Ruby on Rails i18n
Ruby on Rails i18n: Convention-Based Translation Management
Ruby on Rails includes a built-in I18n API that uses YAML locale files to manage translations. The framework follows convention over configuration, with lazy lookup in views, automatic pluralization rules, and interpolation support. Rails provides locale-aware helpers for dates, numbers, and currencies out of the box, and its fallback system ensures missing translations degrade gracefully.
Ruby on Rails i18n Features
YAML locale files in config/locales with nested key organization
I18n.t() and I18n.l() API for translations and locale-aware formatting
Built-in pluralization with one/other rules and custom plural backends
Variable interpolation with %{variable} syntax in translation strings
Lazy lookup with t('.key') in views for automatic scope resolution
Fallback locale chains for graceful handling of missing translations
Translated routes and URL helpers with route_translator or similar gems
ActiveRecord model translations for database-backed multilingual content
Locale-aware date, time, number, and currency formatting helpers
Rails i18n in Practice
Define translations in YAML locale files, use t() in controllers and views with interpolation, and render localized content in ERB templates.
# config/locales/en.yml
en:
welcome: "Welcome to %{app_name}"
items:
one: "%{count} item"
other: "%{count} items"
# app/controllers/home_controller.rb
class HomeController < ApplicationController
def index
@welcome = t('welcome', app_name: 'My App')
@items = t('items', count: 5)
end
end
# app/views/home/index.html.erb
<h1><%= @welcome %></h1>
<p><%= @items %></p>Related Guides
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