Advanced Internationalization with Rails

Advanced
Internationalization
with Rails

Clinton R. Nixon
Viget Labs

Hola! Qué tal?
Me llamo Clinton R. Nixon.
Soy programador de software.
Vivo en los Estados Unidos.
Mi cuidad es de Durham en Carolina del Norte.
Hablo un poco de español.
Entiendo un poco mas.
Me encanta Ruby y Rails.

The current state of Rails i18n
Key-value lookup
ActiveRecord support
Interpolation
Weak pluralization
Localized formats
Localized views (index.es.html.erb)

Key-value lookup
en:
site_title: The Lost Tourist
add_tourism_office: Add a New Tourism Office
add_city: Add a New City
es:
site_title: El Turista que se Pierde
add_tourism_office: Crear una Nueva Oficina de Turismo
add_city: Crear una Nueva Cuidad

link_to(t(:site_title), root_url)

ActiveRecord support
es:
activerecord:
errors:
messages:
phone_number: "no se puede en blanco a menos que el número de
teléfono de trabajo, número de teléfono móvil, o otro número de teléfono"
models:
business: Negocio
business_plan: Plan de Negocios
business_process: Función Crítica
attributes:
pet:
name: Nombre
species: Especies
special_needs: Este Mascota Tiene Necesidades Especiales Médicas

Interpolation

es:
welcome_to: "Bienvenido a {{city}}!"

t(:welcome_to, :city => @city.name)

Pluralization

es:
city_has_x_tourism_offices:
one: "Hay {{count}} oficina de turismo de {{city}}."
other: "Hay {{count}} oficinas de turismo de {{city}}."

t(:city_has_x_tourism_offices, :city =>
@city.name, :count => @city.tourism_offices.count)

Localized formats
es:
number:
format:
# Sets the separator between the units (e.g. 1.0 / 2.0 == 0.5)
separator: ","
# Delimits thousands (e.g. 1,000,000 is a million)
delimiter: "."
# Number of decimals (1 with a precision of 2 gives: 1.00)
precision: 3

# Used in number_to_currency()
currency:
format:
# %u is the currency unit, %n the number (default: $5.00)
format: "%n %u"
unit: "€"
# These three are to override number.format and are optional
separator: ","
delimiter: "."
precision: 2

Localized views

app/
views/
cities/
show.haml # used by default locale
show.es.haml # used by :es locale

Difﬁculties

File-based key-value lookup is not user-editable.
Model attributes are not translated.
The Rails inﬂector is not multi-lingual.

Plugins to help

Newsdesk Translate
translatable_columns
Globalize2

Model attribute translations
test "returns the value for the correct locale" do
post = Post.create :subject => 'foo'
I18n.locale = 'de'
post.subject = 'bar'
post.save
I18n.locale = 'en'
post = Post.first
assert_equal 'foo', post.subject
I18n.locale = 'de'
assert_equal 'bar', post.subject
end

Other Globalize2 features
Locale fallbacks
I18n.fallbacks[:"es-‐MX"] # => [:"es-‐MX", :es, :"en-‐US", :en]

Custom pluralization
@backend.add_pluralizer :cz, lambda{|c|
c == 1 ? :one : (2..4).include?(c) ? :few : :other
}

Metadata
rails = I18n.t :rails # if no translation can be found:
rails.locale # => :en
rails.requested_locale # => :es
rails.fallback? # => true
rails.options # returns the options passed to #t
rails.plural_key # returns the plural_key (e.g. :one, :other)
rails.original # returns the original translation

Translating models

Globalize2 and translatable_models
work well for this.

How to start building a backend
The easiest way is to extend
I18n::Backend::Simple.
Key methods are:
init_translations (protected)
store_translations
translate
localize
available_locales

Example: DB-backed backend
class SnippetBackend < I18n::Backend::Simple
# These are the only supported locales
LOCALES = [:en, :es]

protected

def init_translations
load_translations(*I18n.load_path.flatten)
load_translations_from_database
@initialized = true
end
# ...
end

Storing the translations
class Snippet < ActiveRecord::Base
validates_presence_of :name, :en_text, :es_text
validates_uniqueness_of :name
validate :name_must_not_be_subset_of_other_name

private
def name_must_not_be_subset_of_other_name
if self.name =~ /./
snippets = Snippet.find(:all,
:conditions => ['name LIKE ?', "#{self.name}%"])
snippets.reject! { |s| s.id == self.id } unless self.new_record?

unless snippets.empty?
errors.add(:name,
"must not be a subset of another snippet name")
end
end
end
end

Loading translations from DB
def load_translations_from_database
data = { }
LOCALES.each { |locale| data[locale] = {} }

