WordPressでコメント長制限

add_filter( 'preprocess_comment', 'wpb_preprocess_comment' );
function wpb_preprocess_comment($comment) {
    if( mb_strlen( $comment['comment_content'] ) > 1000 ) {
        wp_die('Comment is too long. Please keep your comment under 1000 characters.'); 
	}
   return $comment;
}