access php simplexml with namespaces - php

Question

-
Hello Everyone,
I'm trying to access data in a XML file:
<OAI-PMH xmlns="http://www.openarchives.org/OAI/2.0/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:dc="http://dublincore.org/documents/dcmi- namespace/" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/ http://www.openarchives.org/OAI/2.0/OAI-PMH.xsd";>
<responseDate>2013-04-15T12:14:31Z</responseDate>
<ListRecords>
<record>
<header>
<identifier>
a1b31ab2-9efe-11df-9922-efbb156aa6c1:01442b82-59a4-627e-800f-c63de74fc109
</identifier>
<datestamp>2012-08-16T14:42:52Z</datestamp>
</header>
<metadata>
<oai_dc:dc xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/oai_dc/ http://www.openarchives.org/OAI/2.0/oai_dc.xsd";>
<dc:description>...</dc:description>
<dc:date>1921</dc:date>
<dc:identifier>K11510</dc:identifier>
<dc:source>Waterschap Vallei & Eem</dc:source>
<dc:source>...</dc:source>
<dc:source>610</dc:source>
<dc:coverage>Bunschoten</dc:coverage>
<dc:coverage>Veendijk</dc:coverage>
<dc:coverage>Spakenburg</dc:coverage>
</oai_dc:dc>
</metadata>
<about>...</about>
</record>
This a a example of the XML.
I need to access data like dc:date dc:source etc.
Anyone any ideas?
Best regards,
Tim
-- UPDATE --
I'm now trying this:
foreach( $xml->ListRecords as $records )
{
foreach( $records AS $record )
{
$data = $record->children( 'http://www.openarchives.org/OAI/2.0/oai_dc/' );
$rows = $data->children( 'http://purl.org/dc/elements/1.1/' );
echo $rows->date;
break;
}
break;
}

Answer 1

You have nested elements that are in different XML namespaces. In concrete you have got two additional namespaces involved:
$nsUriOaiDc = 'http://www.openarchives.org/OAI/2.0/oai_dc/';
$nsUriDc = 'http://purl.org/dc/elements/1.1/';
The first one is for the <oai_dc:dc> element which contains the second ones * <dc:*>* elements like <dc:description> and so on. Those are the elements you're looking for.
In your code you already have a good nose how this works:
$data = $record->children( 'http://www.openarchives.org/OAI/2.0/oai_dc/' );
$rows = $data->children( 'http://purl.org/dc/elements/1.1/' );
However there is a little mistake: the $data children are not children of $record but of $record->metadata.
You also do not need to nest two foreach into each other. The code example:
$nsUriOaiDc = 'http://www.openarchives.org/OAI/2.0/oai_dc/';
$nsUriDc = 'http://purl.org/dc/elements/1.1/';
$records = $xml->ListRecords->record;
foreach ($records as $record)
{
$data = $record->metadata->children($nsUriOaiDc);
$rows = $data->children($nsUriDc);
echo $rows->date;
break;
}
/** output: 1921 **/
If you are running into problems like these, you can make use of $record->asXML('php://output'); to show which element(s) you are currently traversing to.

Answer 2

I think this is what you're looking for. Hope it helps ;)

Answer 3

use DomDocument for this like access to dc:date
$STR='
<OAI-PMH xmlns="http://www.openarchives.org/OAI/2.0/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:dc="http://dublincore.org/documents/dcmi- namespace/" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/ http://www.openarchives.org/OAI/2.0/OAI-PMH.xsd";>
<responseDate>2013-04-15T12:14:31Z</responseDate>
<ListRecords>
<record>
<header> <identifier> a1b31ab2-9efe-11df-9922-efbb156aa6c1:01442b82-59a4-627e-800f-c63de74fc109 </identifier>
<datestamp>2012-08-16T14:42:52Z</datestamp>
</header>
<metadata>
<oai_dc:dc xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/oai_dc/ http://www.openarchives.org/OAI/2.0/oai_dc.xsd";>
<dc:description>...</dc:description>
<dc:date>1921</dc:date>
<dc:identifier>K11510</dc:identifier>
<dc:source>Waterschap Vallei & Eem</dc:source>
<dc:source>...</dc:source>
<dc:source>610</dc:source>
<dc:coverage>Bunschoten</dc:coverage>
<dc:coverage>Veendijk</dc:coverage>
<dc:coverage>Spakenburg</dc:coverage>
</oai_dc:dc>
</metadata>
<about>...</about>
</record>';
$dom= new DOMDocument;
$STR= str_replace("&", "&", $STR); // disguise &s going IN to loadXML()
// $dom->substituteEntities = true; // collapse &s going OUT to transformToXML()
$dom->recover = TRUE;
#$dom->loadHTML('<?xml encoding="UTF-8">' .$STR);
// dirty fix
foreach ($dom->childNodes as $item)
if ($item->nodeType == XML_PI_NODE)
$dom->removeChild($item); // remove hack
$dom->encoding = 'UTF-8'; // insert proper
print_r($doc->getElementsByTagName('dc')->item(0)->getElementsByTagName('date')->item(0)->textContent);
output:
1921
or access to dc:source
$source= $doc->getElementsByTagName('dc')->item(0)->getElementsByTagName('source');
foreach($source as $value){
echo $value->textContent."\n";
}
output:
Waterschap Vallei & Eem
...
610
or give you array
$array=array();
$source= $doc->getElementsByTagName('dc')->item(0)->getElementsByTagName("*");
foreach($source as $value){
$array[$value->localName][]=$value->textContent."\n";
}
print_r($array);
output:
Array
(
[description] => Array
(
[0] => ...
)
[date] => Array
(
[0] => 1921
)
[identifier] => Array
(
[0] => K11510
)
[source] => Array
(
[0] => Waterschap Vallei & Eem
[1] => ...
[2] => 610
)
[coverage] => Array
(
[0] => Bunschoten
[1] => Veendijk
[2] => Spakenburg
)
)

Answer 4

Using XPath makes dealing with namespaces more straightforward:
<?php
// load the XML into a DOM document
$doc = new DOMDocument;
$doc->load('oai-response.xml'); // or use $doc->loadXML($xml) for an XML string
// bind the DOM document to an XPath object
$xpath = new DOMXPath($doc);
// map all the XML namespaces to prefixes, for use in XPath queries
$xpath->registerNamespace('oai', 'http://www.openarchives.org/OAI/2.0/');
$xpath->registerNamespace('oai_dc', 'http://www.openarchives.org/OAI/2.0/oai_dc/');
$xpath->registerNamespace('dc', 'http://purl.org/dc/elements/1.1/');
// identify each record using an XPath query
// collect data as either strings or arrays of strings
foreach ($xpath->query('oai:ListRecords/oai:record/oai:metadata/oai_dc:dc') as $item) {
$data = array(
'date' => $xpath->evaluate('string(dc:date)', $item), // $item is the context for this query
'source' => array(),
);
foreach ($xpath->query('dc:source', $item) as $source) {
$data['source'][] = $source->textContent;
}
print_r($data);
}