wordpress 获取指定作者的所有 post meta

$args = array(
'post_type' => array( 'post','knowledgebase'),
'post_status' => 'publish',
'author' => $author_id,
'numberposts'=> $author_all_posts
);
post_title
$posts = get_posts($args);
$votes_likes_sum = ;
for ($i = ; $i < count($posts); $i++) {
$votes_likes_sum += get_post_meta($posts[$i]->ID, '_votes_likes', true);
}
echo $votes_likes_sum;
$post = $posts[];
echo $post->ID;
print get_post_meta(, '_votes_likes', true);