Cara Update berita di swarakalibata CI

Assalamualaikum,..  maksudnya mau dihapus gambar lamanya? jika iya boleh tambahin  di 
function edit_listberita(){
   //code ...........
   if($hasil['file_name'] != ''){
        $data = array(
                    '.......' =>   '......', //dst
                );
   } else {
        $data = array(
                    '.......' =>   '......', //dst
                );
        //_______ isi codenya disini ______//
   }
   $where = '.....................';
   $this->model_app->update('berita', $data, $where);
   redirect($this->uri->segment(1).'/listberita');
}
 
 
berikut codenya:
$cekgambar = $this->model_app->view_where('berita',$where)->row_array();
if($cekgambar['gambar'] != ""){
   unlink('./asset/'.$cekgambar['gambar']);
}
 
 
jadi kurang lebih seperti dibawah ini:
function edit_listberita(){
   //code ...........
   if($hasil['file_name'] != ''){
        $data = array(
                    '.......' =>   '......', //dst
                );
   } else {
        $data = array(
                    '.......' =>   '......', //dst
                );
        $cekgambar = $this->model_app->view_where('berita',array('id_berita' => $this->input->post('id')))->row_array();
        if($cekgambar['gambar'] != ""){
             unlink('./asset/foto_berita/'.$cekgambar['gambar']);
        }
   }
   $where = '.....................';
   $this->model_app->update('berita', $data, $where);
   redirect($this->uri->segment(1).'/listberita');
}