How to add class to form input field?

I am trying to add jscolor to an input field but it is not working with me!

In configure function:

public function configure() {
        unset($this['created_at'],$this['clicks']);
        $this->widgetSchema['background_color']->sfWidgetFormInput('class'=> 'jscolor');
} 

I also tried adding the below in BaseForm:

$this->setWidgets(array(
            'id'            => new sfWidgetFormInputHidden(),
            'background_color'  => new sfWidgetFormInput(array('class'=> 'jscolor')),
            'url_link'      => new sfWidgetFormInput(),
            'status'        => new sfWidgetFormInput(),
        ));

Error: Class is not allowed in the sfWidgetFormInput function !

I want to add a class jscolor! How can i add it via JavaScript or using this configuration?

You need to add your class to your input during rendering the form element in your template as :

<?php echo $form['background_color']->render(array('class' => 'jscolor')); ?>