function __construct($params = null)
{
parent::__construct($params);
if (!$this->parent_column) {
$this->parent_column = "parent";
}
if (!$this->children_column) {
$this->children_column = "children";
}
$this->define($this->parent_column, "ForeignKey", array("col_name" => $this->parent_column . "_" . $this->primary_key, "target_model" => get_class($this)));
$this->define($this->children_column, "HasManyField", array("target_model" => get_class($this), "join_field" => $this->parent_column . "_" . $this->primary_key, "eager_loading" => true));
}
