[WordPress][PHP] Google Search API で関連記事を取得するサンプル

gsearch_test.php

<?php
include('/path/to/wordpress/wp-load.php');

$post_id_org = 2895;  // post ID

// get keywords
$keywords = array();
$tags_categories = get_the_terms($post_id_org, array('post_tag','category'));
foreach ($tags_categories as $val) {
  if ( in_array($val->name, $keywords) )
    continue;
  $keywords[] = $val->name;
}
unset($tags_categories);

// get related posts
$related_posts = get_related_posts($keywords, 0, 8);
foreach ( $related_posts as $post_id => $post ) {
  if ( $post_id === $post_id_org )
    continue;
  $permalink = get_permalink($post_id);
  echo "{$post_id} : {$post->post_title} {$permalink}\n";
}

// get related posts from Google Search API
function get_related_posts($keywords, $start = 0, $max = 8) {
  $related_posts = array();

  $site = trailingslashit(get_home_url());
  $gs_url = 'https://ajax.googleapis.com/ajax/services/search/web?v=1.0&q=%1$s&rsz=%2$d&start=%3$d';
  $gs_query = sprintf('site:%1$s ("%2$s")', $site, implode('" OR "', $keywords));
  $response = wp_remote_get(sprintf($gs_url, urlencode($gs_query), $max, $start));
  if ( !is_wp_error($response) && $response['response']['code'] == 200) {
    $results = json_decode($response['body'])->responseData->results;
    foreach ($results as $result) {
      $post_id = intval(url_to_postid($result->url));
      if ( !$post_id )
        continue;
      $related_posts[$post_id] = get_post($post_id);
    }
  }
  unset($response);

  return $related_posts;
}