title: Don't show other validation messages without presence
body: <p>Right now, I have a <code>User</code> model with a <code>username</code> field that's being validated by:</p>
  
  <pre><code>validates :username, 
      :presence =&gt; true,
      :length =&gt; { :in =&gt; 3..60 }, 
      :format =&gt; { :with =&gt; /^[a-zA-Z0-9\-_ ]+$/ }
  </code></pre>
  
  <p>How can I hide the <code>:length</code> and <code>:format</code> validation errors if <code>:presence</code> is not met?</p>