SimpleXML: How to parse nodenames including dots with xpath query

Question

I have to parse the following XML:

<BMECAT version="2005" xmlns="http://www.bmecat.org/bmecat/2005fd">
    <T_NEW_CATALOG prev_version="0">
        <PRODUCT>
            <NAME>Test</NAME>
            <USER_DEFINED_EXTENSIONS>
                <UDX.VENDOR.ATTRIBUTE lang="de">German</UDX.VENDOR.ATTRIBUTE>
                <UDX.VENDOR.ATTRIBUTE lang="en">English</UDX.VENDOR.ATTRIBUTE>
            </USER_DEFINED_EXTENSIONS>
        </PRODUCT>
    </T_NEW_CATALOG>
</BMECAT>

I need to get the value "German" via xpath. Everything I have tried so far didn't work so I need some help. I think the problem is that the tagname includes dots. I have found no way to escape the xpath expression.

Answer 1

The XML you show cannot be parsed because it is malformed (USER_DEFINED_EXTENSIONS is not closed properly). Assuming well-formed input, you could use DOMDocument instead of SimpleXML:

<?php
$xml = <<<'XML'
<BMECAT version="2005" xmlns="http://www.bmecat.org/bmecat/2005fd">
    <T_NEW_CATALOG prev_version="0">
        <PRODUCT>
            <NAME>Test</NAME>
            <USER_DEFINED_EXTENSIONS>
                <UDX.VENDOR.ATTRIBUTE lang="de">German</UDX.VENDOR.ATTRIBUTE>
                <UDX.VENDOR.ATTRIBUTE lang="en">English</UDX.VENDOR.ATTRIBUTE>
            </USER_DEFINED_EXTENSIONS>
        </PRODUCT>
    </T_NEW_CATALOG>
</BMECAT>
XML;

$dom = new DOMDocument();
$dom->loadXML($xml);

$xpath = new DOMXPath($dom);
$xpath->registerNamespace("bme",
        "http://www.bmecat.org/bmecat/2005fd");

$expression = 'string(
  /bme:BMECAT
  /bme:T_NEW_CATALOG
  /bme:PRODUCT
  /bme:USER_DEFINED_EXTENSIONS
  /bme:UDX.VENDOR.ATTRIBUTE[@lang = "de"]
)';

var_dump($xpath->evaluate($expression));

And the result will be

German

If you need to use SimpleXML, you really need to show your current PHP code.