Merge branch 'master' of git@github.com:lifo/docrails

4 files changed, 332 insertions, 174 deletions

diff --git a/railties/doc/guides/source/creating_plugins/appendix.txt b/railties/doc/guides/source/creating_plugins/appendix.txt
index 340c03dd4e..7cb8109372 100644
--- a/railties/doc/guides/source/creating_plugins/appendix.txt
+++ b/railties/doc/guides/source/creating_plugins/appendix.txt
@@ -5,7 +5,7 @@ If you prefer to use RSpec instead of Test::Unit, you may be interested in the h
 === References ===
 
  * http://nubyonrails.com/articles/the-complete-guide-to-rails-plugins-part-i
- * http://nubyonrails.com/articles/2006/05/09/the-complete-guide-to-rails-plugins-part-ii
+ * http://nubyonrails.com/articles/the-complete-guide-to-rails-plugins-part-ii
  * http://github.com/technoweenie/attachment_fu/tree/master
  * http://daddy.platte.name/2007/05/rails-plugins-keep-initrb-thin.html
  * http://www.mbleigh.com/2008/6/11/gemplugins-a-brief-introduction-to-the-future-of-rails-plugins
diff --git a/railties/doc/guides/source/form_helpers.txt b/railties/doc/guides/source/form_helpers.txt
index d60ed10a39..f4039070dd 100644
--- a/railties/doc/guides/source/form_helpers.txt
+++ b/railties/doc/guides/source/form_helpers.txt
@@ -14,8 +14,8 @@ In this guide you will:
 NOTE: This guide is not intended to be a complete documentation of available form helpers and their arguments. Please visit http://api.rubyonrails.org/[the Rails API documentation] for a complete reference.
 
 
-Basic forms
------------
+Dealing With Basic Forms
+------------------------
 
 The most basic form helper is `form_tag`.
 
@@ -113,9 +113,23 @@ This is a common pitfall when using form helpers, since many of them accept mult
 
 WARNING: Do not delimit the second hash without doing so with the first hash, otherwise your method invocation will result in an `expecting tASSOC` syntax error.
 
-Checkboxes, radio buttons and other controls
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Helpers for generating form elements
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Rails provides a series of helpers for generating form elements such as checkboxes, text fields, radio buttons and so. These basic helpers, with names ending in _tag such as `text_field_tag`, `check_box_tag` just generate a single `<input>` element. The first parameter to these is always the name of the input. This is the name under which value will appear in the `params` hash in the controller. For example if the form contains
+
+---------------------------
+<%= text_field_tag(:query) %>
+---------------------------
+
+then the controller code should use
+---------------------------
+params[:query]
+---------------------------
+to retrieve the value entered by the user. When naming inputs be aware that Rails uses certain conventions that control whether values appear at the top level of the params hash, inside an array or a nested hash and so on. You can read more about them in the <<parameter_names,parameter names>> section. For details on the precise usage of these helpers, please refer to the http://api.rubyonrails.org/classes/ActionView/Helpers/FormTagHelper.html[API documentation].
 
+Checkboxes
+^^^^^^^^^^
 Checkboxes are form controls that give the user a set of options they can enable or disable:
 
 ----------------------------------------------------------------------------
@@ -132,6 +146,10 @@ output:
   <label for="pet_cat">I own a cat</label>
 ----------------------------------------------------------------------------
 
+The second parameter to `check_box_tag` is the value of the input. This is the value that will be submitted by the browser if the checkbox is ticked (i.e. the value that will be present in the params hash). With the above form you would check the value of `params[:pet_dog]` and `params[:pet_cat]` to see which pets the user owns.
+
+Radio buttons
+^^^^^^^^^^^^^
 Radio buttons, while similar to checkboxes, are controls that specify a set of options in which they are mutually exclusive (user can only pick one):
 
 ----------------------------------------------------------------------------
@@ -148,9 +166,13 @@ output:
   <label for="age_adult">I'm over 21</label>
 ----------------------------------------------------------------------------
 
+As with `check_box_tag` the second parameter to `radio_button_tag` is the value of the input. Because these two radio buttons share the same name (age) the user will only be able to select one and `params[:age]` will contain either `child` or `adult`.
+
 IMPORTANT: Always use labels for each checkbox and radio button. They associate text with a specific option and provide a larger clickable region.
 
-Other form controls worth mentioning  are the text area, password input and hidden input:
+Other helpers of interest
+^^^^^^^^^^^^^^^^^^^^^^^^^
+Other form controls worth mentioning are the text area, password input and hidden input:
 
 ----------------------------------------------------------------------------
 <%= text_area_tag(:message, "Hi, nice site", :size => "24x6") %>
@@ -164,55 +186,20 @@ output:
 <input id="parent_id" name="parent_id" type="hidden" value="5" />
 ----------------------------------------------------------------------------
 
-Hidden inputs are not shown to the user, but they hold data same as any textual input. Values inside them can be changed with JavaScript.
+Hidden inputs are not shown to the user, but they hold data like any textual input. Values inside them can be changed with JavaScript.
 
