Maintenance::_migrate PHP Method

    private function _migrate()
    {
        $this->user->restrict('Admin.Maintenance.Manage');
        if ($this->input->post('migrate') and is_numeric($this->input->post('migrate'))) {
            if (ENVIRONMENT === 'production' and $this->config->item('maintenance_mode') !== '1') {
                $this->alert->set('warning', sprintf($this->lang->line('alert_warning_maintenance'), 'migrate'));
            } else {
                $this->load->library('migration');
                $migrate = (int) $this->migration->get_migration_number($this->input->post('migrate'));
                if ($this->migration->version($migrate, 'core')) {
                    $this->alert->set('success', sprintf($this->lang->line('alert_success'), 'Database migrated '));
                } else {
                    $this->alert->set('warning', sprintf($this->lang->line('alert_error'), $this->migration->error_string()));
                }
            }
        }
        return TRUE;
    }