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Touch-up the 'i18n' part while reading the first two sections.

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Andreas Scherer 2009-03-09 18:31:51 +01:00
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@ -12,8 +12,8 @@ So, in the process of _internationalizing_ your Rails application you have to:
In the process of _localizing_ your application you'll probably want to do following three things:
* Replace or supplement Rails' default locale -- eg. date and time formats, month names, ActiveRecord model names, etc
* Abstract texts in your application into keyed dictionaries -- eg. flash messages, static texts in your views, etc
* Replace or supplement Rails' default locale -- e.g. date and time formats, month names, ActiveRecord model names, etc
* Abstract texts in your application into keyed dictionaries -- e.g. flash messages, static texts in your views, etc
* Store the resulting dictionaries somewhere
This guide will walk you through the I18n API and contains a tutorial how to internationalize a Rails application from the start.
@ -24,12 +24,12 @@ NOTE: The Ruby I18n framework provides you with all neccessary means for interna
h3. How I18n in Ruby on Rails works
Internationalization is a complex problem. Natural languages differ in so many ways (eg. in pluralization rules) that it is hard to provide tools for solving all problems at once. For that reason the Rails I18n API focuses on:
Internationalization is a complex problem. Natural languages differ in so many ways (e.g. in pluralization rules) that it is hard to provide tools for solving all problems at once. For that reason the Rails I18n API focuses on:
* providing support for English and similar languages out of the box
* making it easy to customize and extend everything for other languages
As part of this solution, *every static string in the Rails framework* -- eg. Active Record validation messages, time and date formats -- *has been internationalized*, so _localization_ of a Rails application means "over-riding" these defaults.
As part of this solution, *every static string in the Rails framework* -- e.g. Active Record validation messages, time and date formats -- *has been internationalized*, so _localization_ of a Rails application means "over-riding" these defaults.
h4. The overall architecture of the library
@ -89,15 +89,15 @@ en:
This means, that in the +:en+ locale, the key _hello_ will map to _Hello world_ string. Every string inside Rails is internationalized in this way, see for instance Active Record validation messages in the "+activerecord/lib/active_record/locale/en.yml+":http://github.com/rails/rails/blob/master/activerecord/lib/active_record/locale/en.yml file or time and date formats in the "+activesupport/lib/active_support/locale/en.yml+":http://github.com/rails/rails/blob/master/activesupport/lib/active_support/locale/en.yml file. You can use YAML or standard Ruby Hashes to store translations in the default (Simple) backend.
The I18n library will use *English* as a *default locale*, ie. if you don't set a different locale, +:en+ will be used for looking up translations.
The I18n library will use *English* as a *default locale*, i.e. if you don't set a different locale, +:en+ will be used for looking up translations.
NOTE: The i18n library takes *pragmatic approach* to locale keys (after "some discussion":http://groups.google.com/group/rails-i18n/browse_thread/thread/14dede2c7dbe9470/80eec34395f64f3c?hl=en), including only the _locale_ ("language") part, like +:en+, +:pl+, not the _region_ part, like +:en-US+ or +:en-UK+, which are traditionally used for separating "languages" and "regional setting" or "dialects". Many international applications use only the "language" element of a locale such as +:cz+, +:th+ or +:es+ (for Czech, Thai and Spanish). However, there are also regional differences within different language groups that may be important. For instance, in the +:en-US+ locale you would have $ as a currency symbol, while in +:en-UK+, you would have £. Nothing stops you from separating regional and other settings in this way: you just have to provide full "English - United Kingdom" locale in a +:en-UK+ dictionary. Various "Rails I18n plugins":http://rails-i18n.org/wiki such as "Globalize2":http://github.com/joshmh/globalize2 may help you implement it.
NOTE: The i18n library takes a *pragmatic approach* to locale keys (after "some discussion":http://groups.google.com/group/rails-i18n/browse_thread/thread/14dede2c7dbe9470/80eec34395f64f3c?hl=en), including only the _locale_ ("language") part, like +:en+, +:pl+, not the _region_ part, like +:en-US+ or +:en-UK+, which are traditionally used for separating "languages" and "regional setting" or "dialects". Many international applications use only the "language" element of a locale such as +:cz+, +:th+ or +:es+ (for Czech, Thai and Spanish). However, there are also regional differences within different language groups that may be important. For instance, in the +:en-US+ locale you would have $ as a currency symbol, while in +:en-UK+, you would have £. Nothing stops you from separating regional and other settings in this way: you just have to provide full "English - United Kingdom" locale in a +:en-UK+ dictionary. Various "Rails I18n plugins":http://rails-i18n.org/wiki such as "Globalize2":http://github.com/joshmh/globalize2 may help you implement it.
The *translations load path* (+I18n.load_path+) is just a Ruby Array of paths to your translation files that will be loaded automatically and available in your application. You can pick whatever directory and translation file naming scheme makes sense for you.
NOTE: The backend will lazy-load these translations when a translation is looked up for the first time. This makes it possible to just swap the backend with something else even after translations have already been announced.
The default +environment.rb+ files has instruction how to add locales from another directory and how to set different default locale. Just uncomment and edit the specific lines.
The default +environment.rb+ files has instruction how to add locales from another directory and how to set a different default locale. Just uncomment and edit the specific lines.
<ruby>
# The internationalization framework can be changed
@ -129,9 +129,9 @@ If you want to translate your Rails application to a *single language other than
However, you would probably like to *provide support for more locales* in your application. In such case, you need to set and pass the locale between requests.
WARNING: You may be tempted to store choosed locale in a _session_ or a _cookie_. *Do not do so*. The locale should be transparent and a part of the URL. This way you don't break people's basic assumptions about the web itself: if you send a URL of some page to a friend, she should see the same page, same content. A fancy word for this would be that you're being "_RESTful_":http://en.wikipedia.org/wiki/Representational_State_Transfer. Read more about RESTful approach in "Stefan Tilkov's articles":http://www.infoq.com/articles/rest-introduction. There may be some exceptions to this rule, which are discussed below.
WARNING: You may be tempted to store the chosen locale in a _session_ or a _cookie_. *Do not do so*. The locale should be transparent and a part of the URL. This way you don't break people's basic assumptions about the web itself: if you send a URL of some page to a friend, she should see the same page, same content. A fancy word for this would be that you're being "_RESTful_":http://en.wikipedia.org/wiki/Representational_State_Transfer. Read more about the RESTful approach in "Stefan Tilkov's articles":http://www.infoq.com/articles/rest-introduction. There may be some exceptions to this rule, which are discussed below.
The _setting part_ is easy. You can set locale in a +before_filter+ in the ApplicationController like this:
The _setting part_ is easy. You can set the locale in a +before_filter+ in the ApplicationController like this:
<ruby>
before_filter :set_locale
@ -141,13 +141,13 @@ def set_locale
end
</ruby>
This requires you to pass the locale as a URL query parameter as in +http://example.com/books?locale=pt+. (This is eg. Google's approach). So +http://localhost:3000?locale=pt+ will load the Portugese localization, whereas +http://localhost:3000?locale=de+ would load the German localization, and so on. You may skip the next section and head over to the *Internationalize your application* section, if you want to try things out by manually placing locale in the URL and reloading the page.
This requires you to pass the locale as a URL query parameter as in +http://example.com/books?locale=pt+. (This is, for example, Google's approach.) So +http://localhost:3000?locale=pt+ will load the Portugese localization, whereas +http://localhost:3000?locale=de+ would load the German localization, and so on. You may skip the next section and head over to the *Internationalize your application* section, if you want to try things out by manually placing the locale in the URL and reloading the page.
Of course, you probably don't want to manually include locale in every URL all over your application, or want the URLs look differently, eg. the usual +http://example.com/pt/books+ versus +http://example.com/en/books+. Let's discuss the different options you have.
Of course, you probably don't want to manually include the locale in every URL all over your application, or want the URLs look differently, e.g. the usual +http://example.com/pt/books+ versus +http://example.com/en/books+. Let's discuss the different options you have.
IMPORTANT: Following examples rely on having locales loaded into your application available as an array of strings like +["en", "es", "gr"]+. This is not inclued in current version of Rails 2.2 -- forthcoming Rails version 2.3 will contain easy accesor +available_locales+. (See "this commit":http://github.com/svenfuchs/i18n/commit/411f8fe7 and background at "Rails I18n Wiki":http://rails-i18n.org/wiki/pages/i18n-available_locales.)
IMPORTANT: The following examples rely on having available locales loaded into your application as an array of strings like +["en", "es", "gr"]+. This is not included in the current version of Rails 2.2 -- the forthcoming Rails version 2.3 will contain the easy accessor +available_locales+. (See "this commit":http://github.com/svenfuchs/i18n/commit/411f8fe7 and background at "Rails I18n Wiki":http://rails-i18n.org/wiki/pages/i18n-available_locales.)
So, for having available locales easily available in Rails 2.2, we have to include this support manually in an initializer, like this:
So, for having available locales easily accessible in Rails 2.2, we have to include this support manually in an initializer, like this:
<ruby>
# config/initializers/available_locales.rb
@ -180,11 +180,11 @@ class ApplicationController < ActionController::Base
end
</ruby>
h4. Setting locale from the domain name
h4. Setting the locale from the domain name
One option you have is to set the locale from the domain name where your application runs. For example, we want +www.example.com+ to load English (or default) locale, and +www.example.es+ to load Spanish locale. Thus the _top-level domain name_ is used for locale setting. This has several advantages:
One option you have is to set the locale from the domain name where your application runs. For example, we want +www.example.com+ to load the English (or default) locale, and +www.example.es+ to load the Spanish locale. Thus the _top-level domain name_ is used for locale setting. This has several advantages:
* Locale is an _obvious_ part of the URL
* The locale is an _obvious_ part of the URL
* People intuitively grasp in which language the content will be displayed
* It is very trivial to implement in Rails
* Search engines seem to like that content in different languages lives at different, inter-linked domains
@ -208,7 +208,7 @@ def extract_locale_from_tld
end
</ruby>
We can also set the locale from the _subdomain_ in very similar way:
We can also set the locale from the _subdomain_ in a very similar way:
<ruby>
# Get locale code from request subdomain (like http://it.application.local:3000)
@ -231,15 +231,15 @@ assuming you would set +APP_CONFIG[:deutsch_website_url]+ to some value like +ht
This solution has aforementioned advantages, however, you may not be able or may not want to provide different localizations ("language versions") on different domains. The most obvious solution would be to include locale code in the URL params (or request path).
h4. Setting locale from the URL params
h4. Setting the locale from the URL params
Most usual way of setting (and passing) the locale would be to include it in URL params, as we did in the +I18n.locale = params[:locale]+ _before_filter_ in the first example. We would like to have URLs like +www.example.com/books?locale=ja+ or +www.example.com/ja/books+ in this case.
The most usual way of setting (and passing) the locale would be to include it in URL params, as we did in the +I18n.locale = params[:locale]+ _before_filter_ in the first example. We would like to have URLs like +www.example.com/books?locale=ja+ or +www.example.com/ja/books+ in this case.
This approach has almost the same set of advantages as setting the locale from domain name: namely that it's RESTful and in accord with rest of the World Wide Web. It does require a little bit more work to implement, though.
This approach has almost the same set of advantages as setting the locale from the domain name: namely that it's RESTful and in accord with the rest of the World Wide Web. It does require a little bit more work to implement, though.
Getting the locale from +params+ and setting it accordingly is not hard; including it in every URL and thus *passing it through the requests* is. To include an explicit option in every URL (eg. +link_to( books_url(:locale => I18n.locale) )+) would be tedious and probably impossible, of course.
Getting the locale from +params+ and setting it accordingly is not hard; including it in every URL and thus *passing it through the requests* is. To include an explicit option in every URL (e.g. +link_to( books_url(:locale => I18n.locale))+) would be tedious and probably impossible, of course.
Rails contains infrastructure for "centralizing dynamic decisions about the URLs" in its "+*ApplicationController#default_url_options*+":http://api.rubyonrails.org/classes/ActionController/Base.html#M000515, which is useful precisely in this scenario: it enables us to set "defaults" for "+url_for+":http://api.rubyonrails.org/classes/ActionController/Base.html#M000503 and helper methods dependent on it (by implementing/overriding this method).
Rails contains infrastructure for "centralizing dynamic decisions about the URLs" in its "+ApplicationController#default_url_options+":http://api.rubyonrails.org/classes/ActionController/Base.html#M000515, which is useful precisely in this scenario: it enables us to set "defaults" for "+url_for+":http://api.rubyonrails.org/classes/ActionController/Base.html#M000503 and helper methods dependent on it (by implementing/overriding this method).
We can include something like this in our ApplicationController then:
@ -251,20 +251,20 @@ def default_url_options(options={})
end
</ruby>
Every helper method dependent on +url_for+ (eg. helpers for named routes like +root_path+ or +root_url+, resource routes like +books_path+ or +books_url+, etc.) will now *automatically include the locale in the query string*, like this: +http://localhost:3001/?locale=ja+.
Every helper method dependent on +url_for+ (e.g. helpers for named routes like +root_path+ or +root_url+, resource routes like +books_path+ or +books_url+, etc.) will now *automatically include the locale in the query string*, like this: +http://localhost:3001/?locale=ja+.