 TIP: If you're using password input fields (for any purpose), you might want to prevent their values showing up in application logs by activating `filter_parameter_logging(:password)` in your ApplicationController.
 
-How do forms with PUT or DELETE methods work?
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-Rails framework encourages RESTful design of your applications, which means you'll be making a lot of "PUT" and "DELETE" requests (besides "GET" and "POST"). Still, most browsers _don't support_ methods other than "GET" and "POST" when it comes to submitting forms. How does this work, then?
-
-Rails works around this issue by emulating other methods over POST with a hidden input named `"_method"` that is set to reflect the desired method:
-
-----------------------------------------------------------------------------
-form_tag(search_path, :method => "put")
-  
-output:
-
-<form action="/search" method="post">
-  <div style="margin:0;padding:0">
-    <input name="_method" type="hidden" value="put" />
-    <input name="authenticity_token" type="hidden" value="f755bb0ed134b76c432144748a6d4b7a7ddf2b71" />
-  </div>
-  ...
-----------------------------------------------------------------------------
-
-When parsing POSTed data, Rails will take into account the special `_method` parameter and act as if the HTTP method was the one specified inside it ("PUT" in this example).
 
-Different Families of helpers
-------------------------------
-
-Most of Rails' form helpers are available in two forms.
-
-Barebones helpers
-~~~~~~~~~~~~~~~~~~
-These just generate the appropriate markup. These have names ending in _tag such as `text_field_tag`, `check_box_tag`. The first parameter to these is always the name of the input. This is the name under which value will appear in the `params` hash in the controller. For example if the form contains
----------------------------
-<%= text_field_tag(:query) %>
----------------------------
-
-then the controller code should use
----------------------------
-params[:query]
----------------------------
-to retrieve the value entered by the user. When naming inputs be aware that Rails uses certain conventions that control whether values appear at the top level of the params hash, inside an array or a nested hash and so on. You can read more about them in the <<parameter_names,parameter names>> section. For details on the precise usage of these helpers, please refer to the http://api.rubyonrails.org/classes/ActionView/Helpers/FormTagHelper.html[API documentation].
+Dealing With Model Objects
+--------------------------
 
 Model object helpers
-~~~~~~~~~~~~~~~~~~~~~
-These are designed to work with a model object (commonly an Active Record object but this need not be the case). These lack the _tag suffix, for example `text_field`, `text_area`.
+~~~~~~~~~~~~~~~~~~~~~~
 
-For these helpers the first arguement is the name of an instance variable and the second is the name a method (usually an attribute) to call on that object. Rails will set the value of the input control to the return value of that method for the object and set an appropriate input name. If your controller has defined `@person` and that person's name is Henry then a form containing:
+A particularly common task for a form is editing or creating a model object. While the `*_tag` helpers could certainly be used for this task they are somewhat verbose as for each tag you would have to ensure the correct parameter name is used and set the default value of the input appropriately. Rails provides helpers tailored to this task. These helpers lack the _tag suffix, for example `text_field`, `text_area`.
+
+For these helpers the first argument is the name of an instance variable and the second is the name of a method (usually an attribute) to call on that object. Rails will set the value of the input control to the return value of that method for the object and set an appropriate input name. If your controller has defined `@person` and that person's name is Henry then a form containing:
 
 ---------------------------
 <%= text_field(:person, :name) %>
@@ -227,10 +214,15 @@ Upon form submission the value entered by the user will be stored in `params[:pe
 ============================================================================
 You must pass the name of an instance variable, i.e. `:person` or `"person"`, not an actual instance of your model object.
 ============================================================================
-Forms that deal with model attributes
--------------------------------------
 
-While the helpers seen so far are handy Rails can save you some work. For example typically a form is used to edit multiple attributes of a single object, so having to repeat the name of the object being edited is clumsy. The following examples will handle an Article model. First, have the controller create one:
+Rails provides helpers for displaying the validation errors associated with a model object. These are covered in detail by the link:./activerecord_validations_callbacks.html#_using_the_tt_errors_tt_collection_in_your_view_templates[Active Record Validations and Callbacks] guide.
+
+Binding a form to an object
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+While this is an increase in comfort it is far from perfect. If Person has many attributes to edit then we would be repeating the name of the edited object many times. What we want to do is somehow bind a form to a model object which is exactly what `form_for` does.
+
+Assume we have a controller for dealing with articles:
 
 .articles_controller.rb
 ----------------------------------------------------------------------------
@@ -239,7 +231,7 @@ def new
 end
 ----------------------------------------------------------------------------
 
-Now switch to the view. The first thing to remember is to use the `form_for` helper instead of `form_tag`, and that you should pass the model name and object as arguments:
+The corresponding view using `form_for` looks like this
 
 .articles/new.html.erb
 ----------------------------------------------------------------------------
@@ -252,9 +244,9 @@ Now switch to the view. The first thing to remember is to use the `form_for` hel
 
 There are a few things to note here:
 
-1. `:article` is the name of the model and `@article` is the record.
+1. `:article` is the name of the model and `@article` is the actual object being edited.
 2. There is a single hash of options. Routing options are passed inside `:url` hash, HTML options are passed in the `:html` hash.
-3. The `form_for` method yields *a form builder* object (the `f` variable).
+3. The `form_for` method yields a *form builder* object (the `f` variable).
 4. Methods to create form controls are called *on* the form builder object `f`
 
 The resulting HTML is:
@@ -270,10 +262,30 @@ The name passed to `form_for` controls where in the params hash the form values
 
 The helper methods called on the form builder are identical to the model object helpers except that it is not necessary to specify which object is being edited since this is already managed by the form builder.
 
