Why does SimpleXML XPath return an empty array?

Question

I've the following XML-File:

<SyncCustomerPartyMaster xmlns="http://schema.infor.com/InforOAGIS/2" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xsi:schemaLocation="http://schema.infor.com/InforOAGIS/2 http://schema.infor.com/2.9.1/InforOAGIS/BODs/Developer/SyncCustomerPartyMaster.xsd" releaseID="9.2" versionID="2.9.1">
    <ApplicationArea>
        <Sender>
            <LogicalID>lid://infor.ln.dach_nausveln1_200</LogicalID>
            <ComponentID>erp</ComponentID>
            <ConfirmationCode>OnError</ConfirmationCode>
        </Sender>
        <CreationDateTime>2014-10-09T13:47:48Z</CreationDateTime>
    </ApplicationArea>
    <DataArea>
        <Sync>
            <TenantID>infor</TenantID>
            <AccountingEntityID>200</AccountingEntityID>
            <LocationID/>
            <ActionCriteria>
            <ActionExpression actionCode="Add"/>
            </ActionCriteria>
        </Sync>
        <CustomerPartyMaster>
            <PartyIDs>
                <ID accountingEntity="200" lid="lid://infor.ln.dach_nausveln1_200" variationID="108">10100</ID>
                <DisplayID>10100</DisplayID>
            </PartyIDs>
        </CustomerPartyMaster>
    </DataArea>
</SyncCustomerPartyMaster>

And I'm trying to access the DisplayId via XPath: '/SyncCustomerPartyMaster/DataArea/CustomerPartyMaster/PartyIDs/DisplayID'

<?php
    $xml = simplexml_load_file("example.xml");
    $displayId = $xml->xpath('/SyncCustomerPartyMaster/DataArea/CustomerPartyMaster/PartyIDs/DisplayID');

    print_r($xml);

    echo '<br />';
    echo '<br />';

    print_r($displayId);

?>

But print_r($display_id) just returns an empty array. I fiddled around a bit with registerXPathNamespace]1 which did not do the trick - can anyone please point me into the right direction?

score 3 · Accepted Answer · answered Oct 09 '14 at 17:18

xmlns="http://schema.infor.com/InforOAGIS/2"

This declares a default namespace which you do need to register via registerXPathNamespace() and address the elements using the prefix registered.

Example:

$xml = simplexml_load_file("example.xml");
$xml->registerXPathNamespace('ns', "http://schema.infor.com/InforOAGIS/2");
$displayIds = $xml->xpath('/ns:SyncCustomerPartyMaster/ns:DataArea/ns:CustomerPartyMaster/ns:PartyIDs/ns:DisplayID');

foreach ($displayIds as $displayId) {
    echo $displayId;
}

Why does SimpleXML XPath return an empty array?

1 Answers1

Example:

Output: