Error message on callback function not show - codeigniter

Question

I have the below code:
<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');
class Login extends MY_Controller
{
function __construct()
{
parent::__construct();
$this->load->model('users/user_model');
$this->load->library('form_validation');
}
function _load_login_page()
{
$this->load->model('sysconfig/sysconfig_model');
$a = $this->sysconfig_model->get_sysconfig();
$row = $a[0];
$this->lang->load('klas',$row->sysconfig_language);
$data['sys_name'] = $row->sysconfig_system_name;
$data['template_name'] = $row->systemplate_name;
$data['css_script'] = base_url().'assets/'.$row->systemplate_name;
if($row->sysconfig_maintenance === 'Y')
{
$this->load->view('sysconfig/maintenance',$data);
}
else {
$this->load->view('login',$data);
}
}
function index()
{
$this->form_validation->set_rules('username', 'Username', 'trim|required|max_length[12]|xss_clean|callback_check_auth');
$this->form_validation->set_rules('password','Password','trim|required');
if($this->form_validation->run($this) == FALSE)
{
$this->_load_login_page();
} else {
redirect('welcome','refresh');
}
}
function check_auth()
{
if($this->user_model->authentication())
{
return TRUE;
}
$this->form_validation->set_message('check_auth',$this->lang->line('invalid_username'));
return FALSE;
}
?>
user_model.php
<?php
class User_Model extends CI_Model
{
function authentication()
{
$this->db->where('useracc_id', $this->input->post('username'));
$this->db->where('useracc_password', md5($this->input->post('password')));
$q = $this->db->get('base_useracc');
if($q->num_rows() == 1)
{
$session_data = array('isUserLogged'=>TRUE);
$this->session->set_userdata($session_data);
return TRUE;
}
}
?>
From here we can see if the user didn't fill the username and password fields, it will show the error and everything works as expected. The problem is, if the user provides an invalid username or password, the error message won't show.
for the information, I already put $lang['invalid_username'] = 'Invalid username or password'; on the language file.
I am doing this using the HMVC technique. Please help me.

Answer 1

You don't seem to be passing any data to your callback function. Callback functions expect the value of the input field to be passed as a parameter. I don't think you can make this work as a form validation callback be because the authentication method presumably needs to know both the password and the username. At present you're not passing any data into your check_auth method or indeed onwards to your user_model->authentication() method. That is why form_validation is ignoring it.
Rather than calling check_auth as a callback, why not run the form_validation first (this is really what it's for - checking the data is correct and sanitised) and then pass the values from your form to your check_auth function as part of an if statement. You will not be able to use the form_validation set_message method to display errors but I think this is a cleaner approach.
To summarise, use the form_validation to check the data you are receiving is ok and display relevant messages if it is not. Authenticating a user based on that information is a separate procedure that I don't think belongs with validation. Do you see the difference?

Answer 2

from the HMVC wiki page :
When using form validation with MX you will need to extend the CI_Form_validation class as shown below, before assigning the current controller as the $CI variable to the form_validation library. This will allow your callback methods to function properly. (This has been discussed on the CI forums also). ie:
<?php
/** application/libraries/MY_Form_validation **/
class MY_Form_validation extends CI_Form_validation
{
public $CI;
}
<?php
class Xyz extends MX_Controller
{
function __construct()
{
parent::__construct();
$this->load->library('form_validation');
$this->form_validation->CI =& $this;
}
}