CompositeForm::validate

public function validate($fieldsNames = null, $clearErrors = true)
{
	if ($fieldsNames !== null)
	{
		$parentNames = array_filter($fieldsNames, 'is_string');
		$success = $parentNames ? parent::validate($parentNames, $clearErrors) : true;
	}
	else
	{
		$success = parent::validate(null, $clearErrors);
	}
	foreach ($this->nestedForms as $name => $form)
	{
		if ($fieldsNames === null || array_key_exists($name, $fieldsNames) || in_array($name, $fieldsNames, true))
		{
			$innerNames = ArrayHelper::getValue($fieldsNames, $name);
			if (is_array($form))
			{
				$success = parent::validateMultiple($form, $innerNames) && $success;
			}
			else
			{
				$success = $form->validate($innerNames, $clearErrors) && $success;
			}
		}
	}
	return $success;
}