Undefined index : notif

articles.php

<?php

function update(){
        $data['title'] = "Update Artikel";
        $data['session_user'] = $this->session_user;
        if(empty($this->uri->segment('3'))){ redirect('articles');}
        $id = $this->uri->segment('3');
        $data['articles'] = $this->articlesModel->getArticleWhere($id);
        $this->load->library('upload');

        if(count($_POST)){
        $title = str_replace(' ','-',$this->input->post('title'));
        $config['upload_path'] = './public/images/articles'; //path folder
        $config['allowed_types'] = 'jpg|png|jpeg'; //type yang dapat diakses bisa anda sesuaikan
        $config['file_name'] = $title.'_img.jpg'; //nama yang terupload nantinya
        $config['overwrite'] = true;
        $this->upload->initialize($config);
        if(!empty($_FILES['image']['name'])){
            if ($this->upload->do_upload('image'))
                {
                    $img = $this->upload->data();
                    $image = $img['file_name'];
                    $data['notif'] = $this->articlesModel->updateArticles($id,$image);
                }
        }else{
            $data['notif'] = $this->articlesModel->updateArticles($id,$this->input->post('oldImage'));
        }

        if($data['notif']['type'] == 'success'){ 
            $data['articles'] = '';
            echo '<script>setTimeout(function(){ window.location.href = "'.base_url('articles').'"; }, 1000);</script>';
        }

        }

        $this->load->view('includes/header', $data);
        $this->load->view('dashboard/article_edit', $data);
        $this->load->view('includes/footer', $data);
    }

articlesModel.php

<?php

function updateArticles($id, $image){
        $notif = array();

        $data = array(
                'title' => $this->input->post('title'),
                'tags'  => $this->input->post('tags'),
                'pic'   => $image,
                'contents' => $this->input->post('contents'),
                'is_posted'=> $this->input->post('is_posted') ? : 0
        );
        $this->db->where('article_id',$id);
        $this->db->update('articles',$data);
        if ($this->db->affected_rows() > 0) {
            $notif['message'] = 'Saved successfully';
            $notif['type'] = 'success';
            unset($_POST);
        } else {
            $notif['message'] = 'Something wrong !';
            $notif['type'] = 'danger';
        }
        return $notif;
    }