PHP 7.0.6 Released

    DOMXPath::evaluate

    (PHP 5 >= 5.1.0, PHP 7)

    DOMXPath::evaluate — Evaluates the given XPath expression and returns a typed result if possible

    Description

    public mixed DOMXPath::evaluate ( string $expression [, DOMNode $contextnode [, bool $registerNodeNS = true ]] )

    Executes the given XPath expression and returns a typed result if possible.

    Parameters

    expression

    The XPath expression to execute.

    contextnode

    The optional contextnode can be specified for doing relative XPath queries. By default, the queries are relative to the root element.

    registerNodeNS

    The optional registerNodeNS can be specified to disable automatic registration of the context node.

    Return Values

    Returns a typed result if possible or a DOMNodeList containing all nodes matching the given XPath expression.

    If the expression is malformed or the contextnode is invalid, DOMXPath::evaluate() returns FALSE.

    Changelog

    Version Description
    5.3.3 The registerNodeNS parameter was added.

    Examples

    Example #1 Getting the count of all the english books

    <?php

    $doc     = new DOMDocument;

    $doc->load('book.xml');

    $xpath = new DOMXPath($doc);

    $tbody = $doc->getElementsByTagName('tbody')->item(0);

    // our query is relative to the tbody node
    $query = 'count(row/entry[. = "en"])';

    $entries = $xpath->evaluate($query, $tbody);
    echo     "There are $entries english books\n";

    ?>

    The above example will output:

    There are 2 english books

    See Also

    User Contributed Notes

    yuriucsal at NOSPAM dot yahoo dot com dot br
    11 years ago
    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

                    }
            }
        }
    ?>
    Damien Bezborodov
    5 years ago
    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 at danielnorton dot com
    4 years ago
    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.
    aazaharov81 at gmail dot com
    1 year ago
    To query DOMNodes by their HTML classes, use such snippet
    <?php

    // CssClassXPathSelector
    function ccxs($class) {
        return     '[contains(concat(" ", normalize-space(@class), " "), " ' . $class . ' ")]';
    }

    // then just
    $domitems = $this->xpath("//*[@id='searchResultsRows']//a" . ccxs('listing_row'));
    ?>
    daniel ad demus dk
    7 years ago
    It seems this method is only included from PHP 5.1.
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