Undefined property,Call to a member codeigniter model function in php helper function PHP Codeigniter i -

below helper function(defined in autoload db)

<?php  function get_categories_h(){     $ci =  get_instance();     $categories = $ci->product_model->get_categories();     return $categories; } 

function in model is

public function get_categories(){      $this->db->select('*');     $this->db->from('categories');     $query = $this->db->get();     return $query->result(); } 

code in view is

<?php foreach(get_categories_h() $category) : ?>                             <li class="list-group-item"><a href="#"><?php echo $category->name; ?></a></li>                             <?php endforeach; ?> 

error getting is

message: undefined property: products::$product_model

filename: helpers/db_helper.php

fatal error: call member function get_categories() on non-object in c:\xampp\htdocs\gamingplace_done\application\helpers\db_helper.php

you need load model in helper accessible. like:

<?php  function get_categories_h(){     $ci =  get_instance();     $ci->load->model('product_model');     $categories = $ci->product_model->get_categories();     return $categories; } 

you can read more how load at: http://www.codeigniter.com/userguide2/general/models.html#loading

or

http://www.codeigniter.com/user_guide/general/models.html#loading-a-model

depending on ci version using.