Add Post Author body class to WordPress

Question

I'm trying to add a custom body class to WordPress which should be the author of the post which is displayed. I looked at different how to's and tried to create some code but it doesn't work:

add_filter( 'body_class' , 'ft_add_guest_body_class' );

function ft_add_guest_body_class( $classes ) {

    // add 'wp_admin' to the $classes array

    if (get_the_author() != 'MrX')
        $classes[] = 'wp_admin';

    // return the $classes array
    return $classes;

}

The problem is that the wp_admin body class is displayed on every page and post. When I remove the conditional the body class is still applied so it must be that.

Answer 1

$author = $wp_query->post->post_author;
$author = get_user_by('id', $author);
author->user_nicename;

That should get you the author slug which you can use in your conditional statement. get_the_author can only be used inside the loop.

Answer 2

It's because you're trying to use get_the_author() outside of the Loop. Try using $post->post_author instead, which will return the author's ID for the current post.