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Jacques Distler 4e14ccc74d Instiki 0.16.3: Rails 2.3.0 
Instiki now runs on the Rails 2.3.0 Candidate Release.
Among other improvements, this means that it now 
automagically selects between WEBrick and Mongrel.

Just run

    ./instiki --daemon
2009-02-04 14:26:08 -06:00

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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
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<title>A Guide to The Rails Command Line</title>
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<a href="index.html" title="Ruby on Rails"><img src="images/rails_logo_remix.gif" alt="Rails" height="140" width="110" /></a>
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<h1 id="site_title"><span>Ruby on Rails</span></h1>
<h2 id="site_title_tagline">Sustainable productivity for web-application development</h2>
<ul id="navMain">
<li class="first-child"><a href="http://www.rubyonrails.org/" title="Ruby on Rails" class="ruby_on_rails">Ruby on Rails</a></li>
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<h2>Chapters</h2>
<ol>
<li>
<a href="#_command_line_basics">Command Line Basics</a>
<ul>
<li><a href="#_rails">rails</a></li>
<li><a href="#_server">server</a></li>
<li><a href="#_generate">generate</a></li>
<li><a href="#_console">console</a></li>
<li><a href="#_dbconsole">dbconsole</a></li>
<li><a href="#_plugin">plugin</a></li>
<li><a href="#_runner">runner</a></li>
<li><a href="#_destroy">destroy</a></li>
<li><a href="#_about">about</a></li>
</ul>
</li>
</ol>
</div>
<div id="content">
<h1>A Guide to The Rails Command Line</h1>
<div id="preamble">
<div class="sectionbody">
<div class="paragraph"><p>Rails comes with every command line tool you&#8217;ll need to</p></div>
<div class="ulist"><ul>
<li>
<p>
Create a Rails application
</p>
</li>
<li>
<p>
Generate models, controllers, database migrations, and unit tests
</p>
</li>
<li>
<p>
Start a development server
</p>
</li>
<li>
<p>
Mess with objects through an interactive shell
</p>
</li>
<li>
<p>
Profile and benchmark your new creation
</p>
</li>
</ul></div>
<div class="paragraph"><p>... and much, much more! (Buy now!)</p></div>
<div class="paragraph"><p>This tutorial assumes you have basic Rails knowledge from reading the Getting Started with Rails Guide.</p></div>
</div>
</div>
<h2 id="_command_line_basics">1. Command Line Basics</h2>
<div class="sectionbody">
<div class="paragraph"><p>There are a few commands that are absolutely critical to your everyday usage of Rails. In the order of how much you&#8217;ll probably use them are:</p></div>
<div class="ulist"><ul>
<li>
<p>
console
</p>
</li>
<li>
<p>
server
</p>
</li>
<li>
<p>
rake
</p>
</li>
<li>
<p>
generate
</p>
</li>
<li>
<p>
rails
</p>
</li>
</ul></div>
<div class="paragraph"><p>Let&#8217;s create a simple Rails application to step through each of these commands in context.</p></div>
<h3 id="_rails">1.1. rails</h3>
<div class="paragraph"><p>The first thing we&#8217;ll want to do is create a new Rails application by running the <tt>rails</tt> command after installing Rails.</p></div>
<div class="admonitionblock">
<table><tr>
<td class="icon">
<img src="./images/icons/note.png" alt="Note" />
</td>
<td class="content">You know you need the rails gem installed by typing <tt>gem install rails</tt> first, right? Okay, okay, just making sure.</td>
</tr></table>
</div>
<div class="listingblock">
<div class="content"><!-- Generator: GNU source-highlight 2.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><tt>$ rails commandsapp
create
create app/controllers
create app/helpers
create app/models
<span style="color: #990000">...</span>
<span style="color: #990000">...</span>
create log/production<span style="color: #990000">.</span>log
create log/development<span style="color: #990000">.</span>log
create log/test<span style="color: #990000">.</span>log</tt></pre></div></div>
<div class="paragraph"><p>Rails will set you up with what seems like a huge amount of stuff for such a tiny command! You&#8217;ve got the entire Rails directory structure now with all the code you need to run our simple application right out of the box.</p></div>
<div class="admonitionblock">
<table><tr>
<td class="icon">
<img src="./images/icons/note.png" alt="Note" />
</td>
<td class="content">This output will seem very familiar when we get to the <tt>generate</tt> command. Creepy foreshadowing!</td>
</tr></table>
</div>
<h3 id="_server">1.2. server</h3>
