$this trouble

[eluser]Unknown[/eluser]
Hello,
could you tell me, what is the problem with my model?

There is a table: id, parent, messages. And I want to create an array tree. Something like this:

Code:

Array
(
    [1] => stdClass Object
        (
            [id] => 1
            [parent] => 0
            [message] => This is 1. message
            [children] => Array
                (
                    [2] => stdClass Object
                        (
                            [id] => 2
                            [parent] => 1
                            [message] => This is 2. message
                            [children] =>
                        )

                )

        )

)

so, here is my model:

Code:

class Messages_model extends CI_Model {

    private $messageArray = array();

    function get_all_messages($parent = 0)
    {
        $query = $this->db->where('parent', $id)->get('messages');

        if ($query->num_rows() > 0) {
            foreach ($query->result() as $message)
            {
                $this->messageArray[$message->id] = $messages;
                $this->messageArray[$message->id]->children = $this->get_all_messages($message->id);
            }
        }

        if (!empty($this->$messageArray)) return $this->messageArray; else return NULL;
    }
}

Now there is *RECURSION*, and without ($this->) before all messageArray (just $messageArray) it works fine, and I dont know why. :/
Thanks for any help