+You can create a similar binding without actually creating  `<form>` tags with the `fields_for` helper. This is useful for editing additional model objects with the same form. For example if you had a Person model with an associated ContactDetail model you could create a form for editing both like so:
+-------------
+<% form_for @person do |person_form| %>
+  <%= person_form.text_field :name %>
+  <% fields_for @person.contact_detail do |contact_details_form| %>
+    <%= contact_details_form.text_field :phone_number %>
+  <% end %>
+<% end %>
+-------------
+
+which produces the following output:
+
+-------------
+<form action="/people/1" class="edit_person" id="edit_person_1" method="post">
+  <input id="person_name" name="person[name]" size="30" type="text" />  
+  <input id="contact_detail_phone_number" name="contact_detail[phone_number]" size="30" type="text" />
+</form>
+-------------
+The object yielded by `fields_for` is a form builder like the one yielded by `form_for` (in fact `form_for` calls `fields_for` internally).
+
 Relying on record identification
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-In the previous chapter you handled the Article model. This model is directly available to users of our application, so -- following the best practices for developing with Rails -- you should declare it *a resource*.
+The Article model is directly available to users of our application, so -- following the best practices for developing with Rails -- you should declare it *a resource*.
 
 When dealing with RESTful resources, calls to `form_for` can get significantly easier if you rely on *record identification*. In short, you can just pass the model instance and have Rails figure out model name and the rest:
 
@@ -309,15 +321,37 @@ will create a form that submits to the articles controller inside the admin name
 -------
 form_for [:admin, :management, @article]
 ------- 
-For more information on Rails' routing system and the associated conventions, please see the link:../routing_outside_in.html[routing guide].
+For more information on Rails' routing system and the associated conventions, please see the link:./routing_outside_in.html[routing guide].
+
+
+How do forms with PUT or DELETE methods work?
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Rails framework encourages RESTful design of your applications, which means you'll be making a lot of "PUT" and "DELETE" requests (besides "GET" and "POST"). Still, most browsers _don't support_ methods other than "GET" and "POST" when it comes to submitting forms. How does this work, then?
+
+Rails works around this issue by emulating other methods over POST with a hidden input named `"_method"` that is set to reflect the desired method:
+
+----------------------------------------------------------------------------
+form_tag(search_path, :method => "put")
+  
+output:
+
+<form action="/search" method="post">
+  <div style="margin:0;padding:0">
+    <input name="_method" type="hidden" value="put" />
+    <input name="authenticity_token" type="hidden" value="f755bb0ed134b76c432144748a6d4b7a7ddf2b71" />
+  </div>
+  ...
+----------------------------------------------------------------------------
+When parsing POSTed data, Rails will take into account the special `_method` parameter and act as if the HTTP method was the one specified inside it ("PUT" in this example).
 
 
 Making select boxes with ease
 -----------------------------
 
-Select boxes in HTML require a significant amount of markup (one `OPTION` element for each option to choose from), therefore it makes the most sense for them to be dynamically generated from data stored in arrays or hashes.
+Select boxes in HTML require a significant amount of markup (one `OPTION` element for each option to choose from), therefore it makes the most sense for them to be dynamically generated.
 
-Here is what our wanted markup might look like:
+Here is what the markup might look like:
 
 ----------------------------------------------------------------------------
 <select name="city_id" id="city_id">
@@ -328,7 +362,7 @@ Here is what our wanted markup might look like:
 </select>
 ----------------------------------------------------------------------------
 
-Here you have a list of cities where their names are presented to the user, but internally the application only wants to handle their IDs so they are used as the options' value attributes. Let's see how Rails can help out here.
+Here you have a list of cities whose names are presented to the user. Internally the application only wants to handle their IDs so they are used as the options' value attribute. Let's see how Rails can help out here.
 
 The select tag and options
 ~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -452,10 +486,10 @@ To leverage time zone support in Rails, you have to ask our users what time zone
 
 There is also `time_zone_options_for_select` helper for a more manual (therefore more customizable) way of doing this. Read the API documentation to learn about the possible arguments for these two methods.
 
-Rails _used_ to have a `country_select` helper for choosing countries but this has been extracted to the http://github.com/rails/country_select/tree/master[country_select plugin]. When using this do be aware that the exclusion or inclusion of certain names from the list can be somewhat controversial (and was the reason this functionality was extracted from rails)
+Rails _used_ to have a `country_select` helper for choosing countries but this has been extracted to the http://github.com/rails/country_select/tree/master[country_select plugin]. When using this do be aware that the exclusion or inclusion of certain names from the list can be somewhat controversial (and was the reason this functionality was extracted from rails).
 