<div class="paragraph"><p>Let&#8217;s try it! The <tt>server</tt> command launches a small web server named WEBrick which comes bundled with Ruby. You&#8217;ll use this any time you want to view your work through a web browser.</p></div>
<div class="admonitionblock">
<table><tr>
<td class="icon">
<img src="./images/icons/note.png" alt="Note" />
</td>
<td class="content">WEBrick isn&#8217;t your only option for serving Rails. We&#8217;ll get to that in a later section. [XXX: which section]</td>
</tr></table>
</div>
<div class="paragraph"><p>Here we&#8217;ll flex our <tt>server</tt> command, which without any prodding of any kind will run our new shiny Rails app:</p></div>
<div class="listingblock">
<div class="content"><!-- Generator: GNU source-highlight 2.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><tt>$ cd commandsapp
$ <span style="color: #990000">.</span>/script/server
<span style="color: #990000">=&gt;</span> Booting WEBrick<span style="color: #990000">...</span>
<span style="color: #990000">=&gt;</span> Rails <span style="color: #993399">2.2</span><span style="color: #990000">.</span><span style="color: #993399">0</span> application started on http<span style="color: #990000">://</span><span style="color: #993399">0.0</span><span style="color: #990000">.</span><span style="color: #993399">0.0</span><span style="color: #990000">:</span><span style="color: #993399">3000</span>
<span style="color: #990000">=&gt;</span> Ctrl-C to shutdown server<span style="color: #990000">;</span> call with --help <span style="font-weight: bold"><span style="color: #0000FF">for</span></span> options
<span style="color: #990000">[</span><span style="color: #993399">2008</span>-<span style="color: #993399">11</span>-<span style="color: #993399">04</span> <span style="color: #993399">10</span><span style="color: #990000">:</span><span style="color: #993399">11</span><span style="color: #990000">:</span><span style="color: #993399">38</span><span style="color: #990000">]</span> INFO WEBrick <span style="color: #993399">1.3</span><span style="color: #990000">.</span><span style="color: #993399">1</span>
<span style="color: #990000">[</span><span style="color: #993399">2008</span>-<span style="color: #993399">11</span>-<span style="color: #993399">04</span> <span style="color: #993399">10</span><span style="color: #990000">:</span><span style="color: #993399">11</span><span style="color: #990000">:</span><span style="color: #993399">38</span><span style="color: #990000">]</span> INFO ruby <span style="color: #993399">1.8</span><span style="color: #990000">.</span><span style="color: #993399">5</span> <span style="color: #990000">(</span><span style="color: #993399">2006</span>-<span style="color: #993399">12</span>-<span style="color: #993399">04</span><span style="color: #990000">)</span> <span style="color: #990000">[</span>i486-linux<span style="color: #990000">]</span>
<span style="color: #990000">[</span><span style="color: #993399">2008</span>-<span style="color: #993399">11</span>-<span style="color: #993399">04</span> <span style="color: #993399">10</span><span style="color: #990000">:</span><span style="color: #993399">11</span><span style="color: #990000">:</span><span style="color: #993399">38</span><span style="color: #990000">]</span> INFO WEBrick<span style="color: #990000">::</span>HTTPServer<span style="font-style: italic"><span style="color: #9A1900">#start: pid=18994 port=3000</span></span></tt></pre></div></div>
<div class="paragraph"><p>WHOA. With just three commands we whipped up a Rails server listening on port 3000. Go! Go right now to your browser and go to <a href="http://localhost:3000">http://localhost:3000</a>. I&#8217;ll wait.</p></div>
<div class="paragraph"><p>See? Cool! It doesn&#8217;t do much yet, but we&#8217;ll change that.</p></div>
<h3 id="_generate">1.3. generate</h3>
<div class="paragraph"><p>The <tt>generate</tt> command uses templates to create a whole lot of things. You can always find out what&#8217;s available by running <tt>generate</tt> by itself. Let&#8217;s do that:</p></div>
<div class="listingblock">
<div class="content"><!-- Generator: GNU source-highlight 2.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><tt>$ <span style="color: #990000">.</span>/script/generate
Usage<span style="color: #990000">:</span> <span style="color: #990000">.</span>/script/generate generator <span style="color: #990000">[</span>options<span style="color: #990000">]</span> <span style="color: #990000">[</span>args<span style="color: #990000">]</span>
