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- == Welcome to Rails
- Rails is a web-application framework that includes everything needed to create
- database-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 between
- HTML tags. The model contains the "smart" domain objects (such as Account,
- Product, Person, Post) that holds all the business logic and knows how to
- persist themselves to a database. The controller handles the incoming requests
- (such as Save New Account, Update Product, Show Post) by manipulating the model
- and directing data to the view.
- In Rails, the model is handled by what's called an object-relational mapping
- layer entitled Active Record. This layer allows you to present the data from
- database rows as objects and embellish these data objects with business logic
- methods. You can read more about Active Record in
- link:files/vendor/rails/activerecord/README.html.
- The controller and view are handled by the Action Pack, which handles both
- layers by its two parts: Action View and Action Controller. These two layers
- are bundled in a single package due to their heavy interdependence. This is
- unlike the relationship between the Active Record and Action Pack that is much
- more separate. Each of these packages can be used independently outside of
- Rails. You can read more about Action Pack in
- link:files/vendor/rails/actionpack/README.html.
- == Getting Started
- 1. 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 find
- the following resources handy:
- * The Getting Started Guide: http://guides.rubyonrails.org/getting_started.html
- * Ruby on Rails Tutorial Book: http://www.railstutorial.org/
- == Debugging Rails
- Sometimes your application goes wrong. Fortunately there are a lot of tools that
- will help you debug it and get it back on the rails.
- First area to check is the application log files. Have "tail -f" commands
- running on the server.log and development.log. Rails will automatically display
- debugging and runtime information to these files. Debugging info will also be
- shown in the browser on requests from 127.0.0.1.
- You can also log your own messages directly into the log file from your code
- using 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
- end
- The 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 at http://www.ruby-doc.org/core/
- Also, Ruby documentation can be found at http://www.ruby-lang.org/. There are
- several 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 on
- programming in general.
- == Debugger
- Debugger support is available through the debugger command when you start your
- Mongrel or WEBrick server with --debugger. This means that you can break out of
- execution 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 debugging
- mode. With gems, use <tt>sudo gem install ruby-debug</tt>. Example:
- class WeblogController < ActionController::Base
- def index
- @posts = Post.all
- debugger
- end
- end
- So the controller will accept the action, run the first line, then present you
- with 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".
- == Console
- The console is a Ruby shell, which allows you to interact with your
- application's domain model. Here you'll have all parts of the application
- configured, just like it is when the application is running. You can inspect
- domain models, change values, and save to the database. Starting the script
- without arguments will launch it in the development environment.
- To start the console, run <tt>rails console</tt> from the application
- directory.
- 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
- == dbconsole
- You can go to the command line of your database directly through <tt>rails
- dbconsole</tt>. You would be connected to the database with the credentials
- defined in database.yml. Starting the script without arguments will connect you
- to the development database. Passing an argument will connect you to a different
- database, like <tt>rails dbconsole production</tt>. Currently works for MySQL,
- PostgreSQL and SQLite 3.
- == Description of Contents
- The 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
- `-- plugins
- app
- 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.
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