cambiar coste por variante en vez de template

purchase.py

@@ -13,7 +13,7 @@ class account_invoice(models.Model):
             if product:
                 template = self.env['product.template'].browse(product.product_tmpl_id.id)
                 if(template.price_change == 'purchase'):
-                    template.write({'standard_price': item.price_unit, 'last_purchase_date': date.today()})
+                    product.write({'standard_price': item.price_unit, 'last_purchase_date': date.today()})
                 else:
-                    template.write({'last_purchase_date': date.today()})
+                    product.write({'last_purchase_date': date.today()})
         return res