DOMXPath::__construct
Note that this method does not provide any means to distinguish between a successful result that returns FALSE and an error.
For example, this will succeed and return FALSE:
<?php $xpath->evaluate("1 = 0"); ?>
One workaround when you know you are expecting a Boolean is to wrap the result with string(). e.g.
<?php $xpath->evaluate("string(1 = 0)"); ?>
This will return a string "false" on success, or the Boolean FALSE on error.
DOMXPath::evaluate
(PHP 5 >= 5.1.0)
DOMXPath::evaluate — Évalue une expression XPath donnée et retourne un résultat écrit si possible
Description
public mixed DOMXPath::evaluate
( string $expression
[, DOMNode $contextnode
[, bool $registerNodeNS = true
]] )
Exécute l'expression XPath expression et retourne un résultat écrit si possible.
Liste de paramètres
- expression
-
L'expression XPath à exécuter.
- contextnode
-
Le paramètre optionnel contextnode peut être spécifié pour effectuer des requêtes XPath relatives. Par défaut, les requêtes sont relatives à l'élément root.
- registerNodeNS
-
Le paramètre optionnel registerNodeNS peut être renseigné pour désactiver l'enregistrement automatique du noeud de contexte.
Valeurs de retour
Retourne un résultat écrit si possible ou un DOMNodeList contenant tous les noeuds correspondant à 'expression XPath expression.
Si le paramètre expression est mal formé ou bien si le paramètre contextnode est invalide, la méthode DOMXPath::evaluate() retournera FALSE.
Historique
| Version | Description |
|---|---|
| 5.3.3 | Ajout du paramètre registerNodeNS. |
Exemples
Exemple #1 Récupération du nombre total de livres anglais
<?php
$doc = new DOMDocument;
$doc->load('book.xml');
$xpath = new DOMXPath($doc);
$tbody = $doc->getElementsByTagName('tbody')->item(0);
// notre requête est relative au noeud tbody
$query = 'count(row/entry[. = "en"])';
$entries = $xpath->evaluate($query, $tbody);
echo "Il y a $entries livres anglais\n";
?>
L'exemple ci-dessus va afficher :
Il y a 2 livres anglais
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User Contributed Notes
DOMXPath::evaluate
daniel at danielnorton dot com
25-Jun-2011 11:56
Damien Bezborodov
28-Mar-2011 08:13
If your expression returns a node set, you will get a DOMNodeList instead of a typed result. Instead, try modifying your expression from "//node[1]" to "string(//node[1])".
daniel ad demus dk
16-Jun-2008 05:02
It seems this method is only included from PHP 5.1.
yuriucsal at NOSPAM dot yahoo dot com dot br
06-Mar-2005 01:55
this class can substitute the method evaluate while it is not validated. Made for Yuri Bastos and Jo�o Gilberto Magalh�es.
<?php
class XPtahQuery
{
// function returns a DOMNodeList from a relative xPath
public static function selectNodes($pNode, $xPath)
{
$pos = strpos(self::getFullXpath($pNode),"/",1);
$xPathQuery = substr(self::getFullXpath($pNode),$pos);//to paste /#document[1]/
$xPathQueryFull = $xPathQuery. $xPath;
$domXPath = new DOMXPath($pNode->ownerDocument);
$rNodeList = $domXPath->query($xPathQueryFull);
return $rNodeList;
}
// function returns a DOMNode from a xPath from other DOMNode
public static function selectSingleNode($pNode, $xPath)
{
$pos = strpos(self::getFullXpath($pNode),"/",1);
$xPathQuery = substr(self::getFullXpath($pNode),$pos);//to paste /#document[1]/
$xPathQueryFull = $xPathQuery. $xPath;
$domXPath = new DOMXPath($pNode->ownerDocument);
$rNode = $domXPath->query($xPathQueryFull)->item(0);
return $rNode;
}
//utilitaries functions off selectSingleNode
private function getNodePos($pNode, $nodeName)
{
if($pNode == null)
{
return 0;
}
else
{
$var = 0;
if ($pNode->previousSibling != null)
{
if ($pNode->previousSibling->nodeName == $nodeName)
{
$var = 1;
}
}
return self::getNodePos($pNode->previousSibling, $nodeName) + $var;
}
}
//utilitaries functions off selectSingleNode
private function getFullXpath($pNode)
{
if($pNode == null)
{
return "";
}
else
{
return self::getFullXpath($pNode->parentNode) . "/" . $pNode->nodeName . "[" .strval(self::getNodePos($pNode, $pNode->nodeName)+1) . "]";//+1 to get the real xPath index
}
}
}
?>