<span style="color: #990000">...</span>
<span style="color: #990000">...</span>
Installed Generators
Builtin<span style="color: #990000">:</span> controller<span style="color: #990000">,</span> integration_test<span style="color: #990000">,</span> mailer<span style="color: #990000">,</span> migration<span style="color: #990000">,</span> model<span style="color: #990000">,</span> observer<span style="color: #990000">,</span> performance_test<span style="color: #990000">,</span> plugin<span style="color: #990000">,</span> resource<span style="color: #990000">,</span> scaffold<span style="color: #990000">,</span> session_migration
<span style="color: #990000">...</span>
<span style="color: #990000">...</span></tt></pre></div></div>
<div class="admonitionblock">
<table><tr>
<td class="icon">
<img src="./images/icons/note.png" alt="Note" />
</td>
<td class="content">You can install more generators through generator gems, portions of plugins you&#8217;ll undoubtedly install, and you can even create your own!</td>
</tr></table>
</div>
<div class="paragraph"><p>Using generators will save you a large amount of time by writing <strong>boilerplate code</strong> for you&#8201;&#8212;&#8201;necessary for the darn thing to work, but not necessary for you to spend time writing. That&#8217;s what we have computers for, right?</p></div>
<div class="paragraph"><p>Let&#8217;s make our own controller with the controller generator. But what command should we use? Let&#8217;s ask the generator:</p></div>
<div class="admonitionblock">
<table><tr>
<td class="icon">
<img src="./images/icons/note.png" alt="Note" />
</td>
<td class="content">All Rails console utilities have help text. As with most *NIX utilities, you can try adding <tt>--help</tt> or <tt>-h</tt> to the end, for example <tt>./script/server --help</tt>.</td>
</tr></table>
</div>
<div class="listingblock">
<div class="content"><!-- Generator: GNU source-highlight 2.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><tt>$ <span style="color: #990000">.</span>/script/generate controller
Usage<span style="color: #990000">:</span> <span style="color: #990000">.</span>/script/generate controller ControllerName <span style="color: #990000">[</span>options<span style="color: #990000">]</span>
<span style="color: #990000">...</span>
<span style="color: #990000">...</span>
Example<span style="color: #990000">:</span>
`<span style="color: #990000">.</span>/script/generate controller CreditCard open debit credit close`
Credit card controller with URLs like /credit_card/debit<span style="color: #990000">.</span>
Controller<span style="color: #990000">:</span> app/controllers/credit_card_controller<span style="color: #990000">.</span>rb
Views<span style="color: #990000">:</span> app/views/credit_card/debit<span style="color: #990000">.</span>html<span style="color: #990000">.</span>erb <span style="color: #990000">[...]</span>
Helper<span style="color: #990000">:</span> app/helpers/credit_card_helper<span style="color: #990000">.</span>rb
Test<span style="color: #990000">:</span> test/functional/credit_card_controller_test<span style="color: #990000">.</span>rb
Modules Example<span style="color: #990000">:</span>
`<span style="color: #990000">.</span>/script/generate controller <span style="color: #FF0000">'admin/credit_card'</span> <span style="font-weight: bold"><span style="color: #0000FF">suspend</span></span> late_fee`
Credit card admin controller with URLs /admin/credit_card/suspend<span style="color: #990000">.</span>
Controller<span style="color: #990000">:</span> app/controllers/admin/credit_card_controller<span style="color: #990000">.</span>rb
Views<span style="color: #990000">:</span> app/views/admin/credit_card/debit<span style="color: #990000">.</span>html<span style="color: #990000">.</span>erb <span style="color: #990000">[...]</span>
Helper<span style="color: #990000">:</span> app/helpers/admin/credit_card_helper<span style="color: #990000">.</span>rb
Test<span style="color: #990000">:</span> test/functional/admin/credit_card_controller_test<span style="color: #990000">.</span>rb</tt></pre></div></div>
<div class="paragraph"><p>Ah, the controller generator is expecting parameters in the form of <tt>generate controller ControllerName action1 action2</tt>. Let&#8217;s make a <tt>Greetings</tt> controller with an action of <strong>hello</strong>, which will say something nice to us.</p></div>
<div class="listingblock">
