== Welcome to RailsRails is a web-application framework that includes everything needed to createdatabase-backed web applications according to the Model-View-Control pattern.This pattern splits the view (also called the presentation) into "dumb"templates that are primarily responsible for inserting pre-built data in betweenHTML tags. The model contains the "smart" domain objects (such as Account,Product, Person, Post) that holds all the business logic and knows how topersist themselves to a database. The controller handles the incoming requests(such as Save New Account, Update Product, Show Post) by manipulating the modeland directing data to the view.In Rails, the model is handled by what's called an object-relational mappinglayer entitled Active Record. This layer allows you to present the data fromdatabase rows as objects and embellish these data objects with business logicmethods. You can read more about Active Record inlink:files/vendor/rails/activerecord/README.html.The controller and view are handled by the Action Pack, which handles bothlayers by its two parts: Action View and Action Controller. These two layersare bundled in a single package due to their heavy interdependence. This isunlike the relationship between the Active Record and Action Pack that is muchmore separate. Each of these packages can be used independently outside ofRails. You can read more about Action Pack inlink:files/vendor/rails/actionpack/README.html.== Getting Started1. At the command prompt, create a new Rails application:       <tt>rails new myapp</tt> (where <tt>myapp</tt> is the application name)2. Change directory to <tt>myapp</tt> and start the web server:       <tt>cd myapp; rails server</tt> (run with --help for options)3. Go to http://localhost:3000/ and you'll see:       "Welcome aboard: You're riding Ruby on Rails!"4. Follow the guidelines to start developing your application. You can findthe following resources handy:* The Getting Started Guide:http://guides.rubyonrails.org/getting_started.html* Ruby on Rails Tutorial Book:http://www.railstutorial.org/== Debugging RailsSometimes your application goes wrong. Fortunately there are a lot of tools thatwill help you debug it and get it back on the rails.First area to check is the application log files. Have "tail -f" commandsrunning on the server.log and development.log. Rails will automatically displaydebugging and runtime information to these files. Debugging info will also beshown in the browser on requests from 127.0.0.1.You can also log your own messages directly into the log file from your codeusing the Ruby logger class from inside your controllers. Example:  class WeblogController < ActionController::Base    def destroy      @weblog = Weblog.find(params[:id])      @weblog.destroy      logger.info("#{Time.now} Destroyed Weblog ID ##{@weblog.id}!")    end  endThe result will be a message in your log file along the lines of:  Mon Oct 08 14:22:29 +1000 2007 Destroyed Weblog ID #1!More information on how to use the logger is athttp://www.ruby-doc.org/core/Also, Ruby documentation can be found athttp://www.ruby-lang.org/. There areseveral books available online as well:* Programming Ruby:http://www.ruby-doc.org/docs/ProgrammingRuby/ (Pickaxe)* Learn to Program:http://pine.fm/LearnToProgram/ (a beginners guide)These two books will bring you up to speed on the Ruby language and also onprogramming in general.== DebuggerDebugger support is available through the debugger command when you start yourMongrel or WEBrick server with --debugger. This means that you can break out ofexecution at any point in the code, investigate and change the model, and then,resume execution! You need to install ruby-debug to run the server in debuggingmode. With gems, use <tt>sudo gem install ruby-debug</tt>. Example:  class WeblogController < ActionController::Base    def index      @posts = Post.all      debugger    end  endSo the controller will accept the action, run the first line, then present youwith a IRB prompt in the server window. Here you can do things like:  >> @posts.inspect  => "[#<Post:0x14a6be8          @attributes={"title"=>nil, "body"=>nil, "id"=>"1"}>,       #<Post:0x14a6620          @attributes={"title"=>"Rails", "body"=>"Only ten..", "id"=>"2"}>]"  >> @posts.first.title = "hello from a debugger"  => "hello from a debugger"...and even better, you can examine how your runtime objects actually work:  >> f = @posts.first  => #<Post:0x13630c4 @attributes={"title"=>nil, "body"=>nil, "id"=>"1"}>  >> f.  