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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, start a new Rails application using the <tt>rails</tt> command
- and your application name. Ex: rails myapp
- 2. Change directory into myapp and start the web server: <tt>script/server</tt> (run with --help for options)
- 3. Go to http://localhost:3000/ and get "Welcome aboard: You're riding the Rails!"
- 4. Follow the guidelines to start developing your application
- == Web Servers
- By default, Rails will try to use Mongrel if it's are installed when started with script/server, otherwise Rails will use WEBrick, the webserver that ships with Ruby. But you can also use Rails
- with a variety of other web servers.
- Mongrel is a Ruby-based webserver with a C component (which requires compilation) that is
- suitable for development and deployment of Rails applications. If you have Ruby Gems installed,
- getting up and running with mongrel is as easy as: <tt>gem install mongrel</tt>.
- More info at: http://mongrel.rubyforge.org
- Say other Ruby web servers like Thin and Ebb or regular web servers like Apache or LiteSpeed or
- Lighttpd or IIS. The Ruby web servers are run through Rack and the latter can either be setup to use
- FCGI or proxy to a pack of Mongrels/Thin/Ebb servers.
- == Apache .htaccess example for FCGI/CGI
- # General Apache options
- AddHandler fastcgi-script .fcgi
- AddHandler cgi-script .cgi
- Options +FollowSymLinks +ExecCGI
- # If you don't want Rails to look in certain directories,
- # use the following rewrite rules so that Apache won't rewrite certain requests
- #
- # Example:
- # RewriteCond %{REQUEST_URI} ^/notrails.*
- # RewriteRule .* - [L]
- # Redirect all requests not available on the filesystem to Rails
- # By default the cgi dispatcher is used which is very slow
- #
- # For better performance replace the dispatcher with the fastcgi one
- #
- # Example:
- # RewriteRule ^(.*)$ dispatch.fcgi [QSA,L]
- RewriteEngine On
- # If your Rails application is accessed via an Alias directive,
- # then you MUST also set the RewriteBase in this htaccess file.
- #
- # Example:
- # Alias /myrailsapp /path/to/myrailsapp/public
- # RewriteBase /myrailsapp
- RewriteRule ^$ index.html [QSA]
- RewriteRule ^([^.]+)$ $1.html [QSA]
- RewriteCond %{REQUEST_FILENAME} !-f
- RewriteRule ^(.*)$ dispatch.cgi [QSA,L]
- # In case Rails experiences terminal errors
- # Instead of displaying this message you can supply a file here which will be rendered instead
- #
- # Example:
- # ErrorDocument 500 /500.html
- ErrorDocument 500 "<h2>Application error</h2>Rails application failed to start properly"
- == 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/ including:
- * The Learning Ruby (Pickaxe) Book: http://www.ruby-doc.org/docs/ProgrammingRuby/
- * Learn to Program: http://pine.fm/LearnToProgram/ (a beginners guide)
- These two online (and free) 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 'gem install ruby-debug'
- Example:
- class WeblogController < ActionController::Base
- def index
- @posts = Post.find(: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 you know!\", \"body\"=>\"Only ten..\", \"id\"=>\"2\"}>]"
- >> @posts.first.title = "hello from a debugger"
- => "hello from a debugger"
- ...and even better is that 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 enter "cont"
- == Console
- You can interact with the domain model by starting the console through <tt>script/console</tt>.
- 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.
- Passing an argument will specify a different environment, like <tt>script/console production</tt>.
- To reload your controllers and models after launching the console run <tt>reload!</tt>
- == dbconsole
- You can go to the command line of your database directly through <tt>script/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>script/dbconsole production</tt>.
- Currently works for mysql, postgresql and sqlite.
- == Description of Contents
- app
- Holds all the code that's specific to this particular application.
- 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.
- Most models will descend from ActiveRecord::Base.
- 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.
- 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 script/generate 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. Contains subdirectories for images, stylesheets,
- and javascripts. 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 script/generate scripts, 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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