PHP: get values from node by name (problems with namespaces) - php

Question

I received these xml from external services:
<?xml version="1.0" encoding="UTF-8"?>
<?xml-stylesheet type="text/xsl" href=(...)?>
<pos:Document xmlns:pos=(...) xmlns:str=(...) xmlns:xsi=(...) xsi:schemaLocation=(...)>
<pos:DescribeDocument>
(...)
</pos:DescribeDocument>
<pos:UPP>
(...)
</pos:UPP>
<ds:Signature Id="ID-9326" xmlns:ds="http://www.w3.org/2000/09/xmldsig#">
<ds:SignedInfo Id="ID-9325" xmlns:ds="http://www.w3.org/2000/09/xmldsig#" xmlns:pos="adress" xmlns:str="adress" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
(...)
</ds:SignedInfo>
<ds:Object>
<xades:QualifyingProperties Id="ID-9337a6d1" Target="#ID-932668c0-d4f9-11e3-bb2d-001a645ad128" xmlns:xades="http://uri.etsi.org/01903/v1.3.2#">
<xades:SignedProperties Id="ID-9337a6d0" xmlns:ds="http://www.w3.org/2000/09/xmldsig#" xmlns:pos="adress" xmlns:str="adress" xmlns:xades="adress" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<xades:SignedSignatureProperties>
<xades:SigningTime>sometime</xades:SigningTime>
<xades:SigningCertificate>
<xades:Cert>
<xades:CertDigest>
<ds:DigestMethod Algorithm="adress"/>
<ds:DigestValue>someValue</ds:DigestValue>
</xades:CertDigest>
<xades:IssuerSerial>
<ds:X509IssuerName>CNsomeValue</ds:X509IssuerName>
<ds:X509SerialNumber>SerialsomeValue</ds:X509SerialNumber>
</xades:IssuerSerial>
</xades:Cert>
</xades:SigningCertificate>
<xades:SignaturePolicyIdentifier>
<xades:SignaturePolicyImplied/>
</xades:SignaturePolicyIdentifier>
</xades:SignedSignatureProperties>
<xades:SignedDataObjectProperties>
<xades:DataObjectFormat ObjectReference="#ID-93257e60">
<xades:Description>NEEDVALUE</xades:Description>
</xades:DataObjectFormat>
</xades:SignedDataObjectProperties>
</xades:SignedProperties>
</xades:QualifyingProperties>
</ds:Object>
</ds:Signature>
</pos:Document>
It's have a few namespace. And I have to get value in value.
I wrote a some code but nothing works:
$xmlFileContent = file_get_contents($pathToXML);
$dom = new SimpleXMLElement($xmlFileContent, LIBXML_COMPACT);
$namespaces = $dom->getNamespaces(true);
foreach ($namespaces as $key => $namespace) {
$dom->registerXPathNamespace($key, $namespace);
}
$matches = $dom->xpath('//xades:Description'); //no success
and
$doms = new DOMDocument;
$doms->loadXML($path);
foreach($doms->getElementsByTagNameNS($namespaces['xades'],'*') as $element){
echo 'local name: ', $element->localName, ', prefix: ', $element->prefix, "\n"; //no success
}
Can you help me to get to these node (xades:Description)?
PS:
i used it too (but no success):
$result1 = $dom->xpath('/Dokument/ds:Signature/ds:Object/xades:QualifyingProperties/xades:SignedProperties/xades:SignedDataObjectProperties/xades:DataObjectFormat/xades:Description');

Answer 1

You removed the namespace definitions from your XML. If you see an attribute like 'xmlns:xades' the actual namespace is the value of that attribute. It defines an alias/prefix for that namespace in the current context. Most of the time URLs are used as namespace identifiers (because it avoids potential conflicts). But a value like urn:somestring is valid.
You need to register a prefix for the namespace on the DOMXpath object, too. This prefix does not need to be identical to the one in the document. Look at it this way:
DOMDocument resolves a node name from prefix:Description to {namespace-uri}:Description.
DOMXpath resolves the node names in the Xpath expressions the same way using its own definition. For example //prefix:Description to //{namespace-uri}:Description. Then it compares the resolved names.
$dom = new DOMDocument();
$dom->loadXml($xml);
$xpath = new DOMXpath($dom);
$xpath->registerNamespace('x', 'urn:xades');
var_dump($xpath->evaluate('string(//x:Description)'));
Output: https://eval.in/181304
string(9) "NEEDVALUE"

Answer 2

There is possible workaround by modifying your XPath to ignore namespaces, just in case you can't find proper solution :
$result = $dom->xpath('//*[local-name() = "Description"]');