How to stop looping in XML dom parsing PHP

Question

I have code something like this :

<?xml version="1.0" encoding="UTF-8"?>
<Personlist xmlns="http://example.org">
    <Person>
        <Name>Louis</Name>
        <Address>
            <StreetAddress>Somestreet</StreetAddress>
            <PostalCode>00001</PostalCode>
            <CountryName>Finland</CountryName>
        </Address>
    </Person>
    <Person>
        <Name>Rakshith</Name>
        <Address>
            <StreetAddress>Somestreet</StreetAddress>
            <PostalCode>00001</PostalCode>
            <CountryName>Finland</CountryName>
        </Address>
    </Person>
    <Person>
        <Name>Steve</Name>
        <Address>
            <StreetAddress>Someotherstreet</StreetAddress>
            <PostalCode>43400</PostalCode>
            <CountryName>Sweden</CountryName>
        </Address>
     </Person>
 </Personlist>

How to to stop looping if name 'Rakshith' found in xml dom parsing. And in simple xml parser we can directly access the nth element like $xml->Person[0]->Name. But in XML dom, we need to parse in foreach itself so far i know. Is there any way like this that would suit my requirement.

Thanks in advance

Answer 1

If you're are using DOM. You can use Xpath to select just the nodes you want to iterate:

$dom = new DOMDocument();
$dom->loadXml($xml);
$xpath = new DOMXpath($dom);
$xpath->registerNamespace('ns1', 'http://example.org');

$persons = $xpath->evaluate('/ns1:Personlist/ns1:Person[ns1:Name = "Rakshith"]');
foreach ($persons as $person) {
  var_dump(
    $xpath->evaluate('string(ns1:Name)', $person),
    $xpath->evaluate('string(ns1:Address/ns1:CountryName)', $person)
  );
}

Output: https://eval.in/110336

string(8) "Rakshith"
string(7) "Finland"

Xpath is quite powerful. You're using expression with conditions to describe a list of nodes (that can be a list with a single node or an empty list, too). If you do something that implies a scalar value the first node in the list is used.

I you example, you define a default XML namespace. Here ist no default XML namespace in xpath, you register your own prefix and use it. The example uses "ns1".

The Xpath expression selects the Personlist document element

/ns1:Personlist

then its Person child elements:

/ns1:Personlist/ns1:Person

limits that list to nodes with a child Name with the the value "Rakshith"

/ns1:Personlist/ns1:Person[ns1:Name = "Rakshith"]

This will always return a list (an empty one if nothing is found) so it it possible to iterate that list without further validation.

Inside the loop expression are used with a context, provided as the second argument to evaluate. The string() function casts the result list into a string value.