-Date and time select boxes
---------------------------
+Using Date and Time Form Helpers
+--------------------------------
 
 The date and time helpers differ from all the other form helpers in two important respects:
 
@@ -511,63 +545,7 @@ As a rule of thumb you should be using `date_select` when working with model obj
 
 NOTE: In many cases the built in date pickers are clumsy as they do not aid the user in working out the relationship between the date and the day of the week.
 
-Form builders
--------------
-
-As mentioned previously the object yielded by `form_for` and `fields_for` is an instance of FormBuilder (or a subclass thereof). Form builders encapsulate the notion of displaying a form elements for a single object. While you can of course write helpers for your forms in the usual way you can also subclass FormBuilder and add the helpers there. For example 
-
-----------
-<% form_for @person  do |f| %>
-  <%= text_field_with_label f, :first_name %>
-<% end %>
-----------
-can be replaced with 
-----------
-<% form_for @person, :builder => LabellingFormBuilder do |f| %>
-  <%= f.text_field :first_name %>
-<% end %>
-----------
-by defining a LabellingFormBuilder class similar to the following:
-
-[source, ruby]
--------
-class LabellingFormBuilder < FormBuilder
-  def text_field attribute, options={}
-    label(attribute) + text_field(attribute, options)
-  end
-end
--------
-If you reuse this frequently you could define a `labeled_form_for` helper that automatically applies the `:builder => LabellingFormBuilder` option.
-
-The form builder used also determines what happens when you do
-------
-<%= render :partial => f %>
-------
-If `f` is an instance of FormBuilder then this will render the 'form' partial, setting the partial's object to the form builder. If the form builder is of class LabellingFormBuilder then the 'labelling_form' partial would be rendered instead.
-
-Scoping out form controls with `fields_for`
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-`fields_for` creates a form builder in exactly the same way as `form_for` but doesn't create the actual `<form>` tags. It creates a scope around a specific model object like `form_for`, which is useful for specifying additional model objects in the same form. For example if you had a Person model with an associated ContactDetail model you could create a form for editing both like so:
--------------
-<% form_for @person do |person_form| %>
-  <%= person_form.text_field :name %>
-  <% fields_for @person.contact_detail do |contact_details_form| %>
-    <%= contact_details_form.text_field :phone_number %>
-  <% end %>
-<% end %>
--------------
-
-which produces the following output:
-
--------------
-<form action="/people/1" class="edit_person" id="edit_person_1" method="post">
-  <input id="person_name" name="person[name]" size="30" type="text" />  
-  <input id="contact_detail_phone_number" name="contact_detail[phone_number]" size="30" type="text" />
-</form>
--------------
-
-File Uploads
+Uploading Files
 --------------
 A common task is uploading some sort of file, whether it's a picture of a person or a CSV file containing data to process. The most important thing to remember with file uploads is that the form's encoding *MUST* be set to multipart/form-data. If you forget to do this the file will not be uploaded. This can be done by passing `:multi_part => true` as an HTML option. This means that in the case of `form_tag` it must be passed in the second options hash and in the case of `form_for` inside the `:html` hash.
 
