README

   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" 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.
  12
  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.
  18
  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.
  26
  27
  28 == Getting Started
  29
  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
  35
  36
  37 == Web Servers
  38
  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.
  43
  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: http://mongrel.rubyforge.org
  48
  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
  53 http://www.lighttpd.net.
  54
  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.
  58
  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: http://wiki.rubyonrails.com/rails/pages/FastCGI
  62
  63
  64 == Apache .htaccess example
  65
  66 # General Apache options
  67 AddHandler fastcgi-script .fcgi
  68 AddHandler cgi-script .cgi
  69 Options +FollowSymLinks +ExecCGI
  70
  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]
  77
  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
  86
  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
  93
  94 RewriteRule ^$ index.html [QSA]
  95 RewriteRule ^([^.]+)$ $1.html [QSA]
  96 RewriteCond %{REQUEST_FILENAME} !-f
  97 RewriteRule ^(.*)$ dispatch.cgi [QSA,L]
  98
  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
 104
 105 ErrorDocument 500 "<h2>Application error</h2>Rails application failed to start properly"
 106
 107
 108 == Debugging Rails
 109
 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.
 112
 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 127.0.0.1.
 117
 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:
 120
 121   class WeblogController < ActionController::Base
 122     def destroy
 123       @weblog = Weblog.find(params[:id])
 124       @weblog.destroy
 125       logger.info("#{Time.now} Destroyed Weblog ID ##{@weblog.id}!")
 126     end
 127   end
 128
 129 The result will be a message in your log file along the lines of:
 130
 131   Mon Oct 08 14:22:29 +1000 2007 Destroyed Weblog ID #1
 132
 133 More information on how to use the logger is at http://www.ruby-doc.org/core/
 134
 135 Also, Ruby documentation can be found at http://www.ruby-lang.org/ including:
 136
 137 * The Learning Ruby (Pickaxe) Book: http://www.ruby-doc.org/docs/ProgrammingRuby/
 138 * Learn to Program: http://pine.fm/LearnToProgram/  (a beginners guide)
 139
 140 These two online (and free) books will bring you up to speed on the Ruby language
 141 and also on programming in general.
 142
 143
 144 == Debugger
 145
 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:
 151
 152   class WeblogController < ActionController::Base
 153     def index
 154       @posts = Post.find(:all)
 155       debugger
 156     end
 157   end
 158
 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:
 161
 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"
 167
 168 ...and even better is that you can examine how your runtime objects actually work:
 169
 170   >> f = @posts.first
 171   => #<Post:0x13630c4 @attributes={"title"=>nil, "body"=>nil, "id"=>"1"}>
 172   >> f.
 173   Display all 152 possibilities? (y or n)
 174
 175 Finally, when you're ready to resume execution, you enter "cont"
 176
 177
 178 == Console
 179
 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>.
 185
 186 To reload your controllers and models after launching the console run <tt>reload!</tt>
 187
 188 == dbconsole
 189
 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.
 195
 196 == Description of Contents
 197
 198 app
 199   Holds all the code that's specific to this particular application.
 200
 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.
 205
 206 app/models
 207   Holds models that should be named like post.rb.
 208   Most models will descend from ActiveRecord::Base.
 209
 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.
 214
 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.
 220
 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.
 225
 226 config
 227   Configuration files for the Rails environment, the routing map, the database, and other dependencies.
 228
 229 db
 230   Contains the database schema in schema.rb.  db/migrate contains all
 231   the sequence of Migrations for your schema.
 232
 233 doc
 234   This directory is where your application documentation will be stored when generated
 235   using <tt>rake doc:app</tt>
 236
 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.
 240
 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.
 245
 246 script
 247   Helper scripts for automation and generation.
 248
 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.
 252
 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.