You may be satisfied with this. It does impact the readability of URLs, though, when the locale "hangs" at the end of every URL in your application. Moreover, from the architectural standpoint, locale is usually hierarchically above the other parts of application domain: and URLs should reflect this.
You may be satisfied with this. It does impact the readability of URLs, though, when the locale "hangs" at the end of every URL in your application. Moreover, from the architectural standpoint, locale is usually hierarchically above the other parts of the application domain: and URLs should reflect this.
You probably want URLs look like this: +www.example.com/en/books+ (which loads English locale) and +www.example.com/nl/books+ (which loads Netherlands locale). This is achievable with the "over-riding +default_url_options+" strategy from above: you just have to set up your routes with "+path_prefix+":http://api.rubyonrails.org/classes/ActionController/Resources.html#M000354 option in this way:
You probably want URLs to look like this: +www.example.com/en/books+ (which loads the English locale) and +www.example.com/nl/books+ (which loads the Netherlands locale). This is achievable with the "over-riding +default_url_options+" strategy from above: you just have to set up your routes with "+path_prefix+":http://api.rubyonrails.org/classes/ActionController/Resources.html#M000354 option in this way:
<ruby>
# config/routes.rb
map.resources :books, :path_prefix => '/:locale'
</ruby>
Now, when you call +books_path+ method you should get +"/en/books"+ (for the default locale). An URL like +http://localhost:3001/nl/books+ should load the Netherlands locale, then, and following calls to +books_path+ should return +"/nl/books"+ (because the locale changed).
Now, when you call the +books_path+ method you should get +"/en/books"+ (for the default locale). An URL like +http://localhost:3001/nl/books+ should load the Netherlands locale, then, and following calls to +books_path+ should return +"/nl/books"+ (because the locale changed).
Of course, you need to take special care of root URL (usually "homepage" or "dashboard") of your application. An URL like +http://localhost:3001/nl+ will not work automatically, because the +map.root :controller => "dashboard"+ declaration in your +routes.rb+ doesn't take locale into account. (And rightly so. There's only one "root" URL.)
Of course, you need to take special care of the root URL (usually "homepage" or "dashboard") of your application. An URL like +http://localhost:3001/nl+ will not work automatically, because the +map.root :controller => "dashboard"+ declaration in your +routes.rb+ doesn't take locale into account. (And rightly so: there's only one "root" URL.)
You would probably need to map URLs like these:
@ -275,18 +275,18 @@ map.dashboard '/:locale', :controller => "dashboard"
Do take special care about the *order of your routes*, so this route declaration does not "eat" other ones. (You may want to add it directly before the +map.root+ declaration.)
IMPORTANT: This solution has currently one rather big *downside*. Due to the _default_url_options_ implementation, you have to pass the +:id+ option explicitely, like this: +link_to 'Show', book_url(:id => book)+ and not depend on Rails' magic in code like +link_to 'Show', book+. If this should be a problem, have a look on two plugins which simplify working with routes in this way: Sven Fuchs's "_routing_filter_":http://github.com/svenfuchs/routing-filter/tree/master and Raul Murciano's "_translate_routes_":http://github.com/raul/translate_routes/tree/master. See also the page "How to encode the current locale in the URL":http://rails-i18n.org/wiki/pages/how-to-encode-the-current-locale-in-the-url in the Rails i18n Wiki.
IMPORTANT: This solution has currently one rather big *downside*. Due to the _default_url_options_ implementation, you have to pass the +:id+ option explicitely, like this: +link_to 'Show', book_url(:id => book)+ and not depend on Rails' magic in code like +link_to 'Show', book+. If this should be a problem, have a look at two plugins which simplify work with routes in this way: Sven Fuchs's "routing_filter":http://github.com/svenfuchs/routing-filter/tree/master and Raul Murciano's "translate_routes":http://github.com/raul/translate_routes/tree/master. See also the page "How to encode the current locale in the URL":http://rails-i18n.org/wiki/pages/how-to-encode-the-current-locale-in-the-url in the Rails i18n Wiki.
h4. Setting locale from the client supplied information
h4. Setting the locale from the client supplied information
In specific cases, it would make sense to set locale from client supplied information, ie. not from URL. This information may come for example from users' preffered language (set in their browser), can be based on users' geographical location inferred from their IP, or users can provide it simply by choosing locale in your application interface and saving it to their profile. This approach is more suitable for web-based applications or services, not for websites -- see the box about _sessions_, _cookies_ and RESTful architecture above.
