PHP使用PHPDocumente（）获得html标记值

Question

这是简单的html代码，我想从中得到sorry ， promise和back-link值

<div id="core">
  <h1 id="sorry">Sorry, something went wrong.</h1>
  <p id="promise">
    We're working on it and we'll get it fixed as soon as we can.
  </p>
  <p id="back-link">
    <a id="back" href="https://www.facebook.com/">Go Back</a>
  </p>
  <div id="footer">
    Facebook
    <span id="copyright">
      © 2018
    </span>
    <span id="help-link">
      ·
      <a id="help" href="https://www.facebook.com/help/">Help Center</a>
    </span>
  </div>
</div>

用下面的代码我得到其中之一的结果，例如：

DOMElement Object
(
    [tagName] => p
    [schemaTypeInfo] => 
    [nodeName] => p
    [nodeValue] => 
        Go Back

    [nodeType] => 1
    [parentNode] => (object value omitted)
    [childNodes] => (object value omitted)
    [firstChild] => (object value omitted)
    [lastChild] => (object value omitted)
    [previousSibling] => (object value omitted)
    [nextSibling] => (object value omitted)
    [attributes] => (object value omitted)
    [ownerDocument] => (object value omitted)
    [namespaceURI] => 
    [prefix] => 
    [localName] => p
    [baseURI] => 
    [textContent] => 
        Go Back

)

但它是所有属性的唯一对象，而不是我想要的东西，我想从此html获取sorry ， promise和back-link值

我的代码：

<?php
$url = "http://localhost/error.html";
$html = file_get_contents($url);
$doc = new DOMDocument(); // create DOMDocument
libxml_use_internal_errors(true);

$doc->loadHTML($html); // load HTML you can add $html
//libxml_clear_errors();

if ($html) {
    $divs = $doc->getElementById('core');

    $xpath = new DOMXPath($doc);

    $backLink = $xpath->query('//p[@id="back-link"]');

    //$sorryId = $xpath->query('//h1[@id="sorry"]');
    //$promiseId = $xpath->query('//p[@id="promise"]');


    $node = $backLink->item(0);
    $href = $node->getAttribute('href');
    echo '<pre>';print_r($node);echo '</pre>';
}
?>

请帮助我修复此代码以从html获取值，在此先感谢

Answer 1

由于id在html页面上必须唯一，因此可以使用简单的getElementById ：

if ($html) {
    $sorry = $doc->getElementById('sorry');
    var_dump($sorry->textContent);

    $promise = $doc->getElementById('promise');
    var_dump($promise->textContent);

    // here I use `back` id as you need link 
    // from this element, not from `back-link`
    $backLink = $doc->getElementById('back')->getAttribute('href');
    var_dump($backLink);
}