184 lines
7.2 KiB
Plaintext
184 lines
7.2 KiB
Plaintext
== 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. Start the web server: <tt>ruby script/server</tt> (run with --help for options)
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2. Go to http://localhost:3000/ and get "Welcome aboard: You’re riding the Rails!"
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3. Follow the guidelines to start developing your application
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== Web servers
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Rails uses the built-in web server in Ruby called WEBrick by default, so you don't
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have to install or configure anything to play around.
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If you have lighttpd installed, though, it'll be used instead when running script/server.
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It's considerably faster than WEBrick and 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 WEBrick). 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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If you want something that's halfway between WEBrick and lighttpd, we heartily recommend
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Mongrel. It's a Ruby-based web server with a C-component (so it requires compilation) that
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also works very well with Windows. See more at http://mongrel.rubyforge.org/.
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But of course its also possible to run Rails with the premiere open source web server Apache.
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To get decent performance, though, you'll need to install FastCGI. For Apache 1.3, you want
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to use mod_fastcgi. For Apache 2.0+, you want to use mod_fcgid.
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See http://wiki.rubyonrails.com/rails/pages/FastCGI for more information on FastCGI.
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== Example for Apache conf
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<VirtualHost *:80>
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ServerName rails
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DocumentRoot /path/application/public/
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ErrorLog /path/application/log/server.log
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<Directory /path/application/public/>
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Options ExecCGI FollowSymLinks
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AllowOverride all
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Allow from all
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Order allow,deny
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</Directory>
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</VirtualHost>
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NOTE: Be sure that CGIs can be executed in that directory as well. So ExecCGI
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should be on and ".cgi" should respond. All requests from 127.0.0.1 go
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through CGI, so no Apache restart is necessary for changes. All other requests
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go through FCGI (or mod_ruby), which requires a restart to show changes.
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== Debugging Rails
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Have "tail -f" commands running on both the server.log, production.log, and
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test.log files. Rails will automatically display debugging and runtime
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information to these files. Debugging info will also be shown in the browser
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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 script/console.
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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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== 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 weblog_controller.rb for
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automated URL mapping. All controllers should descend from
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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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weblog/index.rhtml for the WeblogController#index action. All views use eRuby
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syntax. This directory can also be used to keep stylesheets, images, and so on
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that can be symlinked to public.
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app/helpers
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Holds view helpers that should be named like weblog_helper.rb.
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app/apis
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Holds API classes for web services.
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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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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.
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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.
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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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