Using PHP SimpleXML to access non-default namespace element attributes - php

Question

I have some annoying XML from an API response that looks like:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?><report><QueryResult>
<ResumptionToken>123456</ResumptionToken>
<IsFinished>true</IsFinished>
<ResultXml>
<rowset xmlns="urn:schemas-microsoft-com:xml-analysis:rowset">
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:saw-sql="urn:saw-sql" targetNamespace="urn:schemas-microsoft-com:xml-analysis:rowset">
<xsd:complexType name="Row">
<xsd:sequence>
<xsd:element maxOccurs="1" minOccurs="1" name="Column0" saw-sql:aggregationRule="none" saw-sql:aggregationType="nonAgg" saw-sql:columnHeading="0" saw-sql:displayFormula="0" saw-sql:length="4" saw-sql:precision="12" saw-sql:scale="0" saw-sql:tableHeading="" saw-sql:type="integer" type="xsd:int"/>
<xsd:element maxOccurs="1" minOccurs="0" name="Column1" saw-sql:aggregationRule="none" saw-sql:aggregationType="nonAgg" saw-sql:columnHeading="ISBN" saw-sql:displayFormula=""Bibliographic Details"."ISBN"" saw-sql:length="255" saw-sql:precision="255" saw-sql:scale="0" saw-sql:tableHeading="Bibliographic Details" saw-sql:type="varchar" type="xsd:string"/>
<xsd:element maxOccurs="1" minOccurs="0" name="Column2" saw-sql:aggregationRule="none" saw-sql:aggregationType="nonAgg" saw-sql:columnHeading="ISSN" saw-sql:displayFormula=""Bibliographic Details"."ISSN"" saw-sql:length="255" saw-sql:precision="255" saw-sql:scale="0" saw-sql:tableHeading="Bibliographic Details" saw-sql:type="varchar" type="xsd:string"/>
<xsd:element maxOccurs="1" minOccurs="0" name="Column3" saw-sql:aggregationRule="none" saw-sql:aggregationType="nonAgg" saw-sql:columnHeading="Publication Date" saw-sql:displayFormula=""Bibliographic Details"."Publication Date"" saw-sql:length="255" saw-sql:precision="255" saw-sql:scale="0" saw-sql:tableHeading="Bibliographic Details" saw-sql:type="varchar" type="xsd:string"/>
</xsd:sequence>
</xsd:complexType>
</xsd:schema>
<Row>
<Column0>0</Column0>
<Column1>55555555 444444445</Column1>
<Column3>[2019]</Column3>
</Row>
<Row>
<Column0>0</Column0>
<Column1>555555555</Column1>
<Column3>©2009.</Column3>
</Row>
I'm using PHP's SimpleXML to parse this data, but am struggling to access the column headers located in the non-default namespace under xsd:element. For example, I need to access the value: saw-sql:columnHeading="Publication Date", as this column can be dynamic and isn't always "Publication Date". So I'm looking to pluck out the values for saw-sql[#columnHeading].
I've tried all manners of registering the namespaces with Xpath, using attributes() etc etc. The closest I got was:
$ResponseXml->registerXPathNamespace('xsd','http://www.w3.org/2001/XMLSchema');
$elements = $ResponseXml->xpath('//xsd:element[#minOccurs]');
This actually got me the default namespace attributes, but I need the ones for saw-sql, and the same method of:
$ResponseXml->registerXPathNamespace('saw-sql','urn:saw-sql');
$elements = $ResponseXml->xpath('//saw-sql:element[#columnHeading]');
does not get me any results.

Answer 1

Your XPath //saw-sql:element[#columnHeading] is looking for elements named element (in the saw-sql namespace), which have attributes named columnHeading (in no namespace), but the element names are actually in the xsd namespace, while the attributes are in the saw-sql namespace.
So I believe what you want is:
$ResponseXml->registerXPathNamespace('xsd','http://www.w3.org/2001/XMLSchema');
$ResponseXml->registerXPathNamespace('saw-sql','urn:saw-sql');
$elements = $ResponseXml->xpath('//xsd:element[#saw-sql:columnHeading]');