<div class="content"><!-- Generator: GNU source-highlight 2.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><tt>$ <span style="color: #990000">.</span>/script/generate controller Greeting hello
exists app/controllers<span style="color: #990000">/</span>
exists app/helpers<span style="color: #990000">/</span>
create app/views/greeting
exists test/functional<span style="color: #990000">/</span>
create app/controllers/greetings_controller<span style="color: #990000">.</span>rb
create test/functional/greetings_controller_test<span style="color: #990000">.</span>rb
create app/helpers/greetings_helper<span style="color: #990000">.</span>rb
create app/views/greetings/hello<span style="color: #990000">.</span>html<span style="color: #990000">.</span>erb</tt></pre></div></div>
<div class="paragraph"><p>Look there! Now what all did this generate? It looks like it made sure a bunch of directories were in our application, and created a controller file, a functional test file, a helper for the view, and a view file.</p></div>
<div class="paragraph"><p>Let&#8217;s check out the controller and modify it a little (in <tt>app/controllers/greeting_controller.rb</tt>):</p></div>
<div class="listingblock">
<div class="content"><!-- Generator: GNU source-highlight 2.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><tt><span style="font-weight: bold"><span style="color: #0000FF">class</span></span> GreetingController <span style="color: #990000">&lt;</span> ApplicationController
<span style="font-weight: bold"><span style="color: #0000FF">def</span></span> hello
<span style="color: #009900">@message</span> <span style="color: #990000">=</span> <span style="color: #FF0000">"Hello, how are you today? I am exuberant!"</span>
<span style="font-weight: bold"><span style="color: #0000FF">end</span></span>
<span style="font-weight: bold"><span style="color: #0000FF">end</span></span></tt></pre></div></div>
<div class="paragraph"><p>Then the view, to display our nice message (in <tt>app/views/greeting/hello.html.erb</tt>):</p></div>
<div class="listingblock">
<div class="content"><!-- Generator: GNU source-highlight 2.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><tt><span style="font-weight: bold"><span style="color: #0000FF">&lt;h1&gt;</span></span>A Greeting for You!<span style="font-weight: bold"><span style="color: #0000FF">&lt;/h1&gt;</span></span>
<span style="font-weight: bold"><span style="color: #0000FF">&lt;p&gt;</span></span>&lt;%= @message %&gt;<span style="font-weight: bold"><span style="color: #0000FF">&lt;/p&gt;</span></span></tt></pre></div></div>
<div class="paragraph"><p>Deal. Go check it out in your browser. Fire up your server. Remember? <tt>./script/server</tt> at the root of your Rails application should do it.</p></div>
<div class="listingblock">
<div class="content"><!-- Generator: GNU source-highlight 2.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><tt>$ <span style="color: #990000">.</span>/script/server
<span style="color: #990000">=&gt;</span> Booting WEBrick<span style="color: #990000">...</span></tt></pre></div></div>
<div class="paragraph"><p>The URL will be <tt>http://localhost:3000/greetings/hello</tt>. I&#8217;ll wait for you to be suitably impressed.</p></div>
<div class="admonitionblock">
<table><tr>
<td class="icon">
<img src="./images/icons/note.png" alt="Note" />
</td>
<td class="content">With a normal, plain-old Rails application, your URLs will generally follow the pattern of <a href="http://(host)/(controller)/(action">http://(host)/(controller)/(action</a>), and a URL like <a href="http://(host)/(controller">http://(host)/(controller</a>) will hit the <strong>index</strong> action of that controller.</td>
</tr></table>
</div>
<div class="paragraph"><p>"What about data, though?", you ask over a cup of coffee. Rails comes with a generator for data models too. Can you guess its generator name?</p></div>
<div class="listingblock">
<div class="content"><!-- Generator: GNU source-highlight 2.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><tt>$ <span style="color: #990000">.</span>/script/generate model
Usage<span style="color: #990000">:</span> <span style="color: #990000">.</span>/script/generate model ModelName <span style="color: #990000">[</span>field<span style="color: #990000">:</span><span style="font-weight: bold"><span style="color: #0000FF">type</span></span><span style="color: #990000">,</span> field<span style="color: #990000">:</span><span style="font-weight: bold"><span style="color: #0000FF">type</span></span><span style="color: #990000">]</span>
