DOMXPath::query

    (PHP 5, PHP 7, PHP 8)

    DOMXPath::query — Evaluates the given XPath expression

    说明

    publicDOMXPath::query(string$expression, ?DOMNode$contextNode = null, bool$registerNodeNS = true): mixed

    Executes the given XPath expression.

    参数

    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

    Whether to automatically register the in-scope namespace prefixes of the context node to the DOMXPath object. This can be used to avoid needing to call DOMXPath::registerNamespace() manually for each in-scope namespaces. When a namespace prefix conflict exists, only the nearest descendant namespace prefix is registered.

    返回值

    Returns a DOMNodeList containing all nodes matching the given XPath expression. Any expression which does not return nodes will return an empty DOMNodeList.

    If the expression is malformed or the contextNode is invalid, DOMXPath::query() returns false.

    示例

    示例 #1 Getting all the english books

    <?php

    $doc     = new DOMDocument;

    // We don't want to bother with white spaces
    $doc->preserveWhiteSpace = false;

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

    $xpath = new DOMXPath($doc);

    // We start from the root element
    $query = '//book/chapter/para/informaltable/tgroup/tbody/row/entry[. = "en"]';

    $entries = $xpath->query($query);

    foreach (    $entries as $entry) {
    echo     "Found {$entry->previousSibling->previousSibling->nodeValue}," .
    " by {$entry->previousSibling->nodeValue}\n";
    }
    ?>

    以上示例会输出：

    Found The Grapes of Wrath, by John Steinbeck Found The Pearl, by John Steinbeck

    We can also use the contextNode parameter to shorten our expression:

    <?php

    $doc     = new DOMDocument;
    $doc->preserveWhiteSpace = false;

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

    $xpath = new DOMXPath($doc);

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

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

    $entries = $xpath->query($query, $tbody);

    foreach (    $entries as $entry) {
    echo     "Found {$entry->previousSibling->previousSibling->nodeValue}," .
    " by {$entry->previousSibling->nodeValue}\n";
    }
    ?>

    参见

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