Snippet.all.each do |snippet|
path = snippet.name.split(".")
key = path.pop
current = {}
LOCALES.each { |locale| current[locale] = data[locale] }

path.each do |group|
LOCALES.each do |locale|
current[locale][group] ||= {}
current[locale] = current[locale][group]
end
end

LOCALES.each { |locale|
current[locale][key] = snippet.read_attribute("#{locale}_text") }
end
data.each { |locale, d| merge_translations(locale, d) }
end

Example: a bad idea
module Traductor
class GoogleBackend <
I18n::Backend::Simple
def translate(locale, key, options =
{})
if locale.to_s == 'en'
key
else
Translate.t(key, 'en', locale.to_s)
end
end
end

Translation data format
{:en => {
"pets" => { "canine" => "dog", "feline" => "cat" },
"greeting" => "Hello!",
"farewell" => "Goodbye!" },
:es => {
"pets" => { "canine" => "perro", "feline" =>
"gato" },
"greeting" => "¡Hola!",
"farewell" => "¡Hasta luego!" } }

One could override merge_translations if you needed to
bring in data in another format.

Improving inﬂections

Let’s make the Rails inﬂector multilingual!
This will be incredibly invasive, full of monkey-
patching, and quite dangerous.

Why?

Generated forms: Formtastic, Typus
%h2= City.human_name.pluralize

Black magic
module ActiveSupport::Inflector
def inflections(locale = nil)
locale ||= I18n.locale
locale_class = ActiveSupport::Inflector.const_get(
"Inflections_#{locale}") rescue nil

if locale_class.nil?
ActiveSupport::Inflector.module_eval %{
class ActiveSupport::Inflector::Inflections_#{locale} <
ActiveSupport::Inflector::Inflections
end
}
locale_class = ActiveSupport::Inflector.const_get(
"Inflections_#{locale}")
end

block_given? ? yield locale_class.instance : locale_class.instance
end

Success!
ActiveSupport::Inflector.inflections(:es) do |inflect|
inflect.plural /$/, 's'
inflect.plural /([^aeioué])$/, '1es'
inflect.plural /([aeiou]s)$/, '1'
inflect.plural /z$/, 'ces'
inflect.plural /á([sn])$/, 'a1es'
inflect.plural /í([sn])$/, 'i1es'
inflect.plural /ó([sn])$/, 'o1es'
inflect.plural /ú([sn])$/, 'u1es'
inflect.singular /s$/, ''
inflect.singular /es$/, ''
inflect.irregular('papá', 'papás')
inflect.irregular('mamá', 'mamás')
inflect.irregular('sofá', 'sofás')
end

A minor problem

"oficina de turismo".pluralize
# => "oficina de turismos"

"contacto de emergencia".pluralize
# => "contacto de emergencias"

Lambdas to the rescue
def pluralize(word, locale = nil)
locale ||= I18n.locale
result = word.to_s.dup

# ... elided ...
inflections(locale).plurals.each do |(rule, replacement)|
if replacement.respond_to?(:call)
break if result.gsub!(rule, &replacement)
else
break if result.gsub!(rule, replacement)
end
end
result
end

Lambdas to the rescue

ActiveSupport::Inflector.inflections(:es) do |inflect|
# ... elided ...
inflect.plural(/^(w+)s(.+)$/, lambda { |match|
head, tail = match.split(/s+/, 2)
"#{head.pluralize} #{tail}"
})
# ... elided ...
end

Success!
I18n.locale = :es

"oficina de turismo".pluralize
# => "oficinas de turismo"

"contacto de emergencia".pluralize
# => "contactos de emergencia"

I18n.locale = :en

"emergency contact".pluralize
# => "emergency contacts"

The inﬂector is used everywhere

Because of the wide-spread use of the inﬂector,
we have to patch:
ActiveSupport::ModelName#initialize
String#pluralize, singularize
AS::Inflector#pluralize, singularize, tableize
ActiveRecord::Base.human_name, undecorated_table_name
AR::Reflection::AssociationReflection#derive_class_name
ActionController::PolymorphicRoutes#build_named_route_call

An interesting side-effect
ActiveRecord::Schema.define do
create_table "oficinas_de_turismo" do |t|
t.string "nombre"
t.string "calle"
end
end

context "En español" do
setup { I18n.default_locale = :es }

context "OficinaDeTurismo" do
should("use the right table") {
OficinaDeTurismo.table_name }.equals "oficinas_de_turismo"
end
end

Muchas gracias
a todos!

crnixon@gmail.com
http://crnixon.org
http://github.com/crnixon/traductor
http://delicious.com/crnixon/conferencia.rails+i18n

Advanced Internationalization with Rails

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