为什么 XPath 找不到标签？

Question

我有xml文件和PHP脚本来处理这个XML。为什么脚本找不到标签？为什么 xpath 失败并显示警告：

PHP Warning:  DOMXPath::query(): Invalid predicate in test.php on line 7
PHP Warning:  DOMXPath::query(): Invalid expression in test.php on line 7
PHP Warning:  Invalid argument supplied for foreach() in test.php on line 9

医生.xml

<?xml version="1.0" encoding="UTF-8"?>
<rootTag>
<div id="tag-id"></div>
<div id="tag-id"></div>
<div id="tag-id"></div>
<div id="tag-id"></div>
<div id="tag-id"></div>
</rootTag>

测试.php

<?php
$doc = new DOMDocument();
$doc->load('./doc.xml');
$xpath = new DOMXPath($doc);
$tags = $xpath->query('//div[@id="tag-id"');
foreach ($tags as $node) {
print($node->nodeName);
}
?>

Answer 1

好吧，您的查询几乎是正确的。你刚刚忘记了把最后关闭"]" 字符。

它应该是：

$tags = $xpath->query('//div[@id="tag-id"]');

相反：

$tags = $xpath->query('//div[@id="tag-id"');