[7b7d827] | 1 | == Welcome to Rails |
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| 2 | |
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| 3 | Rails is a web-application and persistence framework that includes everything |
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| 4 | needed to create database-backed web-applications according to the |
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| 5 | Model-View-Control pattern of separation. This pattern splits the view (also |
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| 6 | called the presentation) into "dumb" templates that are primarily responsible |
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| 7 | for inserting pre-built data in between HTML tags. The model contains the |
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| 8 | "smart" domain objects (such as Account, Product, Person, Post) that holds all |
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| 9 | the business logic and knows how to persist themselves to a database. The |
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| 10 | controller handles the incoming requests (such as Save New Account, Update |
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| 11 | Product, Show Post) by manipulating the model and directing data to the view. |
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| 12 | |
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| 13 | In Rails, the model is handled by what's called an object-relational mapping |
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| 14 | layer entitled Active Record. This layer allows you to present the data from |
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| 15 | database rows as objects and embellish these data objects with business logic |
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| 16 | methods. You can read more about Active Record in |
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| 17 | link:files/vendor/rails/activerecord/README.html. |
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| 18 | |
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| 19 | The controller and view are handled by the Action Pack, which handles both |
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| 20 | layers by its two parts: Action View and Action Controller. These two layers |
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| 21 | are bundled in a single package due to their heavy interdependence. This is |
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| 22 | unlike the relationship between the Active Record and Action Pack that is much |
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| 23 | more separate. Each of these packages can be used independently outside of |
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| 24 | Rails. You can read more about Action Pack in |
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| 25 | link:files/vendor/rails/actionpack/README.html. |
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| 26 | |
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| 27 | |
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| 28 | == Getting started |
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| 29 | |
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| 30 | 1. At the command prompt, start a new rails application using the rails command |
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| 31 | and your application name. Ex: rails myapp |
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| 32 | (If you've downloaded rails in a complete tgz or zip, this step is already done) |
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| 33 | 2. Change directory into myapp and start the web server: <tt>script/server</tt> (run with --help for options) |
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| 34 | 3. Go to http://localhost:3000/ and get "Welcome aboard: Youâre riding the Rails!" |
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| 35 | 4. Follow the guidelines to start developing your application |
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| 36 | |
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| 37 | |
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| 38 | == Web Servers |
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| 39 | |
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| 40 | By default, Rails will try to use Mongrel and lighttpd if they are installed, otherwise |
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| 41 | Rails will use the WEBrick, the webserver that ships with Ruby. When you run script/server, |
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| 42 | Rails will check if Mongrel exists, then lighttpd and finally fall back to WEBrick. This ensures |
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| 43 | that you can always get up and running quickly. |
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| 44 | |
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| 45 | Mongrel is a Ruby-based webserver with a C-component (which requires compilation) that is |
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| 46 | suitable for development and deployment of Rails applications. If you have Ruby Gems installed, |
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| 47 | getting up and running with mongrel is as easy as: <tt>gem install mongrel</tt>. |
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| 48 | More info at: http://mongrel.rubyforge.org |
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| 49 | |
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| 50 | If Mongrel is not installed, Rails will look for lighttpd. It's considerably faster than |
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| 51 | Mongrel and WEBrick and also suited for production use, but requires additional |
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| 52 | installation and currently only works well on OS X/Unix (Windows users are encouraged |
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| 53 | to start with Mongrel). We recommend version 1.4.11 and higher. You can download it from |
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| 54 | http://www.lighttpd.net. |
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| 55 | |
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| 56 | And finally, if neither Mongrel or lighttpd are installed, Rails will use the built-in Ruby |
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| 57 | web server, WEBrick. WEBrick is a small Ruby web server suitable for development, but not |
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| 58 | for production. |
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| 59 | |
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| 60 | But of course its also possible to run Rails on any platform that supports FCGI. |
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| 61 | Apache, LiteSpeed, IIS are just a few. For more information on FCGI, |
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| 62 | please visit: http://wiki.rubyonrails.com/rails/pages/FastCGI |
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| 63 | |
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| 64 | |
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| 65 | == Debugging Rails |
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| 66 | |
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| 67 | Have "tail -f" commands running on the server.log and development.log. Rails will |
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| 68 | automatically display debugging and runtime information to these files. Debugging |
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| 69 | info will also be shown in the browser on requests from 127.0.0.1. |
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| 70 | |
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| 71 | |
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| 72 | == Breakpoints |
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| 73 | |
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| 74 | Breakpoint support is available through the script/breakpointer client. This |
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| 75 | means that you can break out of execution at any point in the code, investigate |
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| 76 | and change the model, AND then resume execution! Example: |
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| 77 | |
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| 78 | class WeblogController < ActionController::Base |
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| 79 | def index |
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| 80 | @posts = Post.find(:all) |
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| 81 | breakpoint "Breaking out from the list" |
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| 82 | end |
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| 83 | end |
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| 84 | |
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| 85 | So the controller will accept the action, run the first line, then present you |
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| 86 | with a IRB prompt in the breakpointer window. Here you can do things like: |
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| 87 | |
