set_post_thumbnail( int|WP_Post $post, int $thumbnail_id ): int|bool

使用示例

• 示例1

  要以编程方式将上载的图片文件设置为缩略图，可以使用以下代码…

  /*
   * $file is the path to your uploaded file (for example as set in the $_FILE posted file array)
   * $filename is the name of the file
   * first we need to upload the file into the wp upload folder.
   */
  $upload_file = wp_upload_bits( $filename, null, @file_get_contents( $file ) );
  i
  f ( ! $upload_file['error'] ) {
    // if succesfull insert the new file into the media library (create a new attachment post type).
    $wp_filetype = wp_check_filetype($filename, null );
  
    $attachment = array(
      'post_mime_type' => $wp_filetype['type'],
  	'post_parent'    => $post_id,
  	'post_title'     => preg_replace( '/\.[^.]+$/', '', $filename ),
  	'post_content'   => '',
  	'post_status'    => 'inherit'
    );
  
    $attachment_id = wp_insert_attachment( $attachment, $upload_file['file'], $post_id );
  
    if ( ! is_wp_error( $attachment_id ) ) {
       // if attachment post was successfully created, insert it as a thumbnail to the post $post_id.
       require_once(ABSPATH . "wp-admin" . '/includes/image.php');
  
       $attachment_data = wp_generate_attachment_metadata( $attachment_id, $upload_file['file'] );
  
       wp_update_attachment_metadata( $attachment_id,  $attachment_data );
       set_post_thumbnail( $post_id, $attachment_id );
     }
  }

• 示例2

  返回值不是：“成功时为true”

  成功时，返回值是update_post_meta函数返回的新meta字段ID，如果delete_post_meta成功，则返回值为TRUE。

• 示例3

  此方法将在第二次运行时返回false。如果特色图像已设置为您提供的附件ID，则该方法将返回false，因为`update_post_meta`在值不会更改时返回false。