如何更改XML节点值？

Question

我已经回顾了很多有关此主题的帖子，并尝试对我的代码进行调整但似乎无法使其正常工作，我们非常感谢任何帮助。

如何更新cen_inst_units_z_name的值？

XML

<?xml version="1.0" encoding="UTF-8" ?> 
<xfa:data xmlns:xfa="http://www.xfa.org/schema/xfa-data/1.0/">
    <form1>
          <cen_inst_units_z_name>Department of School</cen_inst_units_z_name>
    </form1>
</xfa:data>   

PHP

<?php 
    $doc = new DOMDocument();
    $doc->load('52500_data.xml');
    $xpath = new DOMXPath($doc);

    $parent = $doc->getElementsByTagName('form1')->item(0);
    $query = $xpath->query('cen_inst_units_z_name',$parent);

    //Checked to make sure I was pulling the correct node
    echo $query->item(0)->textContent;

    $query->item(0)->nodeValue = 'Test123'; 
    $doc->saveXML();
?>

Answer 1

我更改了代码以保存新文档并获得了我想要的结果：

$doc->save("newdoc.xml");