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== Welcome to Rails |
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Rails is a web-application and persistence framework that includes everything |
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needed to create database-backed web-applications according to the |
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Model-View-Control pattern of separation. This pattern splits the view (also |
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called the presentation) into "dumb" templates that are primarily responsible |
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for inserting pre-built data in between HTML tags. The model contains the |
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"smart" domain objects (such as Account, Product, Person, Post) that holds all |
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the business logic and knows how to persist themselves to a database. The |
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controller handles the incoming requests (such as Save New Account, Update |
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Product, Show Post) by manipulating the model and directing data to the view. |
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In Rails, the model is handled by what's called an object-relational mapping |
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layer entitled Active Record. This layer allows you to present the data from |
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database rows as objects and embellish these data objects with business logic |
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methods. You can read more about Active Record in |
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link:files/vendor/rails/activerecord/README.html. |
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The controller and view are handled by the Action Pack, which handles both |
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layers by its two parts: Action View and Action Controller. These two layers |
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are bundled in a single package due to their heavy interdependence. This is |
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unlike the relationship between the Active Record and Action Pack that is much |
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more separate. Each of these packages can be used independently outside of |
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Rails. You can read more about Action Pack in |
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link:files/vendor/rails/actionpack/README.html. |
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== Getting started |
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1. At the command prompt, start a new rails application using the rails command |
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and your application name. Ex: rails myapp |
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(If you've downloaded rails in a complete tgz or zip, this step is already done) |
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2. Change directory into myapp and start the web server: <tt>script/server</tt> (run with --help for options) |
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3. Go to http://localhost:3000/ and get "Welcome aboard: You’re riding the Rails!" |
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4. Follow the guidelines to start developing your application |
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== Web Servers |
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By default, Rails will try to use Mongrel and lighttpd if they are installed, otherwise |
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Rails will use the WEBrick, the webserver that ships with Ruby. When you run script/server, |
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Rails will check if Mongrel exists, then lighttpd and finally fall back to WEBrick. This ensures |
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that you can always get up and running quickly. |
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Mongrel is a Ruby-based webserver with a C-component (which requires compilation) that is |
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suitable for development and deployment of Rails applications. If you have Ruby Gems installed, |
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getting up and running with mongrel is as easy as: <tt>gem install mongrel</tt>. |
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More info at: http://mongrel.rubyforge.org |
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If Mongrel is not installed, Rails will look for lighttpd. It's considerably faster than |
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Mongrel and WEBrick and also suited for production use, but requires additional |
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installation and currently only works well on OS X/Unix (Windows users are encouraged |
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to start with Mongrel). We recommend version 1.4.11 and higher. You can download it from |
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http://www.lighttpd.net. |
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And finally, if neither Mongrel or lighttpd are installed, Rails will use the built-in Ruby |
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web server, WEBrick. WEBrick is a small Ruby web server suitable for development, but not |
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for production. |
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But of course its also possible to run Rails on any platform that supports FCGI. |
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Apache, LiteSpeed, IIS are just a few. For more information on FCGI, |
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please visit: http://wiki.rubyonrails.com/rails/pages/FastCGI |
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== Debugging Rails |
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Have "tail -f" commands running on the server.log and development.log. Rails will |
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automatically display debugging and runtime information to these files. Debugging |
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info will also be shown in the browser on requests from 127.0.0.1. |
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== Breakpoints |
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Breakpoint support is available through the script/breakpointer client. This |
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means that you can break out of execution at any point in the code, investigate |
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and change the model, AND then resume execution! Example: |
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class WeblogController < ActionController::Base |
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def index |
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@posts = Post.find(:all) |
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breakpoint "Breaking out from the list" |
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end |
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end |
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So the controller will accept the action, run the first line, then present you |
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with a IRB prompt in the breakpointer window. Here you can do things like: |
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Executing breakpoint "Breaking out from the list" at .../webrick_server.rb:16 in 'breakpoint' |
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>> @posts.inspect |
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=> "[#<Post:0x14a6be8 @attributes={\"title\"=>nil, \"body\"=>nil, \"id\"=>\"1\"}>, |
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#<Post:0x14a6620 @attributes={\"title\"=>\"Rails you know!\", \"body\"=>\"Only ten..\", \"id\"=>\"2\"}>]" |
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>> @posts.first.title = "hello from a breakpoint" |
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=> "hello from a breakpoint" |
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...and even better is that you can examine how your runtime objects actually work: |
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>> f = @posts.first |
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=> #<Post:0x13630c4 @attributes={"title"=>nil, "body"=>nil, "id"=>"1"}> |
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>> f. |
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Display all 152 possibilities? (y or n) |
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Finally, when you're ready to resume execution, you press CTRL-D |
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== Console |
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You can interact with the domain model by starting the console through <tt>script/console</tt>. |
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Here you'll have all parts of the application configured, just like it is when the |
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application is running. You can inspect domain models, change values, and save to the |
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database. Starting the script without arguments will launch it in the development environment. |
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Passing an argument will specify a different environment, like <tt>script/console production</tt>. |
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To reload your controllers and models after launching the console run <tt>reload!</tt> |
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To reload your controllers and models after launching the console run <tt>reload!</tt> |
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== Description of contents |
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app |
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Holds all the code that's specific to this particular application. |
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app/controllers |
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Holds controllers that should be named like weblogs_controller.rb for |
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automated URL mapping. All controllers should descend from ApplicationController |
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which itself descends from ActionController::Base. |
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app/models |
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Holds models that should be named like post.rb. |
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Most models will descend from ActiveRecord::Base. |
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app/views |
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Holds the template files for the view that should be named like |
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weblogs/index.rhtml for the WeblogsController#index action. All views use eRuby |
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syntax. |
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app/views/layouts |
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Holds the template files for layouts to be used with views. This models the common |
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header/footer method of wrapping views. In your views, define a layout using the |
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<tt>layout :default</tt> and create a file named default.rhtml. Inside default.rhtml, |
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call <% yield %> to render the view using this layout. |
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app/helpers |
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Holds view helpers that should be named like weblogs_helper.rb. These are generated |
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for you automatically when using script/generate for controllers. Helpers can be used to |
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wrap functionality for your views into methods. |
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config |
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Configuration files for the Rails environment, the routing map, the database, and other dependencies. |
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components |
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Self-contained mini-applications that can bundle together controllers, models, and views. |
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db |
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Contains the database schema in schema.rb. db/migrate contains all |
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the sequence of Migrations for your schema. |
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doc |
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This directory is where your application documentation will be stored when generated |
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using <tt>rake doc:app</tt> |
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lib |
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Application specific libraries. Basically, any kind of custom code that doesn't |
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belong under controllers, models, or helpers. This directory is in the load path. |
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public |
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The directory available for the web server. Contains subdirectories for images, stylesheets, |
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and javascripts. Also contains the dispatchers and the default HTML files. This should be |
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set as the DOCUMENT_ROOT of your web server. |
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script |
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Helper scripts for automation and generation. |
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test |
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Unit and functional tests along with fixtures. When using the script/generate scripts, template |
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test files will be generated for you and placed in this directory. |
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vendor |
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External libraries that the application depends on. Also includes the plugins subdirectory. |
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This directory is in the load path. |
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