每个人我一直在制作一个wordpress插件，它可以获取不同的instagram照片，然后将它们放入短代码中。尽管如此，这些短代码显示的图像并不是保存在WP images文件夹中，而是直接从instagram中获取的。这使得服务器加载时间大幅增加。

所以我搜索了WP dev论坛，找到了这个为指定帖子设置特色图片的函数。

function Generate_Featured_Image( $image_url, $post_id  ){
    $upload_dir = wp_upload_dir();
    $image_data = file_get_contents($image_url);
    $filename = basename($image_url);
    if(wp_mkdir_p($upload_dir[\'path\']))     $file = $upload_dir[\'path\'] . \'/\' . $filename;
    else                                    $file = $upload_dir[\'basedir\'] . \'/\' . $filename;
    file_put_contents($file, $image_data);

    $wp_filetype = wp_check_filetype($filename, null );
    $attachment = array(
        \'post_mime_type\' => $wp_filetype[\'type\'],
        \'post_title\' => sanitize_file_name($filename),
        \'post_content\' => \'\',
        \'post_status\' => \'inherit\'
    );
    $attach_id = wp_insert_attachment( $attachment, $file, $post_id );
    require_once(ABSPATH . \'wp-admin/includes/image.php\');
    $attach_data = wp_generate_attachment_metadata( $attach_id, $file );
    $res1= wp_update_attachment_metadata( $attach_id, $attach_data );
    $res2= set_post_thumbnail( $post_id, $attach_id );
}

我所缺少的是，我拍摄的照片很快就会更新，而特色图片在此之后不会改变。有没有办法在新instagram照片上传后立即更新特色图片？或者每小时左右。非常感谢，伙计们！

if( wp_mkdir_p( $upload_dir[ \'path\' ] ) ) {
    $file = $upload_dir[ \'path\' ] . \'/\' . $filename;
} else {
    $file = $upload_dir[ \'basedir\' ] . \'/\' . $filename;
}

$attach_id = media_sideload_image( $image_url, $post_id, \'Instagram image\', \'id\' );
set_post_thumbnail( $post_id, $attach_id );