I have two controller functions both need one model function but when I pass parameters to single model function it shows me an error, I need help if there is another method to pass parameters

Controller

```
public function view_files()
{
    $assignment_id='1255';
    $data['files'] = $this->AdminModel->getRows111();
    $this->load->view('admin/view_files', $data);
}

function download_test1(){
    $id = $this->uri->segment(3);

    if (empty($id)){
           redirect(base_url());
    }

    $data = $this->AdminModel->getRows111($id);
    $filename =$data['assignment_file_name'];
    $fileContents = file_get_contents(base_url('upload/'. 
         $data['assignment_file_name'])); 

    force_download($filename, $fileContents);

}

```

**Model**

```
public function getRows111($id=''){
    $this->db->select('*');
    $this->db->where('assignment_id','1255');
    $this->db->from('tbl_assignments_files');

    if($id){
        $this->db->where('assignment_file_id',$id);
        $query = $this->db->get();
        $result = $query->row_array();

    }else{
       $query = $this->db->get();
       $result = $query->result_array();

    }

    return !empty($result)?$result:false;

   }
}

```

function 1

```
$data['files'] = $this->AdminModel->getRows111(assignment_id);

```

function 2

```
$data = $this->AdminModel->getRows111($id);

```

model *by doing this, shows error*

```
public function getRows111($id='',$assignment_id){

```