正则表达式以匹配元标记

Question

Hi I want to extract the og:image content from a page source. How can I extract og:image meta tag content from source?

This is meta tag:

<meta property="og:image" content="http://www.moneycontrol.com/news_image_files/2013/s/Syrian_diesel_trucks_190.jpg" />

How can I identify the meta tag using regular expression?

This is my current function grab image url from img tags. What modification it needed to work with og:image meta tags?

function feeds_imagegrabber_scrape_images($content, $base_url, array $options = array(), &$error_log = array()) {

// Merge the default options.
$options += array(
  'expression' => '//img',
  'getsize' => TRUE,
  'max_imagesize' => 512000,
  'timeout' => 10,
  'max_redirects' => 3,
  'feeling_lucky' => 0,
);

$doc = new DOMDocument();
if (@$doc->loadXML($content) === FALSE && @$doc->loadHTML($content) === FALSE) {
  $error_log['code'] = -5;
  $error_log['error'] = "unable to parse the xml//html content";
  return FALSE;
}

$xpath = new DOMXPath($doc);
$hrefs = @$xpath->evaluate($options['expression']);//echo '<pre> HREFS : ';print_r($hrefs->length);exit;

if ($options['getsize']) {
  timer_start(__FUNCTION__);
}

$images = array();
$imagesize = 0;
for ($i = 0; $i < $hrefs->length; $i++) {
  $url = $hrefs->item($i)->getAttribute('src');
  if (!isset($url) || empty($url) || $url == '') {
    continue;
  }
  if(function_exists('encode_url')) {
    $url = encode_url($url);
  }
  $url = url_to_absolute($base_url, $url);

  if ($url == FALSE) {
    continue;
  }

  if ($options['getsize']) {
    if (($imagesize = feeds_imagegrabber_validate_download_size($url, $options['max_imagesize'], ($options['timeout'] - timer_read(__FUNCTION__) / 1000))) != -1)   {
      $images[$url] = $imagesize;
      if ($settings['feeling_lucky']) {
        break;
      }
    }
    if (($options['timeout'] - timer_read(__FUNCTION__) / 1000) <= 0) {
      $error_log['code'] = FIG_HTTP_REQUEST_TIMEOUT;
      $error_log['error'] = "timeout occured while scraping the content";
      break;
    }
  }
  else {
    $images[$url] = $imagesize;
    if ($settings['feeling_lucky']) {
      break;
    }
  }
}
echo '<pre>';print_r($images);exit;
return $images;
}

Answer 1

Make use of DOMDocument Class

<?php
$html='<meta property="og:image" content="http://www.moneycontrol.com/news_image_files/2013/s/Syrian_diesel_trucks_190.jpg" />';
$dom = new DOMDocument;
$dom->loadHTML($html);
foreach ($dom->getElementsByTagName('meta') as $tag) {
    if ($tag->getAttribute('property') === 'og:image') {
        echo $tag->getAttribute('content');
    }
}

OUTPUT :

http://www.moneycontrol.com/news_image_files/2013/s/Syrian_diesel_trucks_190.jpg