DomXPath：在DomXPath查询结果中搜索吗？

Question

How can I query an xpath result for a sub element, without querying the entire document again? 如何查询子元素的xpath结果，而无需再次查询整个文档？

I query my document to find the last <li> with the class menu-item : 我查询我的文档以找到最后一个<li>类class menu-item ：

$doc = new DomDocument();
@$doc->loadHTML( $html );
// $html is invalid (and should be at this point),
// so use @ sign to suppress errors
$xpath = new DomXPath( $doc );
$li = $xpath->query( "(//li[contains(concat(' ', normalize-space(@class), ' '), 'menu-item')])[last()]" )->item( 0 );

The above works just fine, now I want to query $li to find the following: 上面的工作很好，现在我要查询$li以查找以下内容：

$p = $xpath->query( "//p[contains(concat(' ', normalize-space(@class), ' '), 'field-description')]" )->item( 0 );

A p tag with class field-description . 具有类field-description p标签。 This does not work and returns the first instance found, if I modify it and use the [last()] (whatever this is) then it works, but it's not necessarily the optimal solution here: 这不起作用并返回找到的第一个实例，如果我对其进行修改并使用[last()] （无论这是什么），则它可以工作，但不一定是这里的最佳解决方案：

$p = $xpath->query( "(//p[contains(concat(' ', normalize-space(@class), ' '), 'field-description')])[last()]" )->item( 0 );

The above line works, but I want to query inside $li not the entire document again. 上面的行有效，但是我想在$li内部而不是整个文档中再次查询。

Answer 1

The second argument to query is the contextnode , which limits the search to within that node. query 的第二个参数是contextnode ，它将搜索限制在该节点内。 However, if you use an absolute xpath, query will still return nodes for the entire document. 但是，如果使用绝对xpath， query仍将返回整个文档的节点。

php > $dd = new DomDocument();
php > // deliberately using malformed html.
php > $dd->loadhtml('<html><head><title>wat</title></head><body><div>Hello, <p>world</p></div><div class="container"><p>I like pie</div></body></html>');
php > $xp = new DomXPath($dd); 
php > $container = $xp->query('//div[@class="container"]')->item(0);
php > var_dump($xp->query('//p'));
class DOMNodeList#6 (1) {
  public $length =>
  int(2)
}
php > var_dump($xp->query('//p', $container));
class DOMNodeList#4 (1) {
  public $length =>
  int(2)
}
php > var_dump($xp->query('p', $container));
class DOMNodeList#5 (1) {
  public $length =>
  int(1)
}

You can use a pattern like .//x to match all x elements recursively within a context node. 您可以使用.//x类的模式来在上下文节点中递归匹配所有x元素。 (HT: Alf Eaton ) （HT：阿尔夫·伊顿）

DomXPath：在DomXPath查询结果中搜索吗？

问题描述

1 个解决方案

解决方案1
3 2014-04-12 00:48:05

DomXPath：在DomXPath查询结果中搜索吗？

问题描述

1 个解决方案

解决方案1 3 2014-04-12 00:48:05

解决方案1
3 2014-04-12 00:48:05