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5c7f91f @wycats Generated the Rails 3 application
authored
1 == Welcome to Rails
2
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.
5
6 This pattern splits the view (also called the presentation) into "dumb"
7 templates that are primarily responsible for inserting pre-built data in between
8 HTML tags. The model contains the "smart" domain objects (such as Account,
9 Product, Person, Post) that holds all the business logic and knows how to
10 persist themselves to a database. The controller handles the incoming requests
11 (such as Save New Account, Update Product, Show Post) by manipulating the model
12 and directing data to the view.
13
14 In Rails, the model is handled by what's called an object-relational mapping
15 layer entitled Active Record. This layer allows you to present the data from
16 database rows as objects and embellish these data objects with business logic
17 methods. You can read more about Active Record in
18 link:files/vendor/rails/activerecord/README.html.
19
20 The controller and view are handled by the Action Pack, which handles both
21 layers by its two parts: Action View and Action Controller. These two layers
22 are bundled in a single package due to their heavy interdependence. This is
23 unlike the relationship between the Active Record and Action Pack that is much
24 more separate. Each of these packages can be used independently outside of
25 Rails. You can read more about Action Pack in
26 link:files/vendor/rails/actionpack/README.html.
27
28
29 == Getting Started
30
31 1. At the command prompt, create a new Rails application:
32 <tt>rails new myapp</tt> (where <tt>myapp</tt> is the application name)
33
34 2. Change directory to <tt>myapp</tt> and start the web server:
35 <tt>cd myapp; rails server</tt> (run with --help for options)
36
37 3. Go to http://localhost:3000/ and you'll see:
38 "Welcome aboard: You're riding Ruby on Rails!"
39
40 4. Follow the guidelines to start developing your application. You can find
41 the 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
49 Sometimes your application goes wrong. Fortunately there are a lot of tools that
50 will help you debug it and get it back on the rails.
51
52 First area to check is the application log files. Have "tail -f" commands
53 running on the server.log and development.log. Rails will automatically display
54 debugging and runtime information to these files. Debugging info will also be
55 shown in the browser on requests from 127.0.0.1.
56
57 You can also log your own messages directly into the log file from your code
58 using 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
68 The 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
72 More information on how to use the logger is at http://www.ruby-doc.org/core/
73
74 Also, Ruby documentation can be found at http://www.ruby-lang.org/. There are
75 several 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
80 These two books will bring you up to speed on the Ruby language and also on
81 programming in general.
82
83
84 == Debugger
85
86 Debugger support is available through the debugger command when you start your
87 Mongrel or WEBrick server with --debugger. This means that you can break out of
88 execution at any point in the code, investigate and change the model, and then,
89 resume execution! You need to install ruby-debug to run the server in debugging
90 mode. 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
99 So the controller will accept the action, run the first line, then present you
100 with 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
117 Finally, when you're ready to resume execution, you can enter "cont".
118
119
120 == Console
121
122 The console is a Ruby shell, which allows you to interact with your
123 application's domain model. Here you'll have all parts of the application
124 configured, just like it is when the application is running. You can inspect
125 domain models, change values, and save to the database. Starting the script
126 without arguments will launch it in the development environment.
127
128 To start the console, run <tt>rails console</tt> from the application
129 directory.
130
131 Options:
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
138 To reload your controllers and models after launching the console run
139 <tt>reload!</tt>
140
141 More information about irb can be found at:
142 link:http://www.rubycentral.org/pickaxe/irb.html
143
144
145 == dbconsole
146
147 You can go to the command line of your database directly through <tt>rails
148 dbconsole</tt>. You would be connected to the database with the credentials
149 defined in database.yml. Starting the script without arguments will connect you
150 to the development database. Passing an argument will connect you to a different
151 database, like <tt>rails dbconsole production</tt>. Currently works for MySQL,
152 PostgreSQL and SQLite 3.
153
154 == Description of Contents
155
156 The default directory structure of a generated Ruby on Rails application:
157
158 |-- app
159 | |-- controllers
160 | |-- helpers
161 | |-- mailers
162 | |-- models
163 | `-- views
164 | `-- layouts
165 |-- config
166 | |-- environments
167 | |-- initializers
168 | `-- locales
169 |-- db
170 |-- doc
171 |-- lib
172 | `-- tasks
173 |-- log
174 |-- public
175 | |-- images
176 | |-- javascripts
177 | `-- stylesheets
178 |-- script
179 |-- test
180 | |-- fixtures
181 | |-- functional
182 | |-- integration
183 | |-- performance
184 | `-- unit
185 |-- tmp
186 | |-- cache
187 | |-- pids
188 | |-- sessions
189 | `-- sockets
190 `-- vendor
191 `-- plugins
192
193 app
194 Holds all the code that's specific to this particular application.
195
196 app/controllers
197 Holds controllers that should be named like weblogs_controller.rb for
198 automated URL mapping. All controllers should descend from
199 ApplicationController which itself descends from ActionController::Base.
200
201 app/models
202 Holds models that should be named like post.rb. Models descend from
203 ActiveRecord::Base by default.
204
205 app/views
206 Holds the template files for the view that should be named like
207 weblogs/index.html.erb for the WeblogsController#index action. All views use
208 eRuby syntax by default.
209
210 app/views/layouts
211 Holds the template files for layouts to be used with views. This models the
212 common header/footer method of wrapping views. In your views, define a layout
213 using the <tt>layout :default</tt> and create a file named default.html.erb.
214 Inside default.html.erb, call <% yield %> to render the view using this
215 layout.
216
217 app/helpers
218 Holds view helpers that should be named like weblogs_helper.rb. These are
219 generated for you automatically when using generators for controllers.
220 Helpers can be used to wrap functionality for your views into methods.
221
222 config
223 Configuration files for the Rails environment, the routing map, the database,
224 and other dependencies.
225
226 db
227 Contains the database schema in schema.rb. db/migrate contains all the
228 sequence of Migrations for your schema.
229
230 doc
231 This directory is where your application documentation will be stored when
232 generated using <tt>rake doc:app</tt>
233
234 lib
235 Application specific libraries. Basically, any kind of custom code that
236 doesn't belong under controllers, models, or helpers. This directory is in
237 the load path.
238
239 public
240 The directory available for the web server. Contains subdirectories for
241 images, stylesheets, and javascripts. Also contains the dispatchers and the
242 default HTML files. This should be set as the DOCUMENT_ROOT of your web
243 server.
244
245 script
246 Helper scripts for automation and generation.
247
248 test
249 Unit and functional tests along with fixtures. When using the rails generate
250 command, template test files will be generated for you and placed in this
251 directory.
252
253 vendor
254 External libraries that the application depends on. Also includes the plugins
255 subdirectory. If the app has frozen rails, those gems also go here, under
256 vendor/rails/. This directory is in the load path.
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