readfile and insert to db help

[eluser]sasori[/eluser]
I created a folder named "file" outside the system folder.

now here's my controller function

Code:

function add()
    {
        $data['words'] = $this->stock_model->putData("files/testtext.txt");
        $this->load->view('success',$data);
    }

and this is my model function to read the file

Code:

function putData($txt)
    {
      $handle = file_get_contents($txt);
      $var_array_parent = explode("\n",$handle);
      foreach($var_array_parent as $value)
      {
        $var_array = explode(";",$value);
        $a = array_chunk($var_array,4);
        for($i=0;$i<sizeof($a);$i++)
        {
          $a[$i][1] = preg_replace("/\s\%/","%",$a[$i][1]);

          $data = array(
                        'compcode' => $a[$i][0],
                        'pricepercent' => $a[$i][1],
                        'compname' => $a[$i][2],
                        'volume' => $a[$i][3]);

          $this->db->insert('stocks',$data);
        }
      }
      return $this->db->affected_rows();
    }

now am getting this error

A PHP Error was encountered

Severity: Notice

Message: Undefined property: Welcome::$stock_model

Filename: controllers/welcome.php

Line Number: 23

Fatal error: Call to a member function putData() on a non-object in C:\xampp\htdocs\myapp\system\application\controllers\welcome.php on line 23

please tell me what to do ?