kohana2 auth - login problem
ORM::factory('user', $post['username'])

<?php
// grab relevant $_POST data
$username = $this->input->post('username');
$password = $this->input->post('password');

// instantiate User_Model and set attributes to the $_POST data
$user = ORM::factory('user');
$user->username = $username;
$user->password = Auth::instance()->hash_password($password);

// if the user was successfully created...
if ($user->add(ORM::factory('role', 'login')) AND $user->save()) {

    // login using the collected data
    Auth::instance()->login($username, $password);

    // redirect to somewhere
    url::redirect('user/profile');
}