how to ganarate input array in Codeigniter

i have code like this in controller :

            $date =  $this->input->post('date');
            $exca_id =  $this->input->post('exca_id');
            $status =  $this->input->post('id_status');

            $data = array(
                    'date' => $date,
                    'exca_id' => $exca_id,
                    'fleet_status' => $fleet,
                    'id_status' => $status,
                );

            if ((in_array("id_status", $data)) !== working ) {
               $fleet = date('ymd',strtotime(str_replace('-', '/', $date))).$shift.$status;
            }
            else
            {
                $fleet = date('ymd',strtotime(str_replace('-', '/', $date))).$shift.$exca_id;
            }

i want to save fleet_status when someone input in form input id_status == working, fleet_status save with format ganarate "date('ymd',strtotime(str_replace('-', '/', $date))).$exca_id;" but when someone input in form input id_status !== working, fleet_status save with format ganarate "$fleet = date('ymd',strtotime(str_replace('-', '/', $date))).$status;"

But, when i try this code fleet_status not save anything.

can you help me to solve this probelm?