title: cakePHP: $this->Form->input() - How to set a select default option
body: <p>In my view I have:</p>
  
  <pre><code>echo $this-&gt;Form-&gt;input('category_parent_id');
  </code></pre>
  
  <p>and it outputs:</p>
  
  <pre><code>&lt;option value="1"&gt;category name 1&lt;/option&gt;
  &lt;option value="2"&gt;category name 2&lt;/option&gt;
  ...
  </code></pre>
  
  <p>but how do I tell it input() that I want a default option like so?:</p>
  
  <pre><code>&lt;option value=""&gt;select a category&lt;/option&gt;
  &lt;option value="1"&gt;category name 1&lt;/option&gt;
  &lt;option value="2"&gt;category name 2&lt;/option&gt;
  ...
  </code></pre>
  
  <p>nvm, found it:</p>
  
  <pre><code>echo $this-&gt;Form-&gt;input('category_parent_id', array('empty' =&gt; 'Select a parent category'));
  </code></pre>