public function generate_delivery_data_post()
 {
     $file_path = $this->input->post('filePath');
     // e:\sample_path.json
     $delivery_id = $this->input->post('deliveryId');
     $deliveries_repo = new Deliveries_Repository($this->base_model->get_db_instance());
     $delivery_data = $deliveries_repo->to_delivery_json($delivery_id);
     $enc = new Encryption();
     $file_size = file_put_contents($file_path, $enc->encrypt($delivery_data));
     if ($file_size >= 1) {
         $deliveries_repo->update_delivery_status($delivery_id, Delivery_Status::Success);
     } else {
         $deliveries_repo->update_delivery_status($delivery_id, Delivery_Status::Failed);
     }
     echo $file_size;
     // if >= 1, write is successful
 }