Answer 2

fwiw you could use DOMDocument to parse it instead of SimpleXML, for example
<?php
$xml = <<<'XML'
<?xml version="1.0" encoding="UTF-8" standalone="yes"?><report><QueryResult>
<ResumptionToken>123456</ResumptionToken>
<IsFinished>true</IsFinished>
<ResultXml>
<rowset xmlns="urn:schemas-microsoft-com:xml-analysis:rowset">
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:saw-sql="urn:saw-sql" targetNamespace="urn:schemas-microsoft-com:xml-analysis:rowset">
<xsd:complexType name="Row">
<xsd:sequence>
<xsd:element maxOccurs="1" minOccurs="1" name="Column0" saw-sql:aggregationRule="none" saw-sql:aggregationType="nonAgg" saw-sql:columnHeading="0" saw-sql:displayFormula="0" saw-sql:length="4" saw-sql:precision="12" saw-sql:scale="0" saw-sql:tableHeading="" saw-sql:type="integer" type="xsd:int"/>
<xsd:element maxOccurs="1" minOccurs="0" name="Column1" saw-sql:aggregationRule="none" saw-sql:aggregationType="nonAgg" saw-sql:columnHeading="ISBN" saw-sql:displayFormula=""Bibliographic Details"."ISBN"" saw-sql:length="255" saw-sql:precision="255" saw-sql:scale="0" saw-sql:tableHeading="Bibliographic Details" saw-sql:type="varchar" type="xsd:string"/>
<xsd:element maxOccurs="1" minOccurs="0" name="Column2" saw-sql:aggregationRule="none" saw-sql:aggregationType="nonAgg" saw-sql:columnHeading="ISSN" saw-sql:displayFormula=""Bibliographic Details"."ISSN"" saw-sql:length="255" saw-sql:precision="255" saw-sql:scale="0" saw-sql:tableHeading="Bibliographic Details" saw-sql:type="varchar" type="xsd:string"/>
<xsd:element maxOccurs="1" minOccurs="0" name="Column3" saw-sql:aggregationRule="none" saw-sql:aggregationType="nonAgg" saw-sql:columnHeading="Publication Date" saw-sql:displayFormula=""Bibliographic Details"."Publication Date"" saw-sql:length="255" saw-sql:precision="255" saw-sql:scale="0" saw-sql:tableHeading="Bibliographic Details" saw-sql:type="varchar" type="xsd:string"/>
</xsd:sequence>
</xsd:complexType>
</xsd:schema>
<Row>
<Column0>0</Column0>
<Column1>55555555 444444445</Column1>
<Column3>[2019]</Column3>
</Row>
<Row>
<Column0>0</Column0>
<Column1>555555555</Column1>
<Column3>©2009.</Column3>
</Row>
XML;
$domd = new DOMDocument();
#$domd->loadHTML($xml);
foreach ($domd->getElementsByTagName(strtolower("ResultXml")) as $resultXml) {
$keyNames1 = [];
$keyNames2 = [];
foreach ($resultXml->getElementsByTagName("rowset") as $rowset) {
foreach ($rowset->getElementsByTagName("sequence") as $sequence) {
foreach ($sequence->getElementsByTagName("element") as $element) {
$keyNames1[] = $element->getAttribute("name");
$keyNames2[] = $element->getAttribute(strtolower("saw-sql:columnHeading"));
}
}
}
$rows = [];
foreach ($resultXml->getElementsByTagName("row") as $row) {
$rowData = [];
foreach ($keyNames1 as $keyName1Key => $keyName1Name) {
$tmp = $row->getElementsByTagName(strtolower($keyName1Name));
if ($tmp->length) {
$rowData[$keyNames2[$keyName1Key]] = $tmp->item(0)->textContent;
}
}
$rows[] = $rowData;
}
var_export($rows);
}
yields
array (
0 =>
array (
0 => '0',
'ISBN' => '55555555 444444445',
'Publication Date' => '[2019]',
),
1 =>
array (
0 => '0',
'ISBN' => '555555555',
'Publication Date' => '©2009.',
),
)
i used loadHTML instead of loadXML because DOMDocument insists that your XML is not valid XML; in loadHTML() mode, everything is lowercase for some reason, in loadXML() everything is case-sensitive.

Answer 3

SimpleXMLElement::attributes() allows you to access the attributes of a specific namespace providing the namespace URI as a parameter.
$value = $simpleXMLElement->attributes($namespaceURI);
But first I would suggest defining a constant (or variable) for the namespaces that you are using. This will make your code a lot more readable and avoid typos.
Be aware that "rowset" redefines the default namespace for itself and the descendant element nodes, they are not in the "empty/none" namespace.
// define a dictionary for the namespaces
const XMLNS = [
// same alias as in the document
'xsd' => 'http://www.w3.org/2001/XMLSchema',
// let's use a shorter alias
'saw' => 'urn:saw-sql',
// own alias - used without alias in the document
'rowset' => 'urn:schemas-microsoft-com:xml-analysis:rowset'
];
$report = new SimpleXMLElement(getXMLString());
foreach (XMLNS as $alias => $uri) {
$report->registerXpathNamespace($alias, $uri);
}
$columns = [];
foreach($report->xpath('//xsd:complexType[#name="Row"]/xsd:sequence/xsd:element') as $element) {
$columns[] = [
// read the attribute (fallback to '' if missing), cast to string
'name'=> (string)($element['name'] ?? ''),
// read attribute with namespace
'heading'=> (string)($element->attributes(XMLNS['saw'])['columnHeading'] ?? '')
];
}
var_dump($columns);
Output:
array(4) {
[0]=>
array(2) {
["name"]=>
string(7) "Column0"
["heading"]=>
string(1) "0"
}
[1]=>
array(2) {
["name"]=>
string(7) "Column1"
["heading"]=>
string(4) "ISBN"
}
[2]=>
array(2) {
["name"]=>
string(7) "Column2"
["heading"]=>
string(4) "ISSN"
}
[3]=>
array(2) {
["name"]=>
string(7) "Column3"
["heading"]=>
string(16) "Publication Date"
}
}
The Xpath Expression
Fetch the type definitions: //xsd:complexType
Filter for "Row": //xsd:complexType[#name="Row"]
The elements inside the sequence:
//xsd:complexType[#name="Row"]/xsd:sequence/xsd:element
The part in [] are conditions for nodes returned the previous location path. So //foo[#bar] would return the foo element nodes with a bar attribute, while //foo/#bar would return the bar attributes of all foo element nodes.
DOM
This solution would not look much different with DOM. The Xpath processor is a separate object and here are specific methods to work with namespaces (suffix "NS"). DOM is more specific and powerful then SimpleXML.
$document = new DOMDocument();
$document->loadXML(getXMLString());
$xpath = new DOMXpath($document);
foreach (XMLNS as $alias => $uri) {
$xpath->registerNamespace($alias, $uri);
}
$columns = [];
foreach($xpath->evaluate('//xsd:complexType[#name="Row"]/xsd:sequence/xsd:element') as $element) {
$columns[] = [
'name'=> $element->getAttribute('name'),
'heading'=> $element->getAttributeNS(XMLNS['saw'], 'columnHeading')
];
}
var_dump($columns);