Antispam for Yii form

_antispam.php

<div class="antispam">
    <?= $form->textField($model, '_yii_antispam'); ?>
    <?= $model->_yii_antispam_message ?>
    <script type="text/javascript">
        $('.antispam').hide();
        $(".antispam input[name='<?= get_class($model) ?>[_yii_antispam]']").val('human');
    </script>
</div>

MyFormModel.php

<?php

/*
 * Prevent automated POST (actually non-GET) requests by checking a form
 * attribute set by JavaScript, in the hope that spammers will not execute
 * JavaScript.
 *
 * Usage:
 *  1. Extend MyFormModel instead of CFormModel
 *         class ContactForm extends MyFormModel {}
 *  2. If necessary, use `array_merge(parent::rules(), array(...))` when
 *     defining validation rules
 *         public function rules() {
 *             return array_merge(parent::rules(), array(
 *                 // rules
 *             ));
 *         }
 *  3. When rendering, include `_antispam` inside the form widget
 *         <?= $this->renderPartial('//shared/_antispam', array(
 *             'form' => $form,
 *             'model' => $model)) ?>
 */

class MyFormModel extends CFormModel {

    public $_yii_antispam;
    public $_yii_antispam_message = 'Type "human" if you are not a robot.';

    public function rules() {
        return array(
            array(
                '_yii_antispam', 'compare',
                'compareValue' => 'human',
                'message' => $this->_yii_antispam_message,
            ),
        );
    }
}