function save()
 {
     $work = new Work();
     $work->staff_id = $this->staff_id;
     $work->history_date = $this->input->post('history_date');
     $work->history_description = $this->input->post('history_description');
     if ($work->save()) {
         $this->session->set_flashdata('message', 'Work successfully created!');
         redirect('staffs/' . $this->staff_id . '/work_histories/index');
     } else {
         // Failed
         $work->error_message('custom', 'Field required');
         $msg = $work->error->custom;
         $this->session->set_flashdata('message', $msg);
         redirect('staffs/' . $this->staff_id . '/work_histories/add');
     }
 }