<span style="color: #990000">...</span>
Examples<span style="color: #990000">:</span>
`<span style="color: #990000">.</span>/script/generate model account`
creates an Account model<span style="color: #990000">,</span> <span style="font-weight: bold"><span style="color: #0000FF">test</span></span><span style="color: #990000">,</span> fixture<span style="color: #990000">,</span> and migration<span style="color: #990000">:</span>
Model<span style="color: #990000">:</span> app/models/account<span style="color: #990000">.</span>rb
Test<span style="color: #990000">:</span> test/unit/account_test<span style="color: #990000">.</span>rb
Fixtures<span style="color: #990000">:</span> test/fixtures/accounts<span style="color: #990000">.</span>yml
Migration<span style="color: #990000">:</span> db/migrate/XXX_add_accounts<span style="color: #990000">.</span>rb
`<span style="color: #990000">.</span>/script/generate model post title<span style="color: #990000">:</span>string body<span style="color: #990000">:</span>text published<span style="color: #990000">:</span>boolean`
creates a Post model with a string title<span style="color: #990000">,</span> text body<span style="color: #990000">,</span> and published flag<span style="color: #990000">.</span></tt></pre></div></div>
<div class="paragraph"><p>But instead of generating a model directly (which we&#8217;ll be doing later), let&#8217;s set up a scaffold. A <strong>scaffold</strong> in Rails is a full set of model, database migration for that model, controller to manipulate it, views to view and manipulate the data, and a test suite for each of the above.</p></div>
<div class="paragraph"><p>Let&#8217;s set up a simple resource called "HighScore" that will keep track of our highest score on video games we play.</p></div>
<div class="listingblock">
<div class="content"><!-- Generator: GNU source-highlight 2.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><tt>$ <span style="color: #990000">.</span>/script/generate scaffold HighScore game<span style="color: #990000">:</span>string score<span style="color: #990000">:</span>integer
exists app/models<span style="color: #990000">/</span>
exists app/controllers<span style="color: #990000">/</span>
exists app/helpers<span style="color: #990000">/</span>
create app/views/high_scores
create app/views/layouts<span style="color: #990000">/</span>
exists test/functional<span style="color: #990000">/</span>
create test/unit<span style="color: #990000">/</span>
create public/stylesheets<span style="color: #990000">/</span>
create app/views/high_scores/index<span style="color: #990000">.</span>html<span style="color: #990000">.</span>erb
create app/views/high_scores/show<span style="color: #990000">.</span>html<span style="color: #990000">.</span>erb
create app/views/high_scores/new<span style="color: #990000">.</span>html<span style="color: #990000">.</span>erb
create app/views/high_scores/edit<span style="color: #990000">.</span>html<span style="color: #990000">.</span>erb
create app/views/layouts/high_scores<span style="color: #990000">.</span>html<span style="color: #990000">.</span>erb
create public/stylesheets/scaffold<span style="color: #990000">.</span>css
create app/controllers/high_scores_controller<span style="color: #990000">.</span>rb
create test/functional/high_scores_controller_test<span style="color: #990000">.</span>rb
create app/helpers/high_scores_helper<span style="color: #990000">.</span>rb
route map<span style="color: #990000">.</span>resources <span style="color: #990000">:</span>high_scores
dependency model
exists app/models<span style="color: #990000">/</span>
exists test/unit<span style="color: #990000">/</span>
create test/fixtures<span style="color: #990000">/</span>
create app/models/high_score<span style="color: #990000">.</span>rb
create test/unit/high_score_test<span style="color: #990000">.</span>rb
create test/fixtures/high_scores<span style="color: #990000">.</span>yml
exists db/migrate
create db/migrate<span style="color: #990000">/</span>20081217071914_create_high_scores<span style="color: #990000">.</span>rb</tt></pre></div></div>
<div class="paragraph"><p>Taking it from the top - the generator checks that there exist the directories for models, controllers, helpers, layouts, functional and unit tests, stylesheets, creates the views, controller, model and database migration for HighScore (creating the <tt>high_scores</tt> table and fields), takes care of the route for the <strong>resource</strong>, and new tests for everything.</p></div>
