MY Model Joins

[eluser]xtremer360[/eluser]
I am attempting to find out how to understand the use of Jamie Rumbelow's MY_Model in specific of how to implement this idea.

I'm putting a game app together. There are many users and many characters. Each user can have many characters but only each character can be controlled by one user. I have a user's table that has a field called default_character. This is the foreign key that is represented by the id field of the character.

In my code I am using the following function call to get the current logged in user.

Code:

$user_data = $this->user->get_by('username', $post_username);

What I would like to do is when I do this and it adds in the integer value from the default_character field instead I would like for it to go get the name of that character. What would this look like?

Code:

tables

user - user_id, username, default_character_id

characters - id, character_name

object(stdClass)#23 (12) {
    ["user_id"]=>
    string(5) "10003"
    ["first_name"]=>
    string(3) "tom"
    ["last_name"]=>
    string(8) "williams"
    ["username"]=>
    string(9) "twilliams"
    ["password"]=>
    string(40) "431db25cf8fe0ccf374365ae9c644c7bfdeb7399"
    ["password_hash"]=>
    string(11) "ed95d918116"
    ["email_address"]=>
    string(19) "[email protected]"
    ["status_id"]=>
    string(1) "2"
    ["lock_date"]=>
    string(19) "0000-00-00 00:00:00"
    ["default_character_id"]=>
    string(1) "1"
    ["created_at"]=>
    string(19) "2013-07-30 10:00:00"
    ["updated_at"]=>
    string(19) "0000-00-00 00:00:00"
}

User Model(application/modules/user/models/user_model.php) (Loaded in MY_Controller)

Code:

<?php

class User_model extends MY_Model
{    
    public $primary_key = 'user_id';
    public $has_many = array('characters' => array('model' => 'character_model' ));

    public function __construct()
    {
        parent::__construct();
    }
}

Character Model(application/modules/character/models/character_model.php)(Loaded in control panel controller)

Code:

<?php

class Character_model extends MY_Model
{    
    public $belongs_to = array('user' => array('primary_key' => 'default_character_id'));

    public function __construct()
    {
        parent::__construct();
    }
}

I'm wondering if this is a database structure issue. Any more thoughts on this topic? Any help would be great.

I'm still having some concerns on what I'm doing wrong. Anybody able to help me out?