title: how to get the value on form input in cakephp
body: <p>I have:</p>
  
  <pre><code>echo $this-&gt;Form-&gt;input('username', array('label' =&gt; 'Username: '));
  </code></pre>
  
  <p>equivalent to  in traditional php coding..</p>
  
  <p>how can I get the value inputted in that textbox like when you do $val = $_POST['username']; in traditional php coding. </p>
  
  <p>I need this for login validation. thanks</p>