$firstTime=strtotime($model->in_time);
                    $lastTime=strtotime($model->out_time);
                    $timeDiff=ceil(($lastTime-$firstTime)/60);

                    if($timeDiff <=30)
                        $model->price_charged = 4;
                    elseif($timeDiff >30 && $timeDiff <=60)
                        $model->price_charged = 6;
                    else{

                    }

                    throw new CException ( $model->out_time.'-'.$model->in_time.'='.$timeDiff.' Amount '.$model->price_charged);