Ruby i18n - internationalization for ruby

INTERNATIONALIZATION FOR RUBY

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RUBY i18n

INTERNATIONALIZATION FOR PLAIN RUBY: THE RUBY i18n GEM

− Ruby i18n allows translation and localization, interpolation of values to translations,

pluralization, customizable transliteration to ASCII, flexible defaults, bulk lookup, lambdas

as translation data, custom key/scope separator, and custom exception handlers.

− The gem is split in two parts:

− Public API

− Default backend

− YAML (.yml) or plain Ruby (.rb) files are used for storing translations in SimpleStore, still

YAML is the preferred option among Ruby developers.


INTERNATIONALIZATION AND THE YAML RESOURCE FILE FORMAT

KEY FEATURES OF YAML

− Information is stored in key-value pairs delimited with colon ( : )

− Keys can be nested (scoped)

− i18n expects the root key to correspond to the locale of the content

− The “leaf key” has to have a value

− Values can be escaped

− Correct and consistent line indentation is important for preserving the key hierarchy


INTERNATIONALIZATION AND THE YAML RESOURCE FILE FORMAT

KEY FEATURES OF YAML

− Lines starting with a hash tag sign ( # ) preceded with any number of white-space are

ignored by the parser (treated as a comment)

− Place-holder syntax is: %{name}, where “name” can consist of multiple non-white-space

characters

− UTF-8 encoding is usually used for YAML resource files


EXAMPLE YAML FILE


INSTALLATION AND SETUP

1. gem installation

2. Change the directory to the location

where the sample YAML file was saved

and start the irb (interactive ruby shell).

3. Check the current locale. (By default it

is English)

4. Changing it something else is easy.

gem install i18n

2.0.0p247 :001 > require ‘i18n’

=> true

2.0.0p247 :002 > I18n.locale

=> :en

2.0.0p247 :003 > I18n.locale = :de

=> :de


TRANSALTION LOOKUP

− Lookup one of the phrases from our

YAML file example

− The translation is missing because we

haven’t loaded the file. Load all .yml and

.rb files in the current directory.

− Retry accessing the English translation

with the key ‘world’

2.0.0p247 :004 > I18n.translate :world,

:scope => ‘greetings.hello’

=> “translation missing: en.hello.world”

2.0.0p247 :005 > I18n.load_path =

Dir[‘./*.yml, ‘./*.rb’]

=> [“./en.yml”]

2.0.0p247 :006 > I18n.translate :world,

:scope => ‘greetings.hello’

=> “Hello world!”


TRANSALTION LOOKUP

− A local can also be explicitly passed

− When passing the phrase key, a symbol or

string can be used, and a scope can be an

array or dot-separated. Combinations of

them are valid too.

2.0.0p247 :007 > I18n.translate :world, :scope

=> ‘greetings.hello’, :locale => :en

=> “Hello world!”

I18n.translate ‘greetings.hello.world’

I18n.translate ‘hello.world’, :scope =>

:greetings

I18n.translate ‘hello.world’, :scope =>

‘greetings’

I18n.translate :world, :scope =>

‘greetings.hello’

I18n.translate :world, scope: [:greetings,

:hello]


TRANSALTION LOOKUP

− Translate the key :missing and the key

:also_missing

− Variables can be interpolated to the

translation

− Pass an array of keys to look up multiple

translations at once

− A key can translate to a hash of grouped

translations

2.0.0p247 :008 > I18n.translate :missing, default: [:also_missing, ‘Not here’]=> ‘Not here’

2.0.0p247 :009 > I18n.translate :user, :scope => [:greetings, :hello], :user => ‘Ela’=> “Hello Ela!”

2.0.0p247 :010 > I18n.translate [:world, :friend], :scope => [:greetings, :hello]=> [“Hello World!”, “Hello Friend!”]

2.0.0p247 :011 > I18n.translate :hello, :scope => [:greetings] => {:world=>”Hello World!”, :user=>”Hello %{user}”, :friend=>”Hello Friend!”}


PLUARLIZATION OPTION IN i18n FOR RUBY

− The i18n API provides a flexible

pluralization feature adapting to the

different grammar of languages.

− The :count interpolation is interpolated to

the translation and used to pick a

pluralization from the translations

2.0.0p247 :012 > I18n.translate :messages,

:scope => :inbox, :count => 1

=> “You have one message in your inbox.”

2.0.0p247 :013 > I18n.translate :messages,

:scope => :inbox, :count => 39

=> “You have 39 messages in your inbox.”


SETTING UP DATE AND TIME LOCALIZATION

− Pass the Time object to I18n.localize to

localize the time format. Pick a format by

passing the :format option

2.0.0p247 :014 > I18n.localize Time.now

=> “Wed, 14 Aug 2013 13:34:49 +0200”

2.0.0p247 :015 > I18n.localize Time.now,

:format => :short

=> “14 Aug 13:34”


⟶ Instead of I18n.localize, a shorter alias can be used: I18n.l.

i18n – THE DEFAULT INTERNATIONALIZATION SOLUTION FOR RUBY ON RAILS

− Ruby adds all .rb and .yml files from the config/locales directory to translations load path

automatically.

− By default, Rials expects that all the resource files are kept in config/locales.

− You can change some settings by overriding the defaults in application.rb

− Organize the resource files in subdirectories

− Set :de as the default locale

− Set :en, :de and :fr as available locales


Config.i18n.load_path +=

Dir[Rails.root.join(‘config/locales/**/*.{rb,ym

l}’]

config.i18n.default_locale = :de

Config.i18n.available_locales = [:en, :de, :fr]

PASSING THE LOCALE AS A QUERY PARAMETER WITHIN THE URL

− Set the locale in before_action in the

ApplicationController

− This requires passing the locale as a URL

query parameter and adding it to all the

links within the application.