In specific cases, it would make sense to set the locale from client-supplied information, i.e. not from the URL. This information may come for example from the users' prefered language (set in their browser), can be based on the users' geographical location inferred from their IP, or users can provide it simply by choosing the locale in your application interface and saving it to their profile. This approach is more suitable for web-based applications or services, not for websites -- see the box about _sessions_, _cookies_ and RESTful architecture above.
h5. Using Accept-Language
One source of client supplied information would be an +Accept-Language+ HTTP header. People may "set this in their browser":http://www.w3.org/International/questions/qa-lang-priorities or other clients (such as _curl_).
A trivial implementation of using +Accept-Language+ header would be:
A trivial implementation of using an +Accept-Language+ header would be:
<ruby>
def set_locale
@ -300,21 +300,21 @@ def extract_locale_from_accept_language_header
end
</ruby>
Of course, in production environment you would need much robust code, and could use a plugin such as Iaian Hecker's "http_accept_language":http://github.com/iain/http_accept_language or even Rack middleware such as Ryan Tomayko's "locale":http://github.com/rtomayko/rack-contrib/blob/master/lib/rack/locale.rb.
Of course, in a production environment you would need much more robust code, and could use a plugin such as Iaian Hecker's "http_accept_language":http://github.com/iain/http_accept_language or even Rack middleware such as Ryan Tomayko's "locale":http://github.com/rtomayko/rack-contrib/blob/master/lib/rack/locale.rb.
h5. Using GeoIP (or similar) database
Another way of choosing the locale from client's information would be to use a database for mapping client IP to region, such as "GeoIP Lite Country":http://www.maxmind.com/app/geolitecountry. The mechanics of the code would be very similar to the code above -- you would need to query database for user's IP, and lookup your preffered locale for the country/region/city returned.
Another way of choosing the locale from client information would be to use a database for mapping the client IP to the region, such as "GeoIP Lite Country":http://www.maxmind.com/app/geolitecountry. The mechanics of the code would be very similar to the code above -- you would need to query the database for the user's IP, and lookup your prefered locale for the country/region/city returned.
h5. User profile
You can also provide users of your application with means to set (and possibly over-ride) locale in your application interface, as well. Again, mechanics for this approach would be very similar to the code above -- you'd probably let users choose a locale from a dropdown list and save it to their profile in database. Then you'd set the locale to this value.
You can also provide users of your application with means to set (and possibly over-ride) the locale in your application interface, as well. Again, mechanics for this approach would be very similar to the code above -- you'd probably let users choose a locale from a dropdown list and save it to their profile in the database. Then you'd set the locale to this value.
h3. Internationalizing your application
OK! Now you've initialized I18n support for your Ruby on Rails application and told it which locale should be used and how to preserve it between requests. With that in place, you're now ready for the really interesting stuff.
Let's _internationalize_ our application, ie. abstract every locale-specific parts, and that _localize_ it, ie. provide neccessary translations for these abstracts.
Let's _internationalize_ our application, i.e. abstract every locale-specific parts, and that _localize_ it, i.e. provide neccessary translations for these abstracts.
You most probably have something like this in one of your applications:
@ -418,7 +418,7 @@ h4. Localized views
Rails 2.3 brings one convenient feature: localized views (templates). Let's say you have a _BooksController_ in your application. Your _index_ action renders content in +app/views/books/index.html.erb+ template. When you put a _localized variant_ of this template: *+index.es.html.erb+* in the same directory, Rails will render content in this template, when the locale is set to +:es+. When the locale is set to the default locale, generic +index.html.erb+ view will be used. (Future Rails versions may well bring this _automagic_ localization to assets in +public+, etc.)
You can make use this feature eg. when working with great amount of static content, which would be clumsy to put inside YAML or Ruby dictionaries. Bear in mind, though, that any change you would like to do later to the template must be propagated to all of them.
You can make use this feature e.g. when working with great amount of static content, which would be clumsy to put inside YAML or Ruby dictionaries. Bear in mind, though, that any change you would like to do later to the template must be propagated to all of them.
h4. Organization of locale files
@ -449,7 +449,7 @@ For example, your +config/locale+ directory could look like this:
|-----en.rb
</pre>
This way, you can separate model and model attribute names from text inside views, and all of this from the "defaults" (eg. date and time formats). Other stores for the i18n library could provide different means of such separation.
This way, you can separate model and model attribute names from text inside views, and all of this from the "defaults" (e.g. date and time formats). Other stores for the i18n library could provide different means of such separation.
NOTE: The default locale loading mechanism in Rails does not load locale files in nested dictionaries, like we have here. So, for this to work, we must explicitely tell Rails to look further: