yii-bootstrap 3 BsHtml :: buttonToolbar在表单中的用法

I know that simple textfield element in yii is formed like this

<div class="row">
    <?php echo $form->labelEx($model,'username'); ?>
    <?php echo $form->textField($model,'username',array('size'=>30,'maxlength'=>30)); ?>
    <?php echo $form->error($model,'username'); ?>
</div>

now I need to make some radio button type thing in my form to choose between 2 options and send choice later via form.

I've found cool looking Button toolbar

http://bootstrap3.pascal-brewing.de/site/components#btn-groups-toolbar

echo BsHtml::buttonToolbar(array(
    array(
        'items' => array(
            array(
                'label' => 'first button'
            ),
        )
    ),
    array(
        'items' => array(
            array(
                'label' => 'second button'
            ),
         )
    )
));

which works great in html, but how can I tell these buttons about my $model and my attributes ? Cannot find any explanations about where to put model and other attributes in that code :(

I don't think it allows for that if you want to use them as form elements you would probably have to have a hidden input for the attribute and then do some javascript/jquery to update the value of that hidden input based off of the selected button from the button bar.