by default null eloquent user data in relationship in laravel 8 code example

Example: by default null eloquent user data in relationship in laravel 8

# simple handle in blade file 
{{ $post->author->name or 'No author' }}

# Model action 
public function author()
{
    return $this->belongsTo('App\Author')->withDefault();
}

public function author()
{
    return $this->belongsTo('App\Author')->withDefault([
        'name' => 'Guest Author',
    ]);
}