add_topics-notes.html

<h1>let's add topics</h1>

<ul>
<li>what exactly do we mean by "add topics?" </li>
<li>rails "scaffolding" to generate some pages (and code)</li>
<li>set up database with a new table (migration)</li>
<li>review what we did</li>
</ul>

<h1>adding topics</h1>

<ul>
<li>topic will have a title and a description</li>
<li>we will enable basic "CRUD" actions
<ul>
<li>Create - enter a new topic</li>
<li>Read - see everyone's topics</li>
<li>Update - change the topics you entered</li>
<li>Delete - remove your topics from the system </li>
</ul></li>
</ul>

<p>.</p>

<pre><code>ruby script/generate scaffold topic title:string description:text
rake db:migrate
</code></pre>

<p>.</p>

<pre><code>http://localhost:3000/topics
</code></pre>

<h1>What did we just do?</h1>

<ul>
<li>a model
<ul>
<li>create    app/models/topic.rb</li>
<li>create    db/migrate/20090611073227<em>create</em>topics.rb</li>
</ul></li>
<li>4 views
<ul>
<li>create  app/views/topics/index.html.erb</li>
<li>create  app/views/topics/show.html.erb</li>
<li>create  app/views/topics/new.html.erb</li>
<li>create  app/views/topics/edit.html.erb</li>
</ul></li>
<li>a controller
<ul>
<li>create  app/controllers/topics_controller.rb</li>
<li>route  map.resources :topics</li>
</ul></li>
</ul>

<p><img src="http://www.gliffy.com/pubdoc/1734447/L.jpg" alt="Architecture" title="" /></p>

<h1>Model-View-Controller</h1>

<ul>
<li><strong>Model</strong>
<ul>
<li>represents what is in the database </li>
<li>ActiveRecord</li>
</ul></li>
<li><strong>View</strong>
<ul>
<li>the model rendered as HTML </li>
<li>ActionView, erb</li>
</ul></li>
<li><strong>Controller</strong>
<ul>
<li>receives HTTP actions (GET, POST, PUT, DELETE)</li>
<li>decides what to do, typically rendering a view </li>
<li>ActionController</li>
</ul></li>
</ul>

<p>.</p>

<pre><code>git add -A
git commit -m 'topic crud'
git push heroku master
heroku rake db:migrate
git push
</code></pre>