{
    $return = $this->findFirst(['fields'=>'guid', 
                 'clauses'=>"id=$id",
    ]) ; 
    
    if($return){
        return $return->getGUID();
    } 
    return $default ; 
}
 
public function findBySlug(string $slug):?Post
{
    $return = $this->findFirst([
                 'clauses'=>"slug='$slug'",
    ]) ; 
    
    if ($return===false) {
            
            throw new NotFoundException($this->table);
      
        }    
    return $return ; 
}
 
public function findByParent(int $parent):?array
{
    $return = $this->find(['fields'=>'*', 
                 'clauses'=>"parent=$parent",
    ]) ; 
    
    return $return ; 
}
 
 
//update a post 
public function update(Post $post):void
{
  $save = $this->save([
    'id'=>$post->getId(),