@@ -605,13 +583,48 @@ Dealing with Ajax
 ~~~~~~~~~~~~~~~~~
 Unlike other forms making an asynchronous file upload form is not as simple as replacing `form_for` with `remote_form_for`. With an AJAX form the serialization is done by javascript running inside the browser and since javascript cannot read files from your hard drive the file cannot be uploaded. The most common workaround is to use an invisible iframe that serves as the target for the form submission.
 
-Parameter Names
----------------
+Customising Form Builders
+-------------------------
+
+As mentioned previously the object yielded by `form_for` and `fields_for` is an instance of FormBuilder (or a subclass thereof). Form builders encapsulate the notion of displaying a form elements for a single object. While you can of course write helpers for your forms in the usual way you can also subclass FormBuilder and add the helpers there. For example 
+
+----------
+<% form_for @person  do |f| %>
+  <%= text_field_with_label f, :first_name %>
+<% end %>
+----------
+can be replaced with 
+----------
+<% form_for @person, :builder => LabellingFormBuilder do |f| %>
+  <%= f.text_field :first_name %>
+<% end %>
+----------
+by defining a LabellingFormBuilder class similar to the following:
+
+[source, ruby]
+-------
+class LabellingFormBuilder < FormBuilder
+  def text_field attribute, options={}
+    label(attribute) + text_field(attribute, options)
+  end
+end
+-------
+If you reuse this frequently you could define a `labeled_form_for` helper that automatically applies the `:builder => LabellingFormBuilder` option.
+
+The form builder used also determines what happens when you do
+------
+<%= render :partial => f %>
+------
+If `f` is an instance of FormBuilder then this will render the 'form' partial, setting the partial's object to the form builder. If the form builder is of class LabellingFormBuilder then the 'labelling_form' partial would be rendered instead.
+
+Understanding Parameter Naming Conventions
+-----------------------------------------
+
 [[parameter_names]]
-As you've seen in the previous sections values from forms can appear either at the top level of the params hash or may appear nested in another hash. For example in a standard create
+As you've seen in the previous sections, values from forms can appear either at the top level of the params hash or may appear nested in another hash. For example in a standard create
 action for a Person model, `params[:model]` would usually be a hash of all the attributes for the person to create. The params hash can also contain arrays, arrays of hashes and so on.
 
-Fundamentally HTML forms don't know about any sort of structured data. All they know about is name-value pairs. Rails tacks some conventions onto parameter names which it uses to express some structure.
+Fundamentally HTML forms don't know about any sort of structured data, all they generate is name-value pairs. The arrays and hashes you see in your application are the result of some parameter naming conventions that Rails uses.
 
 [TIP]
 ========================
@@ -724,8 +737,8 @@ As a shortcut you can append [] to the name and omit the `:index` option. This i
 --------
 produces exactly the same output as the previous example.
 
-Complex forms
--------------
+Building Complex forms
+----------------------
 
 Many apps grow beyond simple forms editing a single object. For example when creating a Person instance you might want to allow the user to (on the same form) create multiple address records (home, work etc.). When later editing that person the user should be able to add, remove or amend addresses as necessary. While this guide has shown you all the pieces necessary to handle this, Rails does not yet have a standard end-to-end way of accomplishing this, but many have come up with viable approaches. These include:
 
diff --git a/railties/doc/guides/source/i18n.txt b/railties/doc/guides/source/i18n.txt
index ebbbbee8a9..2638807761 100644
--- a/railties/doc/guides/source/i18n.txt
+++ b/railties/doc/guides/source/i18n.txt
@@ -12,7 +12,7 @@ Internationalization is a complex problem. Natural languages differ in so many w
 * 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. ActiveRecord 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* -- eg. Active Record validation messages, time and date formats -- *has been internationalized*, so _localization_ of a Rails application means "over-riding" these defaults.
 
 === The overall architecture of the library
 
@@ -74,7 +74,7 @@ en:
   hello: "Hello world"
 -------------------------------------------------------
 
-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 ActiveRecord validation messages in the http://github.com/rails/rails/blob/master/activerecord/lib/active_record/locale/en.yml[+activerecord/lib/active_record/locale/en.yml+] file or time and date formats in the http://github.com/rails/rails/blob/master/activesupport/lib/active_support/locale/en.yml[+activesupport/lib/active_support/locale/en.yml+] file. You can use YAML or standard Ruby Hashes to store translations in the default (Simple) backend.
+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 http://github.com/rails/rails/blob/master/activerecord/lib/active_record/locale/en.yml[+activerecord/lib/active_record/locale/en.yml+] file or time and date formats in the http://github.com/rails/rails/blob/master/activesupport/lib/active_support/locale/en.yml[+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.
 
@@ -112,22 +112,115 @@ I18n.default_locale = :pt
 
 === Setting and passing the locale
 
-By default the I18n library will use :en (English) as a I18n.default_locale for looking up translations (if you do not specify a locale for a lookup).
+If you want to translate your Rails application to a *single language other than English* (the default locale), you can set I18n.default_locale to your locale in +environment.rb+ or an initializer as shown above, and it will persist through the requests.
 
-If you want to translate your Rails application to a single language other than English you can set I18n.default_locale to your locale. If you want to change the locale on a per-request basis though you can set it in a before_filter on the ApplicationController like this:
+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 http://en.wikipedia.org/wiki/Representational_State_Transfer[_RESTful_]. 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:
 
 [source, ruby]
 -------------------------------------------------------
