Shopware 4 - Add 2 new colums to Order-Model & fill them through order process

Bootstrap.php

<?php
/**
 * Shopware 4.0
 * Copyright © 2012 shopware AG
 *
 * According to our dual licensing model, this program can be used either
 * under the terms of the GNU Affero General Public License, version 3,
 * or under a proprietary license.
 *
 * The texts of the GNU Affero General Public License with an additional
 * permission and of our proprietary license can be found at and
 * in the LICENSE file you have received along with this program.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Affero General Public License for more details.
 *
 * "Shopware" is a registered trademark of shopware AG.
 * The licensing of the program under the AGPLv3 does not imply a
 * trademark license. Therefore any rights, title and interest in
 * our trademarks remain entirely with us.
 *
 * @category   Shopware
 * @package    Shopware_Plugins
 * @subpackage AdvancedMenu
 * @copyright  Copyright (c) 2012, shopware AG (http://www.shopware.de)
 * @version    $Id$
 * @author     Heiner Lohaus
 * @author     $Author$
 */
/**
 * Shopware AdvancedMenu Plugin
 *
 * todo@all: Documentation
 */
class Shopware_Plugins_Frontend_SwagTestCases_Bootstrap extends Shopware_Components_Plugin_Bootstrap
{
    /**
     * Install plugin method
     *
     * @return bool
     */
    public function install()
    {

      // Add 2 new columns to s_order_attributes
	    Shopware()->Models()->addAttribute('s_order_attributes','myPrx','Test1','varchar(255)', false, 0);
	    Shopware()->Models()->addAttribute('s_order_attributes','myPrx','Test2','varchar(255)', false, 0);

		$metaDataCache  = Shopware()->Models()->getConfiguration()->getMetadataCacheImpl();
		$metaDataCache->deleteAll();

	    Shopware()->Models()->generateAttributeModels(
	             array('s_order_attributes')
	    );
	    
	    $this->subscribeEvent('Shopware_Modules_Order_SendMail_FilterVariables','OnBeforeSendOrderConfirmation');

	    return array('success' => true, 'invalidateCache' => array('backend', 'proxy'));
    }

	public function OnBeforeSendOrderConfirmation (Enlight_Event_EventArgs $args){


		$orderVariables = $args->getReturn();
		$ordernumber = $orderVariables["ordernumber"];

		// Find order id by order number
		$order = Shopware()->Models()->getRepository('Shopware\Models\Order\Order')->findOneBy(array('number'=>$ordernumber));

		$orderAttributeModel = Shopware()->Models()->getRepository('Shopware\Models\Attribute\Order')->findOneBy(
			array("orderId"=>$order->getId()));


		if ($orderAttributeModel instanceof \Shopware\Models\Attribute\Order){
			$orderAttributeModel->setMyPrxTest1("Test");
			$orderAttributeModel->setMyPrxTest2("Test2");
			Shopware()->Models()->persist($orderAttributeModel);
			Shopware()->Models()->flush();
		}

		$args->setReturn($orderVariables);

	}
}