如何在DOMNode上执行XPath查询？ [英] How do I do an XPath query on a DOMNode?

查看：113 发布时间：2017/6/25 2:04:56 php dom

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问题描述

有没有办法在DOMNode上执行xpath查询？或至少将其转换为DOMXPath？

 < html> 
 ... 
< div id =content> 
 ... 
< div class =listing> 
 ... 
< div>< / div> 
< div>< / div> 
< div class ='foo'> 
< h3>获取1< / h3> 
< a>和我也1< / a> 
< / div> 
< / div> 
< div class =listing> 
 ... 
< div>< / div> 
< div>< / div> 
< div class ='foo'> 
< h3> Get me 2< / h3> 
< a>和我也1< / a> 
< / div> 
< / div> 
 .... 
< / div> 
< / html>

这是我的代码。我正在尝试获取一个数组的列表，其中包含h3的值和每个数组中的一个标签。为此，我需要获得每个列表，然后在每个列表中获取h3和标签的价值。

  $ html_dom = new DOMDocument（）; 
 @ $ html_dom-> loadHTML（$ html）; 
 $ x_path = new DOMXPath（$ html_dom）; 
 
 $ nodes = $ x_path-> query（// div [@ id ='content'] // div [@ class ='listing']）; 
 
 foreach（$ nodes as $ node）
 {
 //我想进一步挖掘这里使用DOMNode上的查询
}

解决方案

将节点作为第二个参数传递给 DOMXPath :: query

contextnode ：可以指定可选的contextnode进行相对的XPath查询。默认情况下，查询与根元素相关。

示例：

  foreach（$ nodes as $ node）{
 foreach（$ x_path-> query（'h3 | a'，$ node）as $ child）{
 echo $ child-> nodeValue，PHP_EOL; 
} 
}

这使用 UNION运算符的结果

得到我1 
和我也1 
让我2 
和我也1

如果您不需要任何复杂的查询，您还可以执行

  foreach （$ nodes as $ node）{
 foreach（$ node-> getElementsByTagName（'a'）as $ a）{
 echo $ a-> nodeValue，PHP_EOL; 
} 
}

甚至通过迭代子节点（注意这个包括所有文本节点）

  foreach（$ nodes as $ node）{
 foreach（$ node-> childNodes为$ child）{
 echo $ child-> nodeName，PHP_EOL; 
} 
}

然而，所有这些都是不必要的，因为你可以获取这些节点直接：

  $ nodes = $ x_path-> query（/ html / body // div [@ class = '列出'] /格[最后（）]）; 
 
 foreach（$ nodes as $ i => $ node）{
 echo $ i，$ node-> nodeValue，PHP_EOL; 
}

将给你所有div的最后一个div子节点的两个节点，列出并输出组合的文本节点值的类属性值，包括空格

  0 
获取1 
和我也1 
 
 1 
让我2 
和我也1

同样，以下

 // div [@ class ='listing'] / div [last（）] / node（）[name（）='h3'或name（）='a']

将给你四个孩子H3和A节点并输出

  0获取1 
 1and我也是1 
 2Get我2 
 3和我也1

如果你需要通过名称来区分这些名称，您可以执行

  foreach（$ nodes as $ i => $ node） {
 echo $ i，$ node-> nodeName，$ node-> nodeValue，PHP_EOL; 
}

然后会给

  0h3获取1 
 1aand我也是1 
 2h3收获我2 
 3a和我也1 
  / pre> 
Is there a way to do an xpath query on a DOMNode? Or at least convert it to a DOMXPath?
<html>
  ...
  <div id="content">
     ...
     <div class="listing">
         ...
         <div></div>
         <div></div>
         <div  class='foo'>
           <h3>Get me 1</h3>
           <a>and me too 1</a>
         </div>
     </div>
     <div class="listing">
         ...
         <div></div>
         <div></div>
         <div class='foo'>
           <h3>Get me 2</h3>
           <a>and me too 1</a>
         </div>
     </div>
     ....
  </div>
</html>
This is my code. I am trying to get a list of array that has the values of the h3 and a tags in each array. To do that, I needed to get each listing, and then get the h3 and a tag's value in each listing.
$html_dom = new DOMDocument();
@$html_dom->loadHTML($html);
$x_path = new DOMXPath($html_dom);

$nodes= $x_path->query("//div[@id='content']//div[@class='listing']");

foreach ($nodes as $node)
{
  // I want to further dig down here using query on a DOMNode
}

 解决方案 
Pass the node as the second argument to DOMXPath::query

  contextnode: The optional contextnode can be specified for doing relative XPath queries. By default, the queries are relative to the root element.
Example:
foreach ($nodes as $node) {
    foreach ($x_path->query('h3|a', $node) as $child) {
        echo $child->nodeValue, PHP_EOL;
    }
}
This uses the UNION operator for a result of
Get me 1
and me too 1
Get me 2
and me too 1
If you don't need any complex querying, you can also do
foreach ($nodes as $node) {
    foreach ($node->getElementsByTagName('a') as $a) {
      echo $a->nodeValue, PHP_EOL;
    }
}
Or even by iterating the child nodes (note that this includes all the text nodes)
foreach ($nodes as $node) {
    foreach ($node->childNodes as $child) {
      echo $child->nodeName, PHP_EOL;
    }
}
However, all of that is unneeded since you can fetch these nodes directly:
$nodes= $x_path->query("/html/body//div[@class='listing']/div[last()]");

foreach ($nodes as $i => $node) {
    echo $i, $node->nodeValue, PHP_EOL;
}
will give you two nodes in the last div child of all the divs with a class attribute value of listing and output the combined text node values, including whitespace
0
           Get me 1
           and me too 1

1
           Get me 2
           and me too 1
Likewise, the following
"//div[@class='listing']/div[last()]/node()[name() = 'h3' or name() = 'a']"
will give you the four child H3 and A nodes and output
0Get me 1
1and me too 1
2Get me 2
3and me too 1
If you need to differentiate these by name while iterating over them, you can do
foreach ($nodes as $i => $node) {
    echo $i, $node->nodeName, $node->nodeValue, PHP_EOL;
}
which will then give
0h3Get me 1
1aand me too 1
2h3Get me 2
3aand me too 1


                        
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如何在DOMNode上执行XPath查询？ [英] How do I do an XPath query on a DOMNode?

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