# -*- coding: utf-8 -*-
from openerp.osv import fields, osv

class product_template2(osv.osv):

  _name = 'product.template'
  _inherit = 'product.template'

  _columns = {
       'default_code': fields.related('product_variant_ids', 'default_code', type='char', string='Internal Reference'), 
  }

product_template2()

 
# -*- coding: utf-8 -*-
{
    'name': "Add Internal Reference",

    'summary': """Add Internal Reference field to standard forms.""",

    'description': """
        Adds the default internal reference field to forms so it is visible.
        This is used for internal part numbers so access to this is important.
    """,

    'author': "Peck Tech Consulting Ltd.",
    'website': "http://www.pecktech.ca",
    'category': 'Tool',
    'version': '0.1',
    'depends': ['product'],
    'data': ['addIntRef.xml'],
    'demo': [],
}

 
<?xml version="1.0"?>
<openerp>
 <data>
  <record id="product.product_template_tree_view2" model="ir.ui.view">
   <field name="name">product.template.product.tree2</field>
   <field name="model">product.template</field>
   <field name="inherit_id" ref="product.product_template_tree_view"/>
   <field name="arch" type="xml">
    <xpath expr="//field[@name='name']" position="before">
     <field name="default_code"/>
    </xpath>
   </field>
  </record>
 </data>
</openerp>