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| 88 | Executing breakpoint "Breaking out from the list" at .../webrick_server.rb:16 in 'breakpoint' |
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| 89 | |
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| 90 | >> @posts.inspect |
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| 91 | => "[#<Post:0x14a6be8 @attributes={\"title\"=>nil, \"body\"=>nil, \"id\"=>\"1\"}>, |
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| 92 | #<Post:0x14a6620 @attributes={\"title\"=>\"Rails you know!\", \"body\"=>\"Only ten..\", \"id\"=>\"2\"}>]" |
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| 93 | >> @posts.first.title = "hello from a breakpoint" |
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| 94 | => "hello from a breakpoint" |
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| 95 | |
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| 96 | ...and even better is that you can examine how your runtime objects actually work: |
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| 97 | |
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| 98 | >> f = @posts.first |
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| 99 | => #<Post:0x13630c4 @attributes={"title"=>nil, "body"=>nil, "id"=>"1"}> |
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| 100 | >> f. |
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| 101 | Display all 152 possibilities? (y or n) |
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| 102 | |
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| 103 | Finally, when you're ready to resume execution, you press CTRL-D |
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| 104 | |
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| 105 | |
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| 106 | == Console |
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| 107 | |
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| 108 | You can interact with the domain model by starting the console through <tt>script/console</tt>. |
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| 109 | Here you'll have all parts of the application configured, just like it is when the |
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| 110 | application is running. You can inspect domain models, change values, and save to the |
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| 111 | database. Starting the script without arguments will launch it in the development environment. |
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| 112 | Passing an argument will specify a different environment, like <tt>script/console production</tt>. |
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| 113 | |
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| 114 | To reload your controllers and models after launching the console run <tt>reload!</tt> |
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| 115 | |
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| 116 | To reload your controllers and models after launching the console run <tt>reload!</tt> |
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| 117 | |
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| 118 | |
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| 119 | |
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| 120 | == Description of contents |
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| 121 | |
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| 122 | app |
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| 123 | Holds all the code that's specific to this particular application. |
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| 124 | |
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| 125 | app/controllers |
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| 126 | Holds controllers that should be named like weblogs_controller.rb for |
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| 127 | automated URL mapping. All controllers should descend from ApplicationController |
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| 128 | which itself descends from ActionController::Base. |
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| 129 | |
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| 130 | app/models |
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| 131 | Holds models that should be named like post.rb. |
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| 132 | Most models will descend from ActiveRecord::Base. |
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| 133 | |
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| 134 | app/views |
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| 135 | Holds the template files for the view that should be named like |
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| 136 | weblogs/index.rhtml for the WeblogsController#index action. All views use eRuby |
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| 137 | syntax. |
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| 138 | |
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| 139 | app/views/layouts |
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| 140 | Holds the template files for layouts to be used with views. This models the common |
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| 141 | header/footer method of wrapping views. In your views, define a layout using the |
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| 142 | <tt>layout :default</tt> and create a file named default.rhtml. Inside default.rhtml, |
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| 143 | call <% yield %> to render the view using this layout. |
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| 144 | |
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| 145 | app/helpers |
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| 146 | Holds view helpers that should be named like weblogs_helper.rb. These are generated |
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| 147 | for you automatically when using script/generate for controllers. Helpers can be used to |
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| 148 | wrap functionality for your views into methods. |
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| 149 | |
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| 150 | config |
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| 151 | Configuration files for the Rails environment, the routing map, the database, and other dependencies. |
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| 152 | |
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| 153 | components |
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| 154 | Self-contained mini-applications that can bundle together controllers, models, and views. |
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| 155 | |
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| 156 | db |
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| 157 | Contains the database schema in schema.rb. db/migrate contains all |
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| 158 | the sequence of Migrations for your schema. |
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| 159 | |
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| 160 | doc |
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| 161 | This directory is where your application documentation will be stored when generated |
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| 162 | using <tt>rake doc:app</tt> |
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| 163 | |
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| 164 | lib |
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| 165 | Application specific libraries. Basically, any kind of custom code that doesn't |
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| 166 | belong under controllers, models, or helpers. This directory is in the load path. |
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| 167 | |
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| 168 | public |
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| 169 | The directory available for the web server. Contains subdirectories for images, stylesheets, |
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| 170 | and javascripts. Also contains the dispatchers and the default HTML files. This should be |
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| 171 | set as the DOCUMENT_ROOT of your web server. |
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| 172 | |
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| 173 | script |
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| 174 | Helper scripts for automation and generation. |
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| 175 | |
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| 176 | test |
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| 177 | Unit and functional tests along with fixtures. When using the script/generate scripts, template |
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| 178 | test files will be generated for you and placed in this directory. |
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| 179 | |
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| 180 | vendor |
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| 181 | External libraries that the application depends on. Also includes the plugins subdirectory. |
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| 182 | This directory is in the load path. |
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