magento 购物车页面 更新添加 custom option

//首先取得产品所有option，通过title检索出指定optionID
$test = $_item->getProduct()->getProductOptionsCollection();
foreach($test as $t){
    if($t->getTitle() == 'Special Requirement'){
        $sr_optionid = $t->getOptionId();
    }
}

//form  $sr_value在循环输出option时赋值
<?php if(!empty($sr_optionid)):?>
<div style="clear:both;">Special Requirement: <textarea name="cart[<?php echo $_item->getId();?>][sr_content]" cols="50"><?php echo $sr_value;?></textarea>
<input type="hidden" name="cart[<?php echo $_item->getId();?>][sr_id]" value="<?php echo $sr_optionid;?>"/>
</div>
<?php endif;?>

//app/code/core/Mage/Checkout/Model/Cart.php
public function updateItems($data)
{
...
if(isset($itemInfo['sr_content']) && !empty($itemInfo['sr_content']) && isset($itemInfo['sr_id'])){
    $itemInQuote->addOption(array(
        'code'  => 'option_'.$itemInfo['sr_id'],
        'value' => $itemInfo['sr_content']
    ));
    $old_ids = $itemInQuote->getOptionByCode('option_ids');
    if($old_ids){//已经有的option
        $old_ids_v = $old_ids->getValue();
        if(stripos($old_ids_v,$itemInfo['sr_id'])===false){
            $itemInQuote->addOption(array(
                'code'  => 'option_ids',
                'value' => $old_ids_v.','.$itemInfo['sr_id']//！！！合并处理
            ));
        }
    }else{
        $itemInQuote->addOption(array(
            'code'  => 'option_ids',
            'value' => $itemInfo['sr_id']
        ));
    }
}
...
}