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

1 files changed, 163 insertions, 0 deletions

diff --git a/actionpack/lib/action_controller/base.rb b/actionpack/lib/action_controller/base.rb
index 9dfffced75..165bf089c0 100644
--- a/actionpack/lib/action_controller/base.rb
+++ b/actionpack/lib/action_controller/base.rb
@@ -1,6 +1,169 @@
 require "action_controller/log_subscriber"
 
 module ActionController
+  # Action Controllers are the core of a web request in \Rails. They are made up of one or more actions that are executed
+  # on request and then either render a template or redirect to another action. An action is defined as a public method
+  # on the controller, which will automatically be made accessible to the web-server through \Rails Routes.
+  #
+  # By default, only the ApplicationController in a \Rails application inherits from <tt>ActionController::Base</tt>. All other
+  # controllers in turn inherit from ApplicationController. This gives you one class to configure things such as
+  # request forgery protection and filtering of sensitive request parameters.
+  #
+  # A sample controller could look like this:
+  #
+  #   class PostsController < ApplicationController
+  #     def index
+  #       @posts = Post.all
+  #     end
+  #
+  #     def create
+  #       @post = Post.create params[:post]
+  #       redirect_to posts_path
+  #     end
+  #   end
+  #
+  # Actions, by default, render a template in the <tt>app/views</tt> directory corresponding to the name of the controller and action
+  # after executing code in the action. For example, the +index+ action of the PostsController would render the
+  # template <tt>app/views/posts/index.erb</tt> by default after populating the <tt>@posts</tt> instance variable.
+  #
+  # Unlike index, the create action will not render a template. After performing its main purpose (creating a
+  # new post), it initiates a redirect instead. This redirect works by returning an external
+  # "302 Moved" HTTP response that takes the user to the index action.
+  #
+  # These two methods represent the two basic action archetypes used in Action Controllers. Get-and-show and do-and-redirect.
+  # Most actions are variations of these themes.
+  #
+  # == Requests
+  #
+  # For every request, the router determines the value of the +controller+ and +action+ keys. These determine which controller
+  # and action are called. The remaining request parameters, the session (if one is available), and the full request with
+  # all the HTTP headers are made available to the action through accessor methods. Then the action is performed.
+  #
+  # The full request object is available via the request accessor and is primarily used to query for HTTP headers:
+  #
+  #   def server_ip
+  #     location = request.env["SERVER_ADDR"]
+  #     render :text => "This server hosted at #{location}"
+  #   end
+  #
+  # == Parameters
+  #
+  # All request parameters, whether they come from a GET or POST request, or from the URL, are available through the params method
+  # which returns a hash. For example, an action that was performed through <tt>/posts?category=All&limit=5</tt> will include
+  # <tt>{ "category" => "All", "limit" => 5 }</tt> in params.
+  #
+  # It's also possible to construct multi-dimensional parameter hashes by specifying keys using brackets, such as:
+  #
+  #   <input type="text" name="post[name]" value="david">
+  #   <input type="text" name="post[address]" value="hyacintvej">
+  #
+  # A request stemming from a form holding these inputs will include <tt>{ "post" => { "name" => "david", "address" => "hyacintvej" } }</tt>.
+  # If the address input had been named "post[address][street]", the params would have included
+  # <tt>{ "post" => { "address" => { "street" => "hyacintvej" } } }</tt>. There's no limit to the depth of the nesting.
+  #
+  # == Sessions
+  #
+  # Sessions allows you to store objects in between requests. This is useful for objects that are not yet ready to be persisted,
+  # such as a Signup object constructed in a multi-paged process, or objects that don't change much and are needed all the time, such
+  # as a User object for a system that requires login. The session should not be used, however, as a cache for objects where it's likely
+  # they could be changed unknowingly. It's usually too much work to keep it all synchronized -- something databases already excel at.
+  #
+  # You can place objects in the session by using the <tt>session</tt> method, which accesses a hash:
+  #
+  #   session[:person] = Person.authenticate(user_name, password)
+  #
+  # And retrieved again through the same hash:
+  #
+  #   Hello #{session[:person]}
+  #
+  # For removing objects from the session, you can either assign a single key to +nil+:
+  #
+  #   # removes :person from session
+  #   session[:person] = nil
+  #
+  # or you can remove the entire session with +reset_session+.
+  #
+  # Sessions are stored by default in a browser cookie that's cryptographically signed, but unencrypted.
+  # This prevents the user from tampering with the session but also allows him to see its contents.
+  #
+  # Do not put secret information in cookie-based sessions!
+  #
+  # Other options for session storage:
+  #
+  # * ActiveRecord::SessionStore - Sessions are stored in your database, which works better than PStore with multiple app servers and,
+  #   unlike CookieStore, hides your session contents from the user. To use ActiveRecord::SessionStore, set
+  #
+  #     config.action_controller.session_store = :active_record_store
+  #
+  #   in your <tt>config/environment.rb</tt> and run <tt>rake db:sessions:create</tt>.
+  #
+  # == Responses
+  #
+  # Each action results in a response, which holds the headers and document to be sent to the user's browser. The actual response
+  # object is generated automatically through the use of renders and redirects and requires no user intervention.
+  #
+  # == Renders
+  #
+  # Action Controller sends content to the user by using one of five rendering methods. The most versatile and common is the rendering
+  # of a template. Included in the Action Pack is the Action View, which enables rendering of ERb templates. It's automatically configured.
+  # The controller passes objects to the view by assigning instance variables:
+  #
+  #   def show
+  #     @post = Post.find(params[:id])
+  #   end
+  #
+  # Which are then automatically available to the view:
+  #
+  #   Title: <%= @post.title %>
+  #
+  # You don't have to rely on the automated rendering. Especially actions that could result in the rendering of different templates will use
+  # the manual rendering methods:
+  #
+  #   def search
+  #     @results = Search.find(params[:query])
+  #     case @results
+  #       when 0 then render :action => "no_results"
+  #       when 1 then render :action => "show"
+  #       when 2..10 then render :action => "show_many"
+  #     end
+  #   end
+  #
+  # Read more about writing ERb and Builder templates in ActionView::Base.
+  #
+  # == Redirects
+  #
+  # Redirects are used to move from one action to another. For example, after a <tt>create</tt> action, which stores a blog entry to a database,
+  # we might like to show the user the new entry. Because we're following good DRY principles (Don't Repeat Yourself), we're going to reuse (and redirect to)
+  # a <tt>show</tt> action that we'll assume has already been created. The code might look like this:
+  #
+  #   def create
+  #     @entry = Entry.new(params[:entry])
+  #     if @entry.save
+  #       # The entry was saved correctly, redirect to show
+  #       redirect_to :action => 'show', :id => @entry.id
+  #     else
+  #       # things didn't go so well, do something else
+  #     end
+  #   end
+  #
+  # In this case, after saving our new entry to the database, the user is redirected to the <tt>show</tt> method which is then executed.
+  #
+  # == Calling multiple redirects or renders
+  #
+  # An action may contain only a single render or a single redirect. Attempting to try to do either again will result in a DoubleRenderError:
+  #
+  #   def do_something
+  #     redirect_to :action => "elsewhere"
+  #     render :action => "overthere" # raises DoubleRenderError
+  #   end
+  #
+  # If you need to redirect on the condition of something, then be sure to add "and return" to halt execution.
+  #
+  #   def do_something
+  #     redirect_to(:action => "elsewhere") and return if monkeys.nil?
+  #     render :action => "overthere" # won't be called if monkeys is nil
+  #   end
+  #
   class Base < Metal
     abstract!