 before_filter :set_locale
 def set_locale
-  # if this is nil then I18n.default_locale will be used
+  # if params[:locale] is nil then I18n.default_locale will be used
   I18n.locale = params[:locale] 
 end
 -------------------------------------------------------
 
-This will already work for URLs where you pass the locale as a query parameter as in example.com?locale=pt (which is what Google also does). 
+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.
+
+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.
+
+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 http://github.com/svenfuchs/i18n/commit/411f8fe7[this commit] and background at http://rails-i18n.org/wiki/pages/i18n-available_locales[Rails I18n Wiki].) 
+
+We have to include support for getting available locales manually in an initializer like this:
+
+[source, ruby]
+-------------------------------------------------------
+# config/initializers/available_locales.rb
+#
+# Get loaded locales conveniently
+# See http://rails-i18n.org/wiki/pages/i18n-available_locales
+module I18n
+  class << self
+    def available_locales; backend.available_locales; end
+  end
+  module Backend
+    class Simple
+      def available_locales; translations.keys.collect { |l| l.to_s }.sort; end
+    end
+  end
+end
+
+# You need to "force-initialize" loaded locales
+I18n.backend.send(:init_translations)
+
+AVAILABLE_LOCALES = I18n.backend.available_locales
+RAILS_DEFAULT_LOGGER.debug "* Loaded locales: #{AVAILABLE_LOCALES.inspect}"
+-------------------------------------------------------
+
+You can then wrap the constant for easy access in ApplicationController:
+
+[source, ruby]
+-------------------------------------------------------
+class ApplicationController < ActionController::Base
+  def available_locales; AVAILABLE_LOCALES; end
+end
+-------------------------------------------------------
+
+=== Setting locale from the domain name
 
-TIP: For other URL designs, see http://rails-i18n.org/wiki/pages/how-to-encode-the-current-locale-in-the-url[How to encode the current locale in the URL].
+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:
+
+* 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
+
+You can implement it like this in your ApplicationController:
+
+[source, ruby]
+-------------------------------------------------------
+before_filter :set_locale
+def set_locale
+  I18n.locale = extract_locale_from_uri
+end
+# Get locale from top-level domain or return nil if such locale is not available
+# You have to put something like:
+#   127.0.0.1 application.com
+#   127.0.0.1 application.it
+#   127.0.0.1 application.pl
+# in your /etc/hosts file to try this out locally
+def extract_locale_from_tld
+  parsed_locale = request.host.split('.').last
+  (available_locales.include? parsed_locale) ? parsed_locale  : nil
+end
+-------------------------------------------------------
+
+We can also set the locale from the _subdomain_ in very similar way:
+
+[source, ruby]
+-------------------------------------------------------
+# Get locale code from request subdomain (like http://it.application.local:3000)
+# You have to put something like:
+#   127.0.0.1 gr.application.local
+# in your /etc/hosts file to try this out locally
+def extract_locale_from_subdomain
+  parsed_locale = request.subdomains.first
+  (available_locales.include? parsed_locale) ? parsed_locale  : nil
+end
+-------------------------------------------------------
+
+=== Setting locale from the URL params
+
+* TODO : Based on *+default_url options+*, http://github.com/karmi/test_default_url_options/blob/master/app/controllers/application.rb#L22-26
+
+* TODO : Discussion of plugins (translate_routes and routing_filter)
+
+
+TIP: For setting locale from URL see http://rails-i18n.org/wiki/pages/how-to-encode-the-current-locale-in-the-url[How to encode the current locale in the URL] in the Rails i18n Wiki.
 
 Now you've initialized I18n support for your application and told it which locale should be used. With that in place you're now ready for the really interesting stuff.
 
@@ -199,7 +292,7 @@ pirate:
 
 There you go. Because you haven't changed the default_locale I18n will use English. Your application now shows:
 
-image:images/i18n/demo_translated_english.png[rails i18n demo translated to english]
+image:images/i18n/demo_translated_en.png[rails i18n demo translated to english]
 
 And when you change the URL to pass the pirate locale you get:
 
@@ -265,7 +358,7 @@ translate also takes a :scope option which can contain one or many additional ke
 I18n.t :invalid, :scope => [:active_record, :error_messages]
 -------------------------------------------------------
 
-This looks up the :invalid message in the ActiveRecord error messages.
+This looks up the :invalid message in the Active Record error messages.
 
 Additionally, both the key and scopes can be specified as dot separated keys as in:
 
@@ -314,7 +407,7 @@ I18n.t [:odd, :even], :scope => 'active_record.error_messages'
 # => ["must be odd", "must be even"]
 -------------------------------------------------------
 
-Also, a key can translate to a (potentially nested) hash as grouped translations. E.g. one can receive all ActiveRecord error messages as a Hash with:
+Also, a key can translate to a (potentially nested) hash as grouped translations. E.g. one can receive all Active Record error messages as a Hash with:
 
 [source, ruby]
 -------------------------------------------------------
@@ -445,7 +538,7 @@ I18n.t :short, :scope => [:date, :formats]
 
 Generally we recommend using YAML as a format for storing translations. There are cases though where you want to store Ruby lambdas as part of your locale data, e.g. for special date 
 
-=== Translations for ActiveRecord models
+=== Translations for Active Record models
 
 You can use the methods Model.human_name and Model.human_attribute_name(attribute) to transparently lookup translations for your model and attribute names.
 
@@ -467,7 +560,7 @@ Then User.human_name will return "Dude" and User.human_attribute_name(:login) wi
       
 ==== Error message scopes
 
-ActiveRecord validation error messages can also be translated easily. ActiveRecord gives you a couple of namespaces where you can place your message translations in order to provide different messages and translation for certain models, attributes and/or validations. It also transparently takes single table inheritance into account.