<div class="paragraph"><p>The migration requires that we <strong>migrate</strong>, that is, run some Ruby code (living in that <tt>20081217071914_create_high_scores.rb</tt>) to modify the schema of our database. Which database? The sqlite3 database that Rails will create for you when we run the <tt>rake db:migrate</tt> command. We&#8217;ll talk more about Rake in-depth in a little while.</p></div>
<div class="admonitionblock">
<table><tr>
<td class="icon">
<img src="./images/icons/note.png" alt="Note" />
</td>
<td class="content">Hey. Install the sqlite3-ruby gem while you&#8217;re at it. <tt>gem install sqlite3-ruby</tt></td>
</tr></table>
</div>
<div class="listingblock">
<div class="content"><!-- Generator: GNU source-highlight 2.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><tt>$ rake db<span style="color: #990000">:</span>migrate
<span style="color: #990000">(</span><span style="font-weight: bold"><span style="color: #0000FF">in</span></span> /home/commandsapp<span style="color: #990000">)</span>
<span style="color: #990000">==</span> CreateHighScores<span style="color: #990000">:</span> migrating <span style="color: #990000">===============================================</span>
-- create_table<span style="color: #990000">(:</span>high_scores<span style="color: #990000">)</span>
-<span style="color: #990000">&gt;</span> <span style="color: #993399">0</span><span style="color: #990000">.</span>0070s
<span style="color: #990000">==</span> CreateHighScores<span style="color: #990000">:</span> migrated <span style="color: #990000">(</span><span style="color: #993399">0</span><span style="color: #990000">.</span>0077s<span style="color: #990000">)</span> <span style="color: #990000">======================================</span></tt></pre></div></div>
<div class="admonitionblock">
<table><tr>
<td class="icon">
<img src="./images/icons/note.png" alt="Note" />
</td>
<td class="content">Let&#8217;s talk about unit tests. Unit tests are code that tests and makes assertions about code. In unit testing, we take a little part of code, say a method of a model, and test its inputs and outputs. Unit tests are your friend. The sooner you make peace with the fact that your quality of life will drastically increase when you unit test your code, the better. Seriously. We&#8217;ll make one in a moment.</td>
</tr></table>
</div>
<div class="paragraph"><p>Let&#8217;s see the interface Rails created for us. ./script/server; <a href="http://localhost:3000/high_scores">http://localhost:3000/high_scores</a></p></div>
<div class="paragraph"><p>We can create new high scores (55,160 on Space Invaders!)</p></div>
<h3 id="_console">1.4. console</h3>
<div class="paragraph"><p>The <tt>console</tt> command lets you interact with your Rails application from the command line. On the underside, <tt>script/console</tt> uses IRB, so if you&#8217;ve ever used it, you&#8217;ll be right at home. This is useful for testing out quick ideas with code and changing data server-side without touching the website.</p></div>
<h3 id="_dbconsole">1.5. dbconsole</h3>
<div class="paragraph"><p><tt>dbconsole</tt> figures out which database you&#8217;re using and drops you into whichever command line interface you would use with it (and figures out the command line parameters to give to it, too!). It supports MySQL, PostgreSQL, SQLite and SQLite3.</p></div>
<h3 id="_plugin">1.6. plugin</h3>
<div class="paragraph"><p>The <tt>plugin</tt> command simplifies plugin management; think a miniature version of the Gem utility. Let&#8217;s walk through installing a plugin. You can call the sub-command <strong>discover</strong>, which sifts through repositories looking for plugins, or call <strong>source</strong> to add a specific repository of plugins, or you can specify the plugin location directly.</p></div>
<div class="paragraph"><p>Let&#8217;s say you&#8217;re creating a website for a client who wants a small accounting system. Every event having to do with money must be logged, and must never be deleted. Wouldn&#8217;t it be great if we could override the behavior of a model to never actually take its record out of the database, but <strong>instead</strong>, just set a field?</p></div>
<div class="paragraph"><p>There is such a thing! The plugin we&#8217;re installing is called "acts_as_paranoid", and it lets models implement a "deleted_at" column that gets set when you call destroy. Later, when calling find, the plugin will tack on a database check to filter out "deleted" things.</p></div>
<div class="listingblock">
<div class="content"><!-- Generator: GNU source-highlight 2.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><tt>$ <span style="color: #990000">.</span>/script/plugin install http<span style="color: #990000">:</span>//svn<span style="color: #990000">.</span>techno-weenie<span style="color: #990000">.</span>net/projects/plugins/acts_as_paranoid
<span style="color: #990000">+</span> <span style="color: #990000">.</span>/CHANGELOG
<span style="color: #990000">+</span> <span style="color: #990000">.</span>/MIT-LICENSE
<span style="color: #990000">...</span>
<span style="color: #990000">...</span></tt></pre></div></div>
<h3 id="_runner">1.7. runner</h3>
<div class="paragraph"><p><tt>runner</tt> runs Ruby code in the context of Rails non-interactively. For instance:</p></div>
<div class="listingblock">
<div class="content"><!-- Generator: GNU source-highlight 2.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><tt>$ <span style="color: #990000">.</span>/script/runner <span style="color: #FF0000">"Model.long_running_method"</span></tt></pre></div></div>
<h3 id="_destroy">1.8. destroy</h3>
<div class="paragraph"><p>Think of <tt>destroy</tt> as the opposite of <tt>generate</tt>. It&#8217;ll figure out what generate did, and undo it. Believe you-me, the creation of this tutorial used this command many times!</p></div>
<div class="listingblock">
<div class="content"><!-- Generator: GNU source-highlight 2.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><tt>$ <span style="color: #990000">.</span>/script/generate model Oops
exists app/models<span style="color: #990000">/</span>
exists test/unit<span style="color: #990000">/</span>
exists test/fixtures<span style="color: #990000">/</span>
create app/models/oops<span style="color: #990000">.</span>rb
create test/unit/oops_test<span style="color: #990000">.</span>rb
create test/fixtures/oops<span style="color: #990000">.</span>yml
exists db/migrate
create db/migrate<span style="color: #990000">/</span>20081221040817_create_oops<span style="color: #990000">.</span>rb
$ <span style="color: #990000">.</span>/script/destroy model Oops
notempty db/migrate
notempty db
rm db/migrate<span style="color: #990000">/</span>20081221040817_create_oops<span style="color: #990000">.</span>rb
rm test/fixtures/oops<span style="color: #990000">.</span>yml
rm test/unit/oops_test<span style="color: #990000">.</span>rb
rm app/models/oops<span style="color: #990000">.</span>rb
notempty test/fixtures
notempty <span style="font-weight: bold"><span style="color: #0000FF">test</span></span>
notempty test/unit
notempty <span style="font-weight: bold"><span style="color: #0000FF">test</span></span>
notempty app/models
notempty app</tt></pre></div></div>
<h3 id="_about">1.9. about</h3>
<div class="paragraph"><p>Check it: Version numbers for Ruby, RubyGems, Rails, the Rails subcomponents, your application&#8217;s folder, the current Rails environment name, your app&#8217;s database adapter, and schema version! <tt>about</tt> is useful when you need to ask help, check if a security patch might affect you, or when you need some stats for an existing Rails installation.</p></div>
<div class="listingblock">
<div class="content"><!-- Generator: GNU source-highlight 2.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><tt>$ <span style="color: #990000">.</span>/script/about
About your application<span style="color: #FF0000">'s environment</span>
<span style="color: #FF0000">Ruby version 1.8.6 (i486-linux)</span>
<span style="color: #FF0000">RubyGems version 1.3.1</span>
<span style="color: #FF0000">Rails version 2.2.0</span>
<span style="color: #FF0000">Active Record version 2.2.0</span>
<span style="color: #FF0000">Action Pack version 2.2.0</span>
<span style="color: #FF0000">Active Resource version 2.2.0</span>
<span style="color: #FF0000">Action Mailer version 2.2.0</span>
<span style="color: #FF0000">Active Support version 2.2.0</span>
<span style="color: #FF0000">Edge Rails revision unknown</span>
<span style="color: #FF0000">Application root /home/commandsapp</span>
<span style="color: #FF0000">Environment development</span>
<span style="color: #FF0000">Database adapter sqlite3</span>
<span style="color: #FF0000">Database schema version 20081217073400</span></tt></pre></div></div>
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