title: How to validate at least one checkbox in Magento?
body: <p>I have a dynamic form with minimum one checkbox as an array.</p>
  
  <pre><code>&lt;form action="url" method="post" id="whatever"&gt;
    &lt;input class="checkbox" type="checkbox" name="item_ids[]" value="101" /&gt;
    &lt;input class="checkbox" type="checkbox" name="item_ids[]" value="102" /&gt;
    &lt;input class="checkbox validate-one-required" type="checkbox" name="item_ids[]" value="103" /&gt;
    &lt;button type="submit"&gt;
  &lt;/form&gt;
  
  &lt;script type="text/javascript"&gt;
      //&lt; ![CDATA[
      var customForm = new VarienForm('whatever');
      //]]&gt;
  &lt;/script&gt;
  </code></pre>
  
  <p>I tried to use the hint from several forums to add the "validate-one-required" to the last checkbox in the group. But when I try to submit my form and I checked the first checkbox Magento told me that I have to select at least one option. Funny! I guess I did it.</p>
  
  <p>Is there something else especially in the javascript area I had to add?</p>