Fungi callback pada form_validation ga berfungsi untuk konsep HMVC

	class User extends Controller
	{
		function __construct()
		{
			parent::Controller();
			$this->load->model('user/user_model');
		}
		function index()
		{
			$this->register();
		}
		function register()
		{
			$data['action_form'] = 'user/register';
			$this->form_validation->set_rules('username','Username','trim|required|alpha_numeric|min_length[6]|xss_clean|strtolower|callback_valid_username');
			$this->form_validation->set_rules('name','Name','trim|required|min_length[6]|xss_clean');
			$this->form_validation->set_rules('email','Email Address','trim|required|min_length[6]|xss_clean|valid_email');
			$this->form_validation->set_rules('password','Password','trim|required|alpha_numeric|min_length[6]|xss_clean');
			$this->form_validation->set_rules('password_conf','Password Confirmation','trim|required|alpha_numeric|min_length[6]|matches[password]|xss_clean');
			if ($this->form_validation->run() == False){
				$this->load->view('user/view_register',$data);
			}
			else
			{
				$username = $this->input->post('username');
				$name = $this->input->post('name');
				$email = $this->input->post('email');
				$password = sha1($this->input->post('password'));
				$user = array('username'=> $username, 'nama'=>$name, 'email'=> $email, 'password'=> $password);
				$this->user_model->register_user($user);
				echo 'Test';
			}
 
		}
 
		function valid_username($username)
		{
			$this->form_validation->set_message('valid_username', 'That %s already exists.');
			if($this->user_model->check_username($username))
			{
				return false;
			}
			else
			{
				return true;
			}
		}
	}

	class User_model extends Model
	{
		function __construct()
		{
			parent::Model();
		}
 
		function register_user($user)
		{
			$this->db->insert('users', $user);
		}
 
		function check_username($username)
		{
			$query = "SELECT username from users where username = ?";
			//$result = $this->db->query($query, $username);
			$result = $this->db->get_where('users',array('username'=> $username));
 
			if ($result->num_rows() > 0 )
			{
				return true;
			}
			else
			{
				return false;
			}
		}
	}

		echo form_open($action_form);
		$username 	= array('name'=>'username','id'=>'username','value'=>set_value('username'));
		$name	 	= array('name'=>'name','id'=>'name','value'=>set_value('name'));
		$email = array('name'=>'email','id'=>'email','value'=>set_value('email'));
		$password = array('name'=>'password','id'=>'password','value'=>'');
		$password_conf = array('name'=>'password_conf','id'=>'password','value'=>'');
 

		echo '<p>'. form_submit(array('name'=>'register'),'Register') . '</p>';
		echo form_close();
		echo '<p>' . validation_errors() . '</p>';