PHP php-activerecord code for checking existence and reusing before creating

check_existance

//validations
static $validates_presence_of = array( //TODO

//alterations
static $before_create = array('check_existence');

function check_existence()
{
  $find_by = array();
  foreach(self::$validates_presence_of as $key)
  {
    $key = $key[0];
    $find_by[$key] = $this->$key;
  }
  $result = self::first($find_by);
  if ($result != null)
  {
    $this->set_attributes($result->attributes());
    return false;
  }
  return true;
}