public function get_all()
 {
     $this->db->connect();
     $product_list = array();
     $sql = "SELECT * from tbl_products";
     $result = $this->db->fetchQuery($sql);
     if ($result->num_rows > 0) {
         while ($row = $result->fetch_assoc()) {
             $product = new Product();
             $product->set_id($row['id']);
             $product->set_name($row['name']);
             $product->set_description($row['description']);
             $product->set_sell_price($row['sell_price']);
             $product->set_cost_price($row['cost_price']);
             $product->set_photo($row['photo']);
             $product->set_added_date($row['added_date']);
             $product->set_modified_date($row['modified_date']);
             $product->set_status($row['status']);
             array_push($product_list, $product);
         }
     }
     $this->db->close();
     return $product_list;
 }