Polimorphic Relation

Hello, What is the proper way of doing Polimorphyc relation between two Models where the second model is connected with two fields id and alias. When i try the below code, it produces following sql for image table:

class Property extends Model
{
    public $id;
    //conection 
    public $alias = "prop";
    public function initialize()
    {   
        $this->hasMany(array("id","alias"),"Image",array("tbl_id","tbl_name"));
    }
}

the image model:

class Image extends Model
{
    public $id;
    public $tbl_name;
    public $tbl_id;
    public $image;
}

sql:

SELECT `images`.`id`, `images`.`tbl_name`, `images`.`tbl_id`, `images`.`image` FROM `images` WHERE `images`.`tbl_id` = NULL AND `images`.`tbl_name` = NULL

As you can see the tbl_id and tbl_name are equal to NULL insted of the value of the $id and the $alias filed which is "prop" Am I doing sth wrong or ther is a bug in file: /phalcon/mvc/model/manager.zep - getRelationRecords - line 1282 shoud be

placeholders["APR" . refPosition] = record->readAttribute(fields[refPosition])