如何在WordPress中调用缩略图从图像uSignTypes插件

Question

我使用Wordpress中的Types插件创建自定义帖子类型。我已经添加了自定义字段“图像字段”，这是一个重复字段，通过这种方式，我想在我的帖子类型中创建类似gallery的内容

我是这样称呼前端的图像的

       $images = get_post_meta(get_the_ID(), 'wpcf-application-image');          
       foreach ($images as $image) {

        echo '<a rel="attachment" href="' . $image . '"><img src="' . $image . '" /></a>'; 

        } 

使用该代码，我可以看到包含所有图像和媒体文件链接的列表。但是我如何在img标签中添加缩略图而不是精确的图像呢？非常感谢。

Answer 1

你好，西蒙，谢谢你的帮助！我添加了你发布的代码，但是图像没有显示，我有

 <img src="Array"> 

但是你展示了正确的方式，我修改了我的代码，现在它的工作！这是我所拥有的：

function get_attachment_id_from_src ($image_src) {
            global $wpdb;
            $query = "SELECT ID FROM {$wpdb->posts} WHERE guid='$image_src'";
            $id = $wpdb->get_var($query);
            return $id;
        }

        $images = get_post_meta(get_the_ID(), 'wpcf-application-image');          
        foreach ($images as $image) {
          $image_src = get_attachment_id_from_src($image);                
          $image_thumb = wp_get_attachment_image ($image_src, 'medium');

          echo '<a rel="attachment" href="' . $image . '">'. $image_thumb .'</a>'; 
        }

再次感谢！

Answer 2

如果您只有图像url（而不是id），则可以使用如下函数返回url（将其添加到functions.php等）：

/**
 * Return an ID of an attachment by searching the database with the file URL.
 *
 * First checks to see if the $url is pointing to a file that exists in
 * the wp-content directory. If so, then we search the database for a
 * partial match consisting of the remaining path AFTER the wp-content
 * directory. Finally, if a match is found the attachment ID will be
 * returned.
 *
 * @param string $url The URL of the image (ex: http://example.com/wp-content/uploads/2013/05/test-image.jpg)
 *
 * @return int|null $attachment Returns an attachment ID, or null if no attachment is found
 */
function get_attachment_id_by_url( $url ) {
  // Split the $url into two parts with the wp-content directory as the separator
  $parsed_url  = explode( parse_url( WP_CONTENT_URL, PHP_URL_PATH ), $url );
  // Get the host of the current site and the host of the $url, ignoring www
  $this_host = str_ireplace( 'www.', '', parse_url( home_url(), PHP_URL_HOST ) );
  $file_host = str_ireplace( 'www.', '', parse_url( $url, PHP_URL_HOST ) );
  // Return nothing if there aren't any $url parts or if the current host and $url host do not match
  if ( ! isset( $parsed_url[1] ) || empty( $parsed_url[1] ) || ( $this_host != $file_host ) ) {
    return;
  }
  // Now we're going to quickly search the DB for any attachment GUID with a partial path match
  // Example: /uploads/2013/05/test-image.jpg
  global $wpdb;
  $attachment = $wpdb->get_col( $wpdb->prepare( "SELECT ID FROM {$wpdb->prefix}posts WHERE guid RLIKE %s;", $parsed_url[1] ) );
  // Returns null if no attachment is found
  if(isset($attachment[0])) {
    return $attachment[0];
  } else {
    return null;
  }
}

然后您可以使用该ID来显示缩略图：

$images = get_post_meta(get_the_ID(), 'wpcf-application-image');          
foreach ($images as $image) {
  $image_id = get_attachment_id_by_url($image);
  echo '<a rel="attachment" href="' . $image . '"><img src="' . wp_get_attachment_image_src($image_id,'thumbnail') . '" /></a>'; 
}