Laravel Api Resource User name get only

Question

public function toArray($request)
    {
        return [
            'id' => $this->id,
            'created_by_id' => $this->created_by_id ? $this->created_by_id : 'N/A',
            'updated_by_id' => $this->updated_by_id ? $this->updated_by_id : 'N/A',
            'blog_category_id' => $this->blog_category_id ? $this->blog_category_id : 'N/A',
            'title' => $this->title,
            'status' => $this->status,
            'image' => $this->image,
            'desc' => $this->desc,
        ];
    }

this is my api resource here i want to get the user name in created and updated part . what will be efficient way to get the name only.