/README

  1== Welcome to Rails
  2
  3Rails is a web-application framework that includes everything needed to create
  4database-backed web applications according to the Model-View-Control pattern.
  5
  6This pattern splits the view (also called the presentation) into "dumb"
  7templates that are primarily responsible for inserting pre-built data in between
  8HTML tags. The model contains the "smart" domain objects (such as Account,
  9Product, Person, Post) that holds all the business logic and knows how to
 10persist themselves to a database. The controller handles the incoming requests
 11(such as Save New Account, Update Product, Show Post) by manipulating the model
 12and directing data to the view.
 13
 14In Rails, the model is handled by what's called an object-relational mapping
 15layer entitled Active Record. This layer allows you to present the data from
 16database rows as objects and embellish these data objects with business logic
 17methods. You can read more about Active Record in
 18link:files/vendor/rails/activerecord/README.html.
 19
 20The controller and view are handled by the Action Pack, which handles both
 21layers by its two parts: Action View and Action Controller. These two layers
 22are bundled in a single package due to their heavy interdependence. This is
 23unlike the relationship between the Active Record and Action Pack that is much
 24more separate. Each of these packages can be used independently outside of
 25Rails. You can read more about Action Pack in
 26link:files/vendor/rails/actionpack/README.html.
 27
 28
 29== Getting Started
 30
 311. At the command prompt, create a new Rails application:
 32       <tt>rails new myapp</tt> (where <tt>myapp</tt> is the application name)
 33
 342. Change directory to <tt>myapp</tt> and start the web server:
 35       <tt>cd myapp; rails server</tt> (run with --help for options)
 36
 373. Go to http://localhost:3000/ and you'll see:
 38       "Welcome aboard: You're riding Ruby on Rails!"
 39
 404. Follow the guidelines to start developing your application. You can find
 41the following resources handy:
 42
 43* The Getting Started Guide: http://guides.rubyonrails.org/getting_started.html
 44* Ruby on Rails Tutorial Book: http://www.railstutorial.org/
 45
 46
 47== Debugging Rails
 48
 49Sometimes your application goes wrong. Fortunately there are a lot of tools that
 50will help you debug it and get it back on the rails.
 51
 52First area to check is the application log files. Have "tail -f" commands
 53running on the server.log and development.log. Rails will automatically display
 54debugging and runtime information to these files. Debugging info will also be
 55shown in the browser on requests from 127.0.0.1.
 56
 57You can also log your own messages directly into the log file from your code
 58using the Ruby logger class from inside your controllers. Example:
 59
 60  class WeblogController < ActionController::Base
 61    def destroy
 62      @weblog = Weblog.find(params[:id])
 63      @weblog.destroy
 64      logger.info("#{Time.now} Destroyed Weblog ID ##{@weblog.id}!")
 65    end
 66  end
 67
 68The result will be a message in your log file along the lines of:
 69
 70  Mon Oct 08 14:22:29 +1000 2007 Destroyed Weblog ID #1!
 71
 72More information on how to use the logger is at http://www.ruby-doc.org/core/
 73
 74Also, Ruby documentation can be found at http://www.ruby-lang.org/. There are
 75several books available online as well:
 76
 77* Programming Ruby: http://www.ruby-doc.org/docs/ProgrammingRuby/ (Pickaxe)
 78* Learn to Program: http://pine.fm/LearnToProgram/ (a beginners guide)
 79
 80These two books will bring you up to speed on the Ruby language and also on
 81programming in general.
 82
 83
 84== Debugger
 85
 86Debugger support is available through the debugger command when you start your
 87Mongrel or WEBrick server with --debugger. This means that you can break out of
 88execution at any point in the code, investigate and change the model, and then,
 89resume execution! You need to install ruby-debug to run the server in debugging
 90mode. With gems, use <tt>sudo gem install ruby-debug</tt>. Example:
 91
 92  class WeblogController < ActionController::Base
 93    def index
 94      @posts = Post.all
 95      debugger
 96    end
 97  end
 98
 99So the controller will accept the action, run the first line, then present you
100with a IRB prompt in the server window. Here you can do things like:
101
102  >> @posts.inspect
103  => "[#<Post:0x14a6be8
104          @attributes={"title"=>nil, "body"=>nil, "id"=>"1"}>,
105       #<Post:0x14a6620
106          @attributes={"title"=>"Rails", "body"=>"Only ten..", "id"=>"2"}>]"
107  >> @posts.first.title = "hello from a debugger"
108  => "hello from a debugger"
109
110...and even better, you can examine how your runtime objects actually work:
111
112  >> f = @posts.first
113  => #<Post:0x13630c4 @attributes={"title"=>nil, "body"=>nil, "id"=>"1"}>
114  >> f.
