale:string

## ApplicationController

before_filter :set_locale

private

  def set_locale
    I18n.locale = current_user.locale || I18n.default_locale
  end

## Composite Strategy

Image: quilt

## Composite Code

class ApplicationController < ActionController::Base
  include LocaleController
end

module LocaleController
  def self.included(controller)
    controller.class_eval do
      before_filter :set_locale

      def default_url_options(options = {})
        { :locale => I18n.locale }.merge(options)
      end
  
      def set_locale
        LocaleSetter.set_by(:user => current_user,
                            :params => params,
                            :session => session,
                            :http => request.env['HTTP_ACCEPT_LANGUAGE'])
      end
    end
  end
end

module LocaleSetter

  LOOKUP_CHAIN = [:params, :user, :session, :http, :default]

  # def self.set_by(inputs)
  #   by_params(inputs[:params]) ||
  #     by_user(inputs[:user])   ||
  #     by_session(inputs[:session], inputs[:user]) ||
  #     by_http(inputs[:http])   ||
  #     I18n.default_locale
  # end

  def self.set_by(inputs)
    LOOKUP_CHAIN.detect do |lookup|
      send("by_#{lookup}", inputs[lookup]) if params[lookup]
    end
  end

  def self.by_params(params)
    locale = params[:locale].downcase
    locale if locale_available?(locale)
  end

  def self.by_session(session)
    session[:locale]
  end

  def self.by_user(user)
    user.locale
  end

  def self.by_http(accepts)
    (accept_list(accepts) & I18n.available_locales).first

  end

  def self.locale_available?(locale)
    I18n.available_locales.map(&:to_s).include?(locale)
  end

private

  def self.accept_list(accepts)

    accepts.downcase.scan(/([\w-]{2,})/).map{|l| l.first.to_sym}

  end
  
end

#### Using Lookup Files

Image: Dictionary

#### Normal YAML

en:
  article:
    deleted: "Article has been deleted."
    error: "Article failed to save."
    created: "Article created successfully."
    new: "New Article"
    update: "Save Changes"
    create: "Save Article"
  comment:
    created: "Comment posted, you're internet famous."
    spam: "Burn your own face off, spammer."
    create: "Post Comment"
    status:
      moderation: "Comment is pending moderation."
      approved: "Comment approved."


#### t and I18n.t

t 'article.deleted'
I18n.t 'comment.created'
t 'comment.status.approved'

#### Interpolation

en:
  generic:
    deleted: "%{subject} has been deleted."
    error: "%{subject} failed to save."

t 'generic.deleted', :subject => "Comment"

'(Ugh, what about "Comment"?)'

en:
  models:
    comment: "Comment"
    article: "Article"
  generic:
    deleted: "%{subject} has been deleted."
    error: "%{subject} failed to save."

t 'generic.deleted', :subject => t('models.comment')

'But wait...'

### Automatic Lookups with ActiveRecord

Image: Robot, assistant, file cabinet

### The Magic!

a = Article.new(:body => "boo")
a.save
a.errors.first.inspect
a.errors.first.last

  # In Translation File...

en:
  activerecord:
    errors:
      models:
        article:
          attributes:
            title:
              blank: "You need a title!"

### Validation Key

Insert the table from the RailsGuide

### Lookup Path & Priority

activerecord.errors.models.[model_name].attributes.[attribute_name]
activerecord.errors.models.[model_name]
activerecord.errors.messages
errors.attributes.[attribute_name]
errors.messages

### Validation Message Lookup

en:
  activerecord:
    errors:
      models:
        article:
          attributes:
            title:
              blank: "You need a title!"

### In the View Layer

  <%= errors_for(@article) %>

  module ApplicationHelper
    def errors_for(subject)
      if subject.errors
        render(:partial => 'common/errors', 
               :subject => subject.errors)
      end
    end
  end

  <%= if errors.any? %>
    <div class='errors'>
      <ul>
        <% errors.each do |e|
          <li><%= e.last %></li>
        <% end %>
      </ul>
    </div>
  <% end %>

### Attribute & Model Names

en:
  activerecord:
    attributes:
      article:
        title: "Title"
      comment:
        body: "Your comment"

### Applied in the View

  <%= errors_for(@article) %>

  <p>
    <%= f.label :title %>
    <%= f.text_field :title %>
  </p>

Should line 154 set I18n.locale?

def set_locale
        I18n.locale = LocaleSetter.set_by(:user => current_user,
                            :params => params,
                            :session => session,
                            :http => request.env['HTTP_ACCEPT_LANGUAGE'])
end