当子值匹配时获取父数据

Question

I would like to get parent data when my child value matches with "id22"

<servers>
<someservers>
  <owner>id0</owner>
  <serverCode>fefwewf</serverCode>
  <address>345345</address>
  <authCertHash>efref</authCertHash>
  <authCertHash>erferf=</authCertHash>
  <client>id1</client>
  <client>id22</client>
</someservers>
<someservers>
  <owner>id33</owner>
  <serverCode>f</sewewefrverCode>
  <address>234234234</address>
  <authCertHash>sdfs</authCertHash>
  <client>id27</client>
</someservers>
</server>

Currently im trying as following:

$server = $xml -> xpath('//someservers//client='id22');
echo $server->address;

But it's not working, I get error:

Trying to get property of non-object in...

I hope to get output:

345345

Answer 1

SimpleXMLElement::xpath() only supports Xpath expressions that return an node list, so it can convert them into an array of SimpleXMLElementinstances.

@andersson already explained that you expression only returns the existence of the specified client element. You need to use a condition. This will return an array with matching SimpleXMLElement objects as the elements.

$servers = new SimpleXMLElement($xml);
$server = $servers->xpath('//someservers[client="id22"]')[0];
echo $server->address;

Output:

345345

DOMXpath::evaluate() is able to return the scalar value directly:

$document = new DOMDocument();
$document->loadXml($xml);
$xpath= new DOMXpath($document);
echo $xpath->evaluate('string(//someservers[client="id22"]/address)');