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be0c96e @dhh First init
1 == Welcome to Rails
3 Rails is a web-application framework that includes everything needed to create
4 database-backed web applications according to the Model-View-Control pattern.
6 This pattern splits the view (also called the presentation) into "dumb" templates
7 that are primarily responsible for inserting pre-built data in between HTML tags.
8 The model contains the "smart" domain objects (such as Account, Product, Person,
9 Post) that holds all the business logic and knows how to persist themselves to
10 a database. The controller handles the incoming requests (such as Save New Account,
11 Update Product, Show Post) by manipulating the model and directing data to the view.
13 In Rails, the model is handled by what's called an object-relational mapping
14 layer entitled Active Record. This layer allows you to present the data from
15 database rows as objects and embellish these data objects with business logic
16 methods. You can read more about Active Record in
17 link:files/vendor/rails/activerecord/README.html.
19 The controller and view are handled by the Action Pack, which handles both
20 layers by its two parts: Action View and Action Controller. These two layers
21 are bundled in a single package due to their heavy interdependence. This is
22 unlike the relationship between the Active Record and Action Pack that is much
23 more separate. Each of these packages can be used independently outside of
24 Rails. You can read more about Action Pack in
25 link:files/vendor/rails/actionpack/README.html.
28 == Getting Started
30 1. At the command prompt, start a new Rails application using the <tt>rails</tt> command
31 and your application name. Ex: rails myapp
32 2. Change directory into myapp and start the web server: <tt>script/server</tt> (run with --help for options)
33 3. Go to http://localhost:3000/ and get "Welcome aboard: You're riding the Rails!"
34 4. Follow the guidelines to start developing your application
37 == Web Servers
39 By default, Rails will try to use Mongrel and lighttpd if they are installed, otherwise
40 Rails will use WEBrick, the webserver that ships with Ruby. When you run script/server,
41 Rails will check if Mongrel exists, then lighttpd and finally fall back to WEBrick. This ensures
42 that you can always get up and running quickly.
44 Mongrel is a Ruby-based webserver with a C component (which requires compilation) that is
45 suitable for development and deployment of Rails applications. If you have Ruby Gems installed,
46 getting up and running with mongrel is as easy as: <tt>gem install mongrel</tt>.
47 More info at:
49 If Mongrel is not installed, Rails will look for lighttpd. It's considerably faster than
50 Mongrel and WEBrick and also suited for production use, but requires additional
51 installation and currently only works well on OS X/Unix (Windows users are encouraged
52 to start with Mongrel). We recommend version 1.4.11 and higher. You can download it from
55 And finally, if neither Mongrel or lighttpd are installed, Rails will use the built-in Ruby
56 web server, WEBrick. WEBrick is a small Ruby web server suitable for development, but not
57 for production.
59 But of course its also possible to run Rails on any platform that supports FCGI.
60 Apache, LiteSpeed, IIS are just a few. For more information on FCGI,
61 please visit:
64 == Apache .htaccess example
66 # General Apache options
67 AddHandler fastcgi-script .fcgi
68 AddHandler cgi-script .cgi
69 Options +FollowSymLinks +ExecCGI
71 # If you don't want Rails to look in certain directories,
72 # use the following rewrite rules so that Apache won't rewrite certain requests
73 #
74 # Example:
75 # RewriteCond %{REQUEST_URI} ^/notrails.*
76 # RewriteRule .* - [L]
78 # Redirect all requests not available on the filesystem to Rails
79 # By default the cgi dispatcher is used which is very slow
80 #
81 # For better performance replace the dispatcher with the fastcgi one
82 #
83 # Example:
84 # RewriteRule ^(.*)$ dispatch.fcgi [QSA,L]
85 RewriteEngine On
87 # If your Rails application is accessed via an Alias directive,
88 # then you MUST also set the RewriteBase in this htaccess file.
89 #
90 # Example:
91 # Alias /myrailsapp /path/to/myrailsapp/public
92 # RewriteBase /myrailsapp
94 RewriteRule ^$ index.html [QSA]
95 RewriteRule ^([^.]+)$ $1.html [QSA]
96 RewriteCond %{REQUEST_FILENAME} !-f
97 RewriteRule ^(.*)$ dispatch.cgi [QSA,L]
99 # In case Rails experiences terminal errors
100 # Instead of displaying this message you can supply a file here which will be rendered instead
101 #
102 # Example:
103 # ErrorDocument 500 /500.html
105 ErrorDocument 500 "<h2>Application error</h2>Rails application failed to start properly"
108 == Debugging Rails
110 Sometimes your application goes wrong. Fortunately there are a lot of tools that
111 will help you debug it and get it back on the rails.
