| 1 | == Welcome to Rails |
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| 2 | |
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| 3 | Rails is a web-application framework that includes everything needed to create |
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| 4 | database-backed web applications according to the Model-View-Control pattern. |
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| 5 | |
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| 6 | This pattern splits the view (also called the presentation) into "dumb" templates |
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| 7 | that are primarily responsible for inserting pre-built data in between HTML tags. |
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| 8 | The model contains the "smart" domain objects (such as Account, Product, Person, |
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| 9 | Post) that holds all the business logic and knows how to persist themselves to |
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| 10 | a database. The controller handles the incoming requests (such as Save New Account, |
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| 11 | Update 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 <tt>rails</tt> command |
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| 31 | and your application name. Ex: rails myapp |
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| 32 | 2. Change directory into myapp and start the web server: <tt>script/server</tt> (run with --help for options) |
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| 33 | 3. Go to http://localhost:3000/ and get "Welcome aboard: You're riding the Rails!" |
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| 34 | 4. Follow the guidelines to start developing your application |
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| 35 | |
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| 36 | |
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| 37 | == Web Servers |
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| 38 | |
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| 39 | By default, Rails will try to use Mongrel if it's are installed when started with script/server, otherwise Rails will use WEBrick, the webserver that ships with Ruby. But you can also use Rails |
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| 40 | with a variety of other web servers. |
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| 41 | |
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| 42 | Mongrel is a Ruby-based webserver with a C component (which requires compilation) that is |
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| 43 | suitable for development and deployment of Rails applications. If you have Ruby Gems installed, |
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| 44 | getting up and running with mongrel is as easy as: <tt>gem install mongrel</tt>. |
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| 45 | More info at: http://mongrel.rubyforge.org |
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| 46 | |
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| 47 | Say other Ruby web servers like Thin and Ebb or regular web servers like Apache or LiteSpeed or |
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| 48 | Lighttpd or IIS. The Ruby web servers are run through Rack and the latter can either be setup to use |
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| 49 | FCGI or proxy to a pack of Mongrels/Thin/Ebb servers. |
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| 50 | |
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| 51 | == Apache .htaccess example for FCGI/CGI |
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| 52 | |
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| 53 | # General Apache options |
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| 54 | AddHandler fastcgi-script .fcgi |
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| 55 | AddHandler cgi-script .cgi |
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| 56 | Options +FollowSymLinks +ExecCGI |
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| 57 | |
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| 58 | # If you don't want Rails to look in certain directories, |
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| 59 | # use the following rewrite rules so that Apache won't rewrite certain requests |
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| 60 | # |
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| 61 | # Example: |
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| 62 | # RewriteCond %{REQUEST_URI} ^/notrails.* |
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| 63 | # RewriteRule .* - [L] |
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| 64 | |
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| 65 | # Redirect all requests not available on the filesystem to Rails |
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| 66 | # By default the cgi dispatcher is used which is very slow |
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| 67 | # |
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| 68 | # For better performance replace the dispatcher with the fastcgi one |
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| 69 | # |
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| 70 | # Example: |
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| 71 | # RewriteRule ^(.*)$ dispatch.fcgi [QSA,L] |
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| 72 | RewriteEngine On |
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| 73 | |
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| 74 | # If your Rails application is accessed via an Alias directive, |
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| 75 | # then you MUST also set the RewriteBase in this htaccess file. |
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| 76 | # |
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| 77 | # Example: |
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| 78 | # Alias /myrailsapp /path/to/myrailsapp/public |
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| 79 | # RewriteBase /myrailsapp |
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| 80 | |
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| 81 | RewriteRule ^$ index.html [QSA] |
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| 82 | RewriteRule ^([^.]+)$ $1.html [QSA] |
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| 83 | RewriteCond %{REQUEST_FILENAME} !-f |
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| 84 | RewriteRule ^(.*)$ dispatch.cgi [QSA,L] |
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| 85 | |
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| 86 | # In case Rails experiences terminal errors |
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| 87 | # Instead of displaying this message you can supply a file here which will be rendered instead |
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| 88 | # |
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| 89 | # Example: |
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| 90 | # ErrorDocument 500 /500.html |
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| 91 | |
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| 92 | ErrorDocument 500 "<h2>Application error</h2>Rails application failed to start properly" |
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| 93 | |
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| 94 | |
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| 95 | == Debugging Rails |
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| 96 | |
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| 97 | Sometimes your application goes wrong. Fortunately there are a lot of tools that |
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| 98 | will help you debug it and get it back on the rails. |
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| 99 | |
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| 100 | First area to check is the application log files. Have "tail -f" commands running |
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| 101 | on the server.log and development.log. Rails will automatically display debugging |
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| 102 | and runtime information to these files. Debugging info will also be shown in the |
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| 103 | browser on requests from 127.0.0.1. |
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| 104 | |
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| 105 | You can also log your own messages directly into the log file from your code using |
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| 106 | the Ruby logger class from inside your controllers. Example: |
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| 107 | |
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| 108 | class WeblogController < ActionController::Base |
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| 109 | def destroy |
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| 110 | @weblog = Weblog.find(params[:id]) |
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| 111 | @weblog.destroy |
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| 112 | logger.info("#{Time.now} Destroyed Weblog ID ##{@weblog.id}!") |
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| 113 | end |
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| 114 | end |
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| 115 | |
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| 116 | The result will be a message in your log file along the lines of: |
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| 117 | |
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| 118 | Mon Oct 08 14:22:29 +1000 2007 Destroyed Weblog ID #1 |
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| 119 | |
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| 120 | More information on how to use the logger is at http://www.ruby-doc.org/core/ |
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| 121 | |
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| 122 | Also, Ruby documentation can be found at http://www.ruby-lang.org/ including: |
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| 123 | |
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| 124 | * The Learning Ruby (Pickaxe) Book: http://www.ruby-doc.org/docs/ProgrammingRuby/ |
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| 125 | * Learn to Program: http://pine.fm/LearnToProgram/ (a beginners guide) |
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| 126 | |
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| 127 | These two online (and free) books will bring you up to speed on the Ruby language |
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| 128 | and also on programming in general. |
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| 129 | |
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| 130 | |
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| 131 | == Debugger |
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| 132 | |
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| 133 | Debugger support is available through the debugger command when you start your Mongrel or |
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| 134 | Webrick server with --debugger. This means that you can break out of execution at any point |
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| 135 | in the code, investigate and change the model, AND then resume execution! |
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| 136 | You need to install ruby-debug to run the server in debugging mode. With gems, use 'gem install ruby-debug' |
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| 137 | Example: |
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| 138 | |
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| 139 | class WeblogController < ActionController::Base |
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| 140 | def index |
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| 141 | @posts = Post.find(:all) |
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| 142 | debugger |
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| 143 | end |
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| 144 | end |
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| 145 | |
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| 146 | So the controller will accept the action, run the first line, then present you |
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| 147 | with a IRB prompt in the server window. Here you can do things like: |
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| 148 | |
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| 149 | >> @posts.inspect |
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| 150 | => "[#<Post:0x14a6be8 @attributes={\"title\"=>nil, \"body\"=>nil, \"id\"=>\"1\"}>, |
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| 151 | #<Post:0x14a6620 @attributes={\"title\"=>\"Rails you know!\", \"body\"=>\"Only ten..\", \"id\"=>\"2\"}>]" |
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| 152 | >> @posts.first.title = "hello from a debugger" |
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| 153 | => "hello from a debugger" |
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| 154 | |
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| 155 | ...and even better is that you can examine how your runtime objects actually work: |
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| 156 | |
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| 157 | >> f = @posts.first |
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| 158 | => #<Post:0x13630c4 @attributes={"title"=>nil, "body"=>nil, "id"=>"1"}> |
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| 159 | >> f. |
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| 160 | Display all 152 possibilities? (y or n) |
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| 161 | |
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| 162 | Finally, when you're ready to resume execution, you enter "cont" |
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| 163 | |
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| 164 | |
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| 165 | == Console |
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| 166 | |
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| 167 | You can interact with the domain model by starting the console through <tt>script/console</tt>. |
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| 168 | Here you'll have all parts of the application configured, just like it is when the |
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| 169 | application is running. You can inspect domain models, change values, and save to the |
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| 170 | database. Starting the script without arguments will launch it in the development environment. |
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| 171 | Passing an argument will specify a different environment, like <tt>script/console production</tt>. |
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| 172 | |
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| 173 | To reload your controllers and models after launching the console run <tt>reload!</tt> |
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| 174 | |
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| 175 | == dbconsole |
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| 176 | |
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| 177 | You can go to the command line of your database directly through <tt>script/dbconsole</tt>. |
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| 178 | You would be connected to the database with the credentials defined in database.yml. |
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| 179 | Starting the script without arguments will connect you to the development database. Passing an |
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| 180 | argument will connect you to a different database, like <tt>script/dbconsole production</tt>. |
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| 181 | Currently works for mysql, postgresql and sqlite. |
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| 182 | |
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| 183 | == Description of Contents |
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| 184 | |
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| 185 | app |
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| 186 | Holds all the code that's specific to this particular application. |
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| 187 | |
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| 188 | app/controllers |
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| 189 | Holds controllers that should be named like weblogs_controller.rb for |
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| 190 | automated URL mapping. All controllers should descend from ApplicationController |
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| 191 | which itself descends from ActionController::Base. |
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| 192 | |
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| 193 | app/models |
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| 194 | Holds models that should be named like post.rb. |
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| 195 | Most models will descend from ActiveRecord::Base. |
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| 196 | |
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| 197 | app/views |
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| 198 | Holds the template files for the view that should be named like |
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| 199 | weblogs/index.html.erb for the WeblogsController#index action. All views use eRuby |
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| 200 | syntax. |
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| 201 | |
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| 202 | app/views/layouts |
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| 203 | Holds the template files for layouts to be used with views. This models the common |
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| 204 | header/footer method of wrapping views. In your views, define a layout using the |
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| 205 | <tt>layout :default</tt> and create a file named default.html.erb. Inside default.html.erb, |
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| 206 | call <% yield %> to render the view using this layout. |
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| 207 | |
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| 208 | app/helpers |
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| 209 | Holds view helpers that should be named like weblogs_helper.rb. These are generated |
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| 210 | for you automatically when using script/generate for controllers. Helpers can be used to |
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| 211 | wrap functionality for your views into methods. |
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| 212 | |
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| 213 | config |
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| 214 | Configuration files for the Rails environment, the routing map, the database, and other dependencies. |
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| 215 | |
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| 216 | db |
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| 217 | Contains the database schema in schema.rb. db/migrate contains all |
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| 218 | the sequence of Migrations for your schema. |
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| 219 | |
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| 220 | doc |
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| 221 | This directory is where your application documentation will be stored when generated |
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| 222 | using <tt>rake doc:app</tt> |
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| 223 | |
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| 224 | lib |
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| 225 | Application specific libraries. Basically, any kind of custom code that doesn't |
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| 226 | belong under controllers, models, or helpers. This directory is in the load path. |
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| 227 | |
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| 228 | public |
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| 229 | The directory available for the web server. Contains subdirectories for images, stylesheets, |
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| 230 | and javascripts. Also contains the dispatchers and the default HTML files. This should be |
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| 231 | set as the DOCUMENT_ROOT of your web server. |
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| 232 | |
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| 233 | script |
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| 234 | Helper scripts for automation and generation. |
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| 235 | |
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| 236 | test |
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| 237 | Unit and functional tests along with fixtures. When using the script/generate scripts, template |
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| 238 | test files will be generated for you and placed in this directory. |
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| 239 | |
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| 240 | vendor |
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| 241 | External libraries that the application depends on. Also includes the plugins subdirectory. |
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| 242 | If the app has frozen rails, those gems also go here, under vendor/rails/. |
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| 243 | This directory is in the load path. |
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