+Active Record validation error messages can also be translated easily. Active Record gives you a couple of namespaces where you can place your message translations in order to provide different messages and translation for certain models, attributes and/or validations. It also transparently takes single table inheritance into account.
 
 This gives you quite powerful means to flexibly adjust your messages to your application's needs.
 
@@ -480,7 +573,7 @@ class User < ActiveRecord::Base
 end
 -------------------------------------------------------
 
-The key for the error message in this case is :blank. ActiveRecord will lookup this key in the namespaces:
+The key for the error message in this case is :blank. Active Record will lookup this key in the namespaces:
 
 [source, ruby]
 -------------------------------------------------------
@@ -509,7 +602,7 @@ class Admin < User
 end
 -------------------------------------------------------
 
-Then ActiveRecord will look for messages in this order:
+Then Active Record will look for messages in this order:
 
 [source, ruby]
 -------------------------------------------------------
@@ -524,36 +617,41 @@ This way you can provide special translations for various error messages at diff
 
 ==== Error message interpolation
 
-The translated model name and translated attribute name are always available for interpolation. 
+The translated model name, translated attribute name, and value are always available for interpolation.
 
 So, for example, instead of the default error message "can not be blank" you could use the attribute name like this: "Please fill in your {{attribute}}".
 
-count and/or value are available where applicable. Count can be used for pluralization if present:
-
-|==================================================================================
-| validation                   | with option      | message         | interpolation
-| validates_confirmation_of    | -                | :confirmation   | -
-| validates_acceptance_of      | -                | :accepted       | -
-| validates_presence_of        | -                | :blank          | -
-| validates_length_of          | :within, :in     | :too_short      | count
-| validates_length_of          | :within, :in     | :too_long       | count
-| validates_length_of          | :is              | :wrong_length   | count
-| validates_length_of          | :minimum         | :too_short      | count
-| validates_length_of          | :maximum         | :too_long       | count
-| validates_uniqueness_of      | -                | :taken          | value
-| validates_format_of          | -                | :invalid        | value
-| validates_inclusion_of       | -                | :inclusion      | value
-| validates_exclusion_of       | -                | :exclusion      | value
-| validates_associated         | -                | :invalid        | value
-| validates_numericality_of    | -                | :not_a_number   | value
-| validates_numericality_of    | :odd             | :odd            | value
-| validates_numericality_of    | :even            | :even           | value
-|==================================================================================
-
-
-==== Translations for the ActiveRecord error_messages_for helper
-
-If you are using the ActiveRecord error_messages_for helper you will want to add translations for it. 
+count, where available, can be used for pluralization if present:
+
+|=====================================================================================================
+| validation                   | with option               | message                   | interpolation
+| validates_confirmation_of    | -                         | :confirmation             | -
+| validates_acceptance_of      | -                         | :accepted                 | -
+| validates_presence_of        | -                         | :blank                    | -
+| validates_length_of          | :within, :in              | :too_short                | count
+| validates_length_of          | :within, :in              | :too_long                 | count
+| validates_length_of          | :is                       | :wrong_length             | count
+| validates_length_of          | :minimum                  | :too_short                | count
+| validates_length_of          | :maximum                  | :too_long                 | count
+| validates_uniqueness_of      | -                         | :taken                    | -
+| validates_format_of          | -                         | :invalid                  | -
+| validates_inclusion_of       | -                         | :inclusion                | -
+| validates_exclusion_of       | -                         | :exclusion                | -
+| validates_associated         | -                         | :invalid                  | -
+| validates_numericality_of    | -                         | :not_a_number             | -
+| validates_numericality_of    | :greater_than             | :greater_than             | count
+| validates_numericality_of    | :greater_than_or_equal_to | :greater_than_or_equal_to | count
+| validates_numericality_of    | :equal_to                 | :equal_to                 | count
+| validates_numericality_of    | :less_than                | :less_than                | count
+| validates_numericality_of    | :less_than_or_equal_to    | :less_than_or_equal_to    | count
+| validates_numericality_of    | :odd                      | :odd                      | -
+| validates_numericality_of    | :even                     | :even                     | -
+|=====================================================================================================
+
+
+==== Translations for the Active Record error_messages_for helper
+
+If you are using the Active Record error_messages_for helper you will want to add translations for it. 
 
 Rails ships with the following translations:
 
@@ -570,11 +668,29 @@ en:
 -------------------------------------------------------
 
 
-=== Other translations and localizations
+=== Overview of other built-in methods that provide I18n support
+
+Rails uses fixed strings and other localizations, such as format strings and other format information in a couple of helpers. Here's a brief overview.
+
+==== ActionView helper methods
+
+* distance_of_time_in_words translates and pluralizes its result and interpolates the number of seconds, minutes, hours and so on. See http://github.com/rails/rails/blob/master/actionpack/lib/action_view/locale/en.yml#L51[datetime.distance_in_words] translations.