115  Display all 152 possibilities? (y or n)
116
117Finally, when you're ready to resume execution, you can enter "cont".
118
119
120== Console
121
122The console is a Ruby shell, which allows you to interact with your
123application's domain model. Here you'll have all parts of the application
124configured, just like it is when the application is running. You can inspect
125domain models, change values, and save to the database. Starting the script
126without arguments will launch it in the development environment.
127
128To start the console, run <tt>rails console</tt> from the application
129directory.
130
131Options:
132
133* Passing the <tt>-s, --sandbox</tt> argument will rollback any modifications
134  made to the database.
135* Passing an environment name as an argument will load the corresponding
136  environment. Example: <tt>rails console production</tt>.
137
138To reload your controllers and models after launching the console run
139<tt>reload!</tt>
140
141More information about irb can be found at:
142link:http://www.rubycentral.org/pickaxe/irb.html
143
144
145== dbconsole
146
147You can go to the command line of your database directly through <tt>rails
148dbconsole</tt>. You would be connected to the database with the credentials
149defined in database.yml. Starting the script without arguments will connect you
150to the development database. Passing an argument will connect you to a different
151database, like <tt>rails dbconsole production</tt>. Currently works for MySQL,
152PostgreSQL and SQLite 3.
153
154== Description of Contents
155
156The default directory structure of a generated Ruby on Rails application:
157
158  |-- app
159  |   |-- assets
160  |       |-- images
161  |       |-- javascripts
162  |       `-- stylesheets
163  |   |-- controllers
164  |   |-- helpers
165  |   |-- mailers
166  |   |-- models
167  |   `-- views
168  |       `-- layouts
169  |-- config
170  |   |-- environments
171  |   |-- initializers
172  |   `-- locales
173  |-- db
174  |-- doc
175  |-- lib
176  |   `-- tasks
177  |-- log
178  |-- public
179  |-- script
180  |-- test
181  |   |-- fixtures
182  |   |-- functional
183  |   |-- integration
184  |   |-- performance
185  |   `-- unit
186  |-- tmp
187  |   |-- cache
188  |   |-- pids
189  |   |-- sessions
190  |   `-- sockets
191  `-- vendor
192      |-- assets
193          `-- stylesheets
194      `-- plugins
195
196app
197  Holds all the code that's specific to this particular application.
198
199app/assets
200  Contains subdirectories for images, stylesheets, and JavaScript files.
201
202app/controllers
203  Holds controllers that should be named like weblogs_controller.rb for
204  automated URL mapping. All controllers should descend from
205  ApplicationController which itself descends from ActionController::Base.
206
207app/models
208  Holds models that should be named like post.rb. Models descend from
209  ActiveRecord::Base by default.
210
211app/views
212  Holds the template files for the view that should be named like
213  weblogs/index.html.erb for the WeblogsController#index action. All views use
214  eRuby syntax by default.
215
216app/views/layouts
217  Holds the template files for layouts to be used with views. This models the
218  common header/footer method of wrapping views. In your views, define a layout
219  using the <tt>layout :default</tt> and create a file named default.html.erb.
220  Inside default.html.erb, call <% yield %> to render the view using this
221  layout.
222
223app/helpers
224  Holds view helpers that should be named like weblogs_helper.rb. These are
225  generated for you automatically when using generators for controllers.
226  Helpers can be used to wrap functionality for your views into methods.
227
228config
229  Configuration files for the Rails environment, the routing map, the database,
230  and other dependencies.
231
232db
233  Contains the database schema in schema.rb. db/migrate contains all the
234  sequence of Migrations for your schema.
235
236doc
237  This directory is where your application documentation will be stored when
238  generated using <tt>rake doc:app</tt>
239
240lib
241  Application specific libraries. Basically, any kind of custom code that
242  doesn't belong under controllers, models, or helpers. This directory is in
243  the load path.
244
245public
246  The directory available for the web server. Also contains the dispatchers and the
247  default HTML files. This should be set as the DOCUMENT_ROOT of your web
248  server.
249
250script
251  Helper scripts for automation and generation.
252
253test
254  Unit and functional tests along with fixtures. When using the rails generate
255  command, template test files will be generated for you and placed in this
256  directory.
257
258vendor
259  External libraries that the application depends on. Also includes the plugins
260  subdirectory. If the app has frozen rails, those gems also go here, under
261  vendor/rails/. This directory is in the load path.