title: How to validate an array with WTForms and flask?
body: <p>I have a custom form which submits an array:</p>
  
  <pre><code>&lt;form method="post" action="/doit"&gt;
      &lt;input type="text" name="mylist" value="one"&gt;
      &lt;input type="text" name="mylist" value="two"&gt;
      &lt;input type="text" name="mylist" value="three"&gt;
      &lt;input type="text" name="mylist" value="four"&gt;
  &lt;/form&gt;
  </code></pre>
  
  <p>How do I build a WTForm so that <code>mylist</code> requires at least one item when validating the form?</p>