purchase_line_reference_athletic/purchase_reference.py

# -*- encoding: utf-8 -*-
from openerp import models,fields,api

class purchase_order_line(models.Model):
    _name = 'purchase.order.line'
    _inherit = 'purchase.order.line'

    #obtener referencia
    @api.one
    @api.onchange('product_id')
    def _get_factory_reference(self):
        self.product_factory_ref = self.product_id.factory_reference

    #campo
    product_factory_ref = fields.Char(string='Referencia de fábrica', compute='_get_factory_reference')