PHP SimpleXML 子节点数据提取

我一直在尝试使用 foreach 循环提取节点数据的子级。我可以毫无问题地获取主节点数据，但子数据只获取第一个数据集然后重复。有人可以告诉我我做错了什么吗？我从官方文档中得到了示例：http://php.net/manual/en/simplexmlelement.children.php

这是我的测试 xml

<Result>
<Result_Data>
    <Root_XML>
        <Stock>
            <Stock_Code>28</Stock_Code>
            <Barcode>28</Barcode>
            <Multiple_Barcodes>
                <Barcode>BARCODE1</Barcode>
                <Barcode>BARCODE2</Barcode>
            </Multiple_Barcodes>
            <Sell_Prices>
                <Sell_Price>
                    <Inclusive>10</Inclusive>
                    <Exclusive>8.77193</Exclusive>
                </Sell_Price>
                <Sell_Price>
                    <Inclusive>0</Inclusive>
                    <Exclusive>0</Exclusive>
                </Sell_Price>
                <Sell_Price>
                    <Inclusive>0</Inclusive>
                    <Exclusive>0</Exclusive>
                </Sell_Price>
            </Sell_Prices>
            <New_Prices>
                <New_Price>0</New_Price>
                <New_Price>0</New_Price>
                <New_Price>0</New_Price>
                <New_Price>0</New_Price>
            </New_Prices>
            <Work_In_Progress_Quantity>0</Work_In_Progress_Quantity>
            <Extended_Description />
            <Onhand>0</Onhand>
        </Stock>
        <Stock>
            <Stock_Code>123</Stock_Code>
            <Barcode>123</Barcode>
            <Multiple_Barcodes>
                <Barcode>BARCODE123</Barcode>
                <Barcode>BARCODE124</Barcode>
            </Multiple_Barcodes>
            <Sell_Prices>
                <Sell_Price>
                    <Inclusive>10</Inclusive>
                    <Exclusive>8.77193</Exclusive>
                </Sell_Price>
                <Sell_Price>
                    <Inclusive>0</Inclusive>
                    <Exclusive>0</Exclusive>
                </Sell_Price>
                <Sell_Price>
                    <Inclusive>0</Inclusive>
                    <Exclusive>0</Exclusive>
                </Sell_Price>
            </Sell_Prices>
            <New_Prices>
                <New_Price>0</New_Price>
                <New_Price>0</New_Price>
                <New_Price>0</New_Price>
                <New_Price>0</New_Price>
            </New_Prices>
            <Work_In_Progress_Quantity>0</Work_In_Progress_Quantity>
            <Extended_Description />
            <Onhand>0</Onhand>
        </Stock>            
    </Root_XML>
</Result_Data>

这是我的php代码

$file = file_get_contents('play.xml', true);  
$XMLtoSAVE = new SimpleXMLElement($file);
foreach ($XMLtoSAVE->Result_Data->Root_XML->Stock as $element) {
echo $element->Stock_Code . "'n";
    //Child Node Data - Barcode
    foreach ($XMLtoSAVE->Result_Data->Root_XML->Stock->Multiple_Barcodes as $element) {
    echo $element->Barcode . "'n";
    }

}   

这是输出：

28

BARCODE1

123

BARCODE1

预期输出：

28

BARCODE1

BARCODE2

123

BARCODE123

BARCODE124