+
+* datetime_select and select_month use translated month names for populating the resulting select tag. See http://github.com/rails/rails/blob/master/activesupport/lib/active_support/locale/en.yml#L15[date.month_names] for translations. datetime_select also looks up the order option from http://github.com/rails/rails/blob/master/activesupport/lib/active_support/locale/en.yml#L18[date.order] (unless you pass the option explicitely). All date select helpers translate the prompt using the translations in the http://github.com/rails/rails/blob/master/actionpack/lib/action_view/locale/en.yml#L83[datetime.prompts] scope if applicable.
+
+* The number_to_currency, number_with_precision, number_to_percentage, number_with_delimiter and humber_to_human_size helpers use the number format settings located in the http://github.com/rails/rails/blob/master/actionpack/lib/action_view/locale/en.yml#L2[number] scope.
+
+==== Active Record methods
+
+* human_name and human_attribute_name use translations for model names and attribute names if available in the http://github.com/rails/rails/blob/master/activerecord/lib/active_record/locale/en.yml#L43[activerecord.models] scope. They also support translations for inherited class names (e.g. for use with STI) as explained above in "Error message scopes".
+
+* ActiveRecord::Errors#generate_message (which is used by Active Record validations but may also be used manually) uses human_name and human_attribute_name (see above). It also translates the error message and supports translations for inherited class names as explained above in "Error message scopes".
 
-Rails uses fixed strings and other localizations, such as format strings and other format information in a couple of helpers.
+* ActiveRecord::Errors#full_messages prepends the attribute name to the error message using a separator that will be looked up from http://github.com/rails/rails/blob/master/actionpack/lib/action_view/locale/en.yml#L91[activerecord.errors.format.separator] (and defaults to ' ').
 
-TODO list helpers and available keys
+==== ActiveSupport methods
+
+* Array#to_sentence uses format settings as given in the http://github.com/rails/rails/blob/master/activesupport/lib/active_support/locale/en.yml#L30[support.array] scope.
 
 
 == Customize your I18n setup
@@ -633,8 +749,39 @@ I18n.t :foo, :raise => true # always re-raises exceptions from the backend
 -------------------------------------------------------
 
 
+== Conclusion
+
+At this point you hopefully have a good overview about how I18n support in Ruby on Rails works and are ready to start translating your project.
+
+If you find anything missing or wrong in this guide please file a ticket on http://i18n.lighthouseapp.com/projects/14948-rails-i18n/overview[our issue tracker]. If you want to discuss certain portions or have questions please sign up to our http://groups.google.com/group/rails-i18n[mailinglist].
+
+
+== Contributing to Rails I18n
+
+I18n support in Ruby on Rails was introduced in the release 2.2 and is still evolving. The project follows the good Ruby on Rails development tradition of evolving solutions in plugins and real applications first and then cherry-picking the best bread of most widely useful features second for inclusion to the core.
+
+Thus we encourage everybody to experiment with new ideas and features in plugins or other libraries and make them available to the community. (Don't forget to announce your work on our http://groups.google.com/group/rails-i18n[mailinglist]!)
+
+If you find your own locale (language) missing from our http://github.com/svenfuchs/rails-i18n/tree/master/rails/locale[example translations data] repository for Ruby on Rails
+
+
 == Resources
 
+* http://rails-i18n.org[rails-i18n.org] - Homepage of the rails-i18n project. You can find lots of useful resources on the http://rails-i18n.org/wiki[wiki].
+* http://groups.google.com/group/rails-i18n[rails-i18n Google group] - The project's mailinglist. 
+* http://github.com/svenfuchs/rails-i18n/tree/master[Github: rails-i18n] - Code repository for the rails-i18n project. Most importantly you can find lots of http://github.com/svenfuchs/rails-i18n/tree/master/rails/locale[example translations] for Rails that should work for your application in most cases.
+* http://i18n.lighthouseapp.com/projects/14948-rails-i18n/overview[Lighthouse: rails-i18n] - Issue tracker for the rails-i18n project.
+* http://github.com/svenfuchs/i18n/tree/master[Github: i18n] - Code repository for the i18n gem.
+* http://i18n.lighthouseapp.com/projects/14947-ruby-i18n/overview[Lighthouse: i18n] - Issue tracker for the i18n gem.
+
+
+== Authors
+
+* Sven Fuchs[http://www.workingwithrails.com/person/9963-sven-fuchs] (initial author)
+* Karel Minarik[http://www.workingwithrails.com/person/7476-karel-mina-k]
+
+If you found this guide useful please consider recommending its authors on http://www.workingwithrails.com[workingwithrails].
+
 
 == Footnotes
 
@@ -644,9 +791,7 @@ I18n.t :foo, :raise => true # always re-raises exceptions from the backend
 
 [[[3]]] One of these reasons is that we don't want to any unnecessary load for applications that do not need any I18n capabilities, so we need to keep the I18n library as simple as possible for English. Another reason is that it is virtually impossible to implement a one-fits-all solution for all problems related to I18n for all existing languages. So a solution that allows us to exchange the entire implementation easily is appropriate anyway. This also makes it much easier to experiment with custom features and extensions.
 
-== Credits
-
-== NOTES
 
-How to contribute?
+== Changelog ==
 
+http://rails.lighthouseapp.com/projects/16213/tickets/23[Lighthouse ticket]
diff --git a/railties/doc/guides/source/index.txt b/railties/doc/guides/source/index.txt
index 9141a5292a..b32d8ef7b1 100644
--- a/railties/doc/guides/source/index.txt
+++ b/railties/doc/guides/source/index.txt
@@ -125,7 +125,7 @@ This guide covers how to build a plugin to extend the functionality of Rails.
 
 .link:i18n.html[The Rails Internationalization API]
 ***********************************************************
-CAUTION: still a basic draft
+CAUTION: link:http://rails.lighthouseapp.com/projects/16213/tickets/23[Lighthouse ticket]
 
 This guide introduces you to the basic concepts and features of the Rails I18n API and shows you how to localize your application.
 ***********************************************************