− Rails comes with a helper method that

can be overridden

before_action :set_locale

Def set_locale

I18n.locale = params[:locale] ||

I18n.default_locale

end

# app/controllers/application_controller.rb

def default_url_options(options={})

{ :locale => I18n.locale }

end


PASSING THE LOCALE AS A PART OF THE URL PATH

It is cleaner to have the locale information

at the beginning of the path instead of the

end:

http://localhost:3000/sr/ vs http://localhost:

3000/?locale=sr.

You can do so with the “over-riding

default_url_options” strategy. Just set up the

routes with the scoping option.

# config/routes.rb

scope “(:locale)”, locale: /en|sr/ do

resources :books

end


PASSING THE LOCALE AS A DOMAIN NAME OR A SUBDOMAIN

− Setting the locale from the domain name

or subdomain makes the locale very

obvious and search engines like this

approach too.

− Do so by adding a before_action to the

ApplicationController.

before_action :set_locale

def set_locale

#extracting from the domain name

I18n.locale = extract_locale_from_tld || I18n.default_locale

#extracting from subdomain:

#I18n.locale = extract_locale_from_subdomain || I18n.default_locale

end

def extract_locale_from_tld

parsed_locale = request.host.split('.').last

I18n.available_locales.include?(parsed_locale.to_sym) ?

parsed_locale : nil

end

def extract_locale_from_subdomain

parsed_locale = request.subdomains.first

I18n.available_locales.include?(parsed_locale.to_sym) ?

parsed_locale : nil

end


SETTING THE LOCALE FROM CLIENT-SUPPLIED INFORMATION

− Information other than the page URL can

be used to set the appropriate locale for

the current user.

− An example for a trivial implementation of

using an Accept-Language header


I18n.locale = current_user.locale

def set_locale

I18n.locale =

extract_locale_from_accept_language_header

end

private

def extract_locale_from_accept_language_header

request.env['HTTP_ACCEPT_LANGUAGE'].scan(/

^[a-‐z]{2}/).first

end

TRANSLATION LOOKUP AND DATE/TIME LOCALIZATION BY RUBY ON RAILS

Rails adds t (translate) and l (localize) helper

methods to controllers. They will catch

missing translations and wrap the resulting

error message into a <span>.

#instead of I18n.translate :hello

t :hello

#instead of I18n.localize Time.now

l Time.now


USING SAFE HTML TRANSLATIONS IN RUBY ON RAILS

− Keys with a ‘_html’ suffix and keys named

‘html’ are marked as HTML safe. Use

them without escaping.

#config/locales/en.yml

en:

welcome: <b>welcome!</b>

hello_html: <b>hello!</b>

title:

html: <b>title!</b>

# app/views/home/index.html.erb

<div><%= t(‘welcome’) %></div>

<div><%= raw t(‘welcome’) %></div>

<div><%= t(‘hello_html’) %></div>

<div><%= t(‘title.html’) %></div>


TRANSLATION FOR ACTIVE RECORD MODELS

− Methods Model.model_name.human and

Model.human_attribute_name(attribute)

can be used to transparently look up

translations for model and attribute

names.

en:

activerecord:

models:

user: Dude

attributes:

user:

login: “Handle”

# will translate User

attribute “login” as “Handle”


ERROR MESSAGE SCOPES

For example, if there is an ActiveRecord

model “User” that has the :presence

validation for :name, the key for the

message would be :blank. ActiveRecord will

look up for this key in several namespaces,

in this order:

activerecord.errors.models.[model_name].attr

ibutes.[attribute_name]

activerecord.errors.models.[model_name]

activerecord.errors.messages

errors.attributes.[attribute_name]

errors.messages


SENATRA AND PADRINO


I18n FOR

i18n FOR SINATRA

Set up Sinatra to use i18n gem for

internationalization

require ‘i18n’

require ’i18n/backend/fallbacks’

configure

I18n::Backend::Simple.send(:include,

I18n::Backend::Fallbacks)

I18n.load_path, Dir

[File.join(settings.root, ‘locales’,

‘*.yml’)]

I18n.backend.load_translations

end


i18n FOR SINATRA

before ‘/:locale/*’ do

I18n.locale = params[:locale]

request.path_info = ‘/’ +

params[:splat ] [0]

end

before do

if (locale =

request.host.split(‘.’)[0]) != ‘www’

I18n.locale = locale

end

end

use Rack::Locale


Passing the locale

− Specific URLs

− Dedicated subdomains

i18n FOR SINATRA

use Rack::Locale

helpers dodef t(*args)

I18n.t(*args)end

def l(*args)I18n.l(*args)

endend

helpers dodef find_template(views, name, engine, &block)

I18n.fallbacks[I18n.locale].each { |locale|

super(views, “#{name}.#{locale}”, engine, &block)}

super(views, name, engine, &block)end

end


Passing the locale

− Browser preference (requires rack-contrib)

i18n FOR PADRINO

Localization is fully supported in

− padrino-core (date formats, time formats etc.)

− padrino-admin (admin language, orm fields, orm errors, etc.)

− padrino-helpers (currency, percentage, precision, duration, etc.)

Setting up the default locale in config/boot.rb


Padrino.before_load do

I18n.locale = :en

end

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ANJA OBERMÜLLERBUSINESS DEVELOPMENT & MARKETING AT LINGOHUB

[email protected]@LingoHub@anjaobermuellerRead the whole article.


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