113 First area to check is the application log files. Have "tail -f" commands running
114 on the server.log and development.log. Rails will automatically display debugging
115 and runtime information to these files. Debugging info will also be shown in the
116 browser on requests from
118 You can also log your own messages directly into the log file from your code using
119 the Ruby logger class from inside your controllers. Example:
121 class WeblogController < ActionController::Base
122 def destroy
123 @weblog = Weblog.find(params[:id])
124 @weblog.destroy
125"#{} Destroyed Weblog ID ##{}!")
126 end
127 end
129 The result will be a message in your log file along the lines of:
131 Mon Oct 08 14:22:29 +1000 2007 Destroyed Weblog ID #1
133 More information on how to use the logger is at
135 Also, Ruby documentation can be found at including:
137 * The Learning Ruby (Pickaxe) Book:
138 * Learn to Program: (a beginners guide)
140 These two online (and free) books will bring you up to speed on the Ruby language
141 and also on programming in general.
144 == Debugger
146 Debugger support is available through the debugger command when you start your Mongrel or
147 Webrick server with --debugger. This means that you can break out of execution at any point
148 in the code, investigate and change the model, AND then resume execution!
149 You need to install ruby-debug to run the server in debugging mode. With gems, use 'gem install ruby-debug'
150 Example:
152 class WeblogController < ActionController::Base
153 def index
154 @posts = Post.find(:all)
155 debugger
156 end
157 end
159 So the controller will accept the action, run the first line, then present you
160 with a IRB prompt in the server window. Here you can do things like:
162 >> @posts.inspect
163 => "[#<Post:0x14a6be8 @attributes={\"title\"=>nil, \"body\"=>nil, \"id\"=>\"1\"}>,
164 #<Post:0x14a6620 @attributes={\"title\"=>\"Rails you know!\", \"body\"=>\"Only ten..\", \"id\"=>\"2\"}>]"
165 >> @posts.first.title = "hello from a debugger"
166 => "hello from a debugger"
168 ...and even better is that you can examine how your runtime objects actually work:
170 >> f = @posts.first
171 => #<Post:0x13630c4 @attributes={"title"=>nil, "body"=>nil, "id"=>"1"}>
172 >> f.
173 Display all 152 possibilities? (y or n)
175 Finally, when you're ready to resume execution, you enter "cont"
178 == Console
180 You can interact with the domain model by starting the console through <tt>script/console</tt>.
181 Here you'll have all parts of the application configured, just like it is when the
182 application is running. You can inspect domain models, change values, and save to the
183 database. Starting the script without arguments will launch it in the development environment.
184 Passing an argument will specify a different environment, like <tt>script/console production</tt>.
186 To reload your controllers and models after launching the console run <tt>reload!</tt>
188 == dbconsole
190 You can go to the command line of your database directly through <tt>script/dbconsole</tt>.
191 You would be connected to the database with the credentials defined in database.yml.
192 Starting the script without arguments will connect you to the development database. Passing an
193 argument will connect you to a different database, like <tt>script/dbconsole production</tt>.
194 Currently works for mysql, postgresql and sqlite.
196 == Description of Contents
198 app
199 Holds all the code that's specific to this particular application.
201 app/controllers
202 Holds controllers that should be named like weblogs_controller.rb for
203 automated URL mapping. All controllers should descend from ApplicationController
204 which itself descends from ActionController::Base.
206 app/models
207 Holds models that should be named like post.rb.
208 Most models will descend from ActiveRecord::Base.
210 app/views
211 Holds the template files for the view that should be named like
212 weblogs/index.html.erb for the WeblogsController#index action. All views use eRuby
213 syntax.
215 app/views/layouts
216 Holds the template files for layouts to be used with views. This models the common
217 header/footer method of wrapping views. In your views, define a layout using the
218 <tt>layout :default</tt> and create a file named default.html.erb. Inside default.html.erb,
219 call <% yield %> to render the view using this layout.
221 app/helpers
222 Holds view helpers that should be named like weblogs_helper.rb. These are generated
223 for you automatically when using script/generate for controllers. Helpers can be used to
224 wrap functionality for your views into methods.
226 config
227 Configuration files for the Rails environment, the routing map, the database, and other dependencies.
229 db
230 Contains the database schema in schema.rb. db/migrate contains all
231 the sequence of Migrations for your schema.
233 doc
234 This directory is where your application documentation will be stored when generated
235 using <tt>rake doc:app</tt>
237 lib
238 Application specific libraries. Basically, any kind of custom code that doesn't
239 belong under controllers, models, or helpers. This directory is in the load path.
241 public
242 The directory available for the web server. Contains subdirectories for images, stylesheets,
243 and javascripts. Also contains the dispatchers and the default HTML files. This should be
244 set as the DOCUMENT_ROOT of your web server.
246 script
247 Helper scripts for automation and generation.
249 test
250 Unit and functional tests along with fixtures. When using the script/generate scripts, template
251 test files will be generated for you and placed in this directory.
253 vendor
254 External libraries that the application depends on. Also includes the plugins subdirectory.
255 If the app has frozen rails, those gems also go here, under vendor/rails/.
256 This directory is in the load path.
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