Display all 152 possibilities? (y or n)Finally, when you're ready to resume execution, you can enter "cont".== ConsoleThe console is a Ruby shell, which allows you to interact with yourapplication's domain model. Here you'll have all parts of the applicationconfigured, just like it is when the application is running. You can inspectdomain models, change values, and save to the database. Starting the scriptwithout arguments will launch it in the development environment.To start the console, run <tt>rails console</tt> from the applicationdirectory.Options:* Passing the <tt>-s, --sandbox</tt> argument will rollback any modifications  made to the database.* Passing an environment name as an argument will load the corresponding  environment. Example: <tt>rails console production</tt>.To reload your controllers and models after launching the console run<tt>reload!</tt>More information about irb can be found at:link:http://www.rubycentral.org/pickaxe/irb.html== dbconsoleYou can go to the command line of your database directly through <tt>railsdbconsole</tt>. You would be connected to the database with the credentialsdefined in database.yml. Starting the script without arguments will connect youto the development database. Passing an argument will connect you to a differentdatabase, like <tt>rails dbconsole production</tt>. Currently works for MySQL,PostgreSQL and SQLite 3.== Description of ContentsThe default directory structure of a generated Ruby on Rails application:  |-- app  |   |-- assets  |       |-- images  |       |-- javascripts  |       `-- stylesheets  |   |-- controllers  |   |-- helpers  |   |-- mailers  |   |-- models  |   `-- views  |       `-- layouts  |-- config  |   |-- environments  |   |-- initializers  |   `-- locales  |-- db  |-- doc  |-- lib  |   `-- tasks  |-- log  |-- public  |-- script  |-- test  |   |-- fixtures  |   |-- functional  |   |-- integration  |   |-- performance  |   `-- unit  |-- tmp  |   |-- cache  |   |-- pids  |   |-- sessions  |   `-- sockets  `-- vendor      |-- assets          `-- stylesheets      `-- pluginsapp  Holds all the code that's specific to this particular application.app/assets  Contains subdirectories for images, stylesheets, and JavaScript files.app/controllers  Holds controllers that should be named like weblogs_controller.rb for  automated URL mapping. All controllers should descend from  ApplicationController which itself descends from ActionController::Base.app/models  Holds models that should be named like post.rb. Models descend from  ActiveRecord::Base by default.app/views  Holds the template files for the view that should be named like  weblogs/index.html.erb for the WeblogsController#index action. All views use  eRuby syntax by default.app/views/layouts  Holds the template files for layouts to be used with views. This models the  common header/footer method of wrapping views. In your views, define a layout  using the <tt>layout :default</tt> and create a file named default.html.erb.  Inside default.html.erb, call <% yield %> to render the view using this  layout.app/helpers  Holds view helpers that should be named like weblogs_helper.rb. These are  generated for you automatically when using generators for controllers.  Helpers can be used to wrap functionality for your views into methods.config  Configuration files for the Rails environment, the routing map, the database,  and other dependencies.db  Contains the database schema in schema.rb. db/migrate contains all the  sequence of Migrations for your schema.doc  This directory is where your application documentation will be stored when  generated using <tt>rake doc:app</tt>lib  Application specific libraries. Basically, any kind of custom code that  doesn't belong under controllers, models, or helpers. This directory is in  the load path.public  The directory available for the web server. Also contains the dispatchers and the  default HTML files. This should be set as the DOCUMENT_ROOT of your web  server.script  Helper scripts for automation and generation.test  Unit and functional tests along with fixtures. When using the rails generate  command, template test files will be generated for you and placed in this  directory.vendor  External libraries that the application depends on. Also includes the plugins  subdirectory. If the app has frozen rails, those gems also go here, under  vendor/rails/. This directory is in the load path.