使用PHP DOM文档,按类选择HTML元素并获取其文本

Question

我试图通过使用PHP的DOM元素和下面的HTML(相同的结构)和下面的代码来从div中获取文本,其中class = 'review-text'.

然而,这似乎不起作用

1. HTML

   $html = '
       <div class="page-wrapper">
           <section class="page single-review" itemtype="http://schema.org/Review" itemscope="" itemprop="review">
               <article class="review clearfix">
                   <div class="review-content">
                       <div class="review-text" itemprop="reviewBody">
                       Outstanding ... 
                       </div>
                   </div>
               </article>
           </section>
       </div>
   ';
   

2. PHP代码

       $classname = 'review-text';
       $dom = new DOMDocument;
       $dom->loadHTML($html);
       $xpath     = new DOMXPath($dom);
       $results = $xpath->query("//*[@class and contains(concat(' ', normalize-space(@class), ' '), ' $classname ')]");
   
       if ($results->length > 0) {
           echo $review = $results->item(0)->nodeValue;
       }
   

此博客提供了按类选择元素的XPATH语法

我在StackOverflow,在线教程中尝试过很多例子,但似乎都没有.我错过了什么吗？

Answer 1

以下XPath查询执行您想要的操作.只需用以下代码替换提供给$ xpath-> query的参数:

//div[@class="review-text"]

编辑:为了便于开发,您可以在http://www.xpathtester.com/test上在线测试自己的XPath查询.

Edit2:测试了这段代码; 它工作得很好.

<?php

$html = '
    <div class="page-wrapper">
        <section class="page single-review" itemtype="http://schema.org/Review" itemscope="" itemprop="review">
            <article class="review clearfix">
                <div class="review-content">
                    <div class="review-text" itemprop="reviewBody">
                    Outstanding ... 
                    </div>
                </div>
            </article>
        </section>
    </div>
';

$classname = 'review-text';
$dom = new DOMDocument;
$dom->loadHTML($html);
$xpath = new DOMXPath($dom);
$results = $xpath->query("//*[@class='" . $classname . "']");

if ($results->length > 0) {
    echo $review = $results->item(0)->nodeValue;
}

?>

Answer 2

扩展Frak Houweling 的答案，还可以使用DomXpath在特定的DomNode 中进行搜索。这可以通过将 传递contextNode给DomXpath->query方法的第二个参数来实现：

$dom = new DOMDocument;
$dom->loadHTML ($html);
$xpath = new DOMXPath ($dom);

foreach ($xpath->query ("//section[@class='page single-review']") as $section)
{
    // search for sub nodes inside each element
    foreach ($xpath->query (".//div[@class='review-text']", $section) as $review)
    {
        echo $review->nodeValue;
    }
}

请注意，在节点内部搜索时，您需要通过.在表达式开头添加一个点来使用相对路径：

"//div[@class='review-text']" // absolute path, search starts from the root element
".//div[@class='review-text']" // relative path, search starts from the provided contextNode