Rails defines Yaml files for internationalisation of strings. These are held in config/locales.
The Yaml files contain a set of strings. To access a string from your controller, use: I18n.t 'hello'. In your view, you can use: <%= t('hello') %>
If a string is not defined in your locale, the default locale is used instead. This can be set in application.rb.
Check out Sven Fuchs' rails i18n project for a pretty good basic locale set.
Finding the locale from your URL.
Your locale will not be set for you. You can use your URL to set it, then retrieve it using a filter in application_controller.rb
before_action :set_localedef set_localeI18n.locale = params[:locale] || I18n.default_localeend
Now if you hit a URL like this:
The locale will be set to 'fr' (French).
There are various other options here. You can read about them in the documentation here: http://guides.rubyonrails.org/i18n.html
Exercise: Localise your blog
Create a locale file for a language you know. Now take one of the strings, e.g. 'New Blog Post'. Create a locale file to localise this string.