Martin,

What you can do is,

• Inherit form view of sale.order having user_id field and add onchange attribute to it as:

• • <field name="user_id" position="attributes">

  • • <attribute name="on_change">on_saler_change(user_id)</attribute>

  • </field>

• in .py inherit sale.order using old api only and define "on_saler_change(user_id)" in it

• 
  

Hope it helps!    

Hello Martin,

If this onchange method is from base module then call super for the same method.

from openerp import models, fields, api, _

from openerp.exceptions import UserError

class Order(models.Model):

    _inherit = 'sale.order'

    @api.onchange('user_id')

    def on_saler_change(self):

        raise UserError(_('Something Happened'))

        return super(Order, self).on_saler_change()

Hope it works for you.

Thanks,