Simplexml XPath的陌生人 [英] Simplexml XPath strangeness

问题描述

我正在编写一个读取和操作KML（xml）文档的脚本。以下是我正在阅读的文档的代码片段：

 <？xml version =1.0encoding =UTF- 8\" >？; 
<！ - 由功能操纵引擎2009（Build 5658）生成 - > 
< kml xmlns =http://earth.google.com/kml/2.2xmlns：atom =http://www.w3.org/2005/Atom> 
<文件> 
< name>南澳大利亚< / name> 
< visibility> 1< / visibility> 
< description><！[CDATA [Statistical Local Area 2008]]>< / description> 
< Folder id =kml_ft_SA_SLA08> 
< name> SA_SLA08< / name> 
< Placemark id =kml_1> 
< name> Mitcham（C） -  West< / name> 
< Style> 
<！ -  style info blah blah  - > 
< / Style> 
<多边形> 
<！ -  blah blah  - > 
< / Polygon> 
< / Placemark> 
 
<！ - 删除更多地标 - > 
< / Folder> 
< / Document> 
< / kml> 
  

我遇到的问题是使用XPath从中选择任何东西！

  $ doc = new DOMDocument（）; 
 $ doc-> load（'myfile.xml'）; //返回true 
 $ xp = new DOMXPath（$ doc）; 
 
 $ places = $ xp-> query（// Placemark）; 
 echo $ places-> length; //  - > 0 ?? !! ?? 
 $ everything = $ xp-> query（// *）; //（所以我知道XPath没有完全被borked）
 echo $ everything-> length; //  - > 2085 
  

这里发生了什么？

解决方案

 <？php 
 $ doc = new DOMDocument（） 
 $ doc-> load（'file.xml'）; //返回true 
 $ xp = new DOMXPath（$ doc）; 
 $ xp-> registerNamespace（'ge'，'http://earth.google.com/kml/2.2'）; 
 
 $ places = $ xp-> query（// ge：Placemark）; 
 echo $ places-> length; //  - > 0 ?? !! ?? 
 $ everything = $ xp-> query（// *）; //（所以我知道XPath没有完全被borked）
 
 // echo $ doc-> saveXML（）; 
  

显然，您必须注册'ge'命名空间并将其查询，至少这是什么几分钟后，我想起了。我想有时我们忘记我们在处理命名空间：p

I'm writing a script which reads and manipulates a KML (xml) document. Below is a snippet of the document I'm reading:

<?xml version="1.0" encoding="UTF-8"?>
<!-- Generated by Feature Manipulation Engine 2009 (Build 5658) -->
<kml xmlns="http://earth.google.com/kml/2.2" xmlns:atom="http://www.w3.org/2005/Atom">
    <Document>
        <name>South Australia</name>
        <visibility>1</visibility>
        <description><![CDATA[Statistical Local Area 2008]]></description>
        <Folder id="kml_ft_SA_SLA08">
            <name>SA_SLA08</name>
            <Placemark id="kml_1">
                <name>Mitcham (C) - West</name>
                <Style>
                    <!-- style info blah blah -->
                </Style>
                <Polygon>
                    <!-- blah blah -->
                </Polygon>
            </Placemark>

            <!-- snip lots more Placemarks -->
        </Folder>
    </Document>
</kml>

The problem I'm having is with using XPath to select anything from it!

$doc = new DOMDocument();
$doc->load('myfile.xml');    // returns true
$xp = new DOMXPath($doc);

$places = $xp->query("//Placemark");
echo $places->length;         // --> 0 ??!!??
$everything = $xp->query("//*"); // (so I know that the XPath isn't fully borked)
echo $everything->length;    // --> 2085 

What's going on here?

解决方案

<?php
$doc = new DOMDocument();
$doc->load('file.xml');    // returns true
$xp = new DOMXPath($doc);
$xp->registerNamespace('ge', 'http://earth.google.com/kml/2.2');

$places = $xp->query("//ge:Placemark");
echo $places->length;         // --> 0 ??!!??
$everything = $xp->query("//*"); // (so I know that the XPath isn't fully borked)

//echo $doc->saveXML();

Apparently you have to register the 'ge' namespace and query it as such, at least this is what I came up with after a few minutes googling. I guess sometimes we forget we're dealing with namespaces :p

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