Hi!

I'm trying to extend hr_employee to add a couple of fields, one of those to show how many one2many items has an employee linked. 

------------------------
from openerp import models, fields, api

class hr_employee(models.Model):
    _name = 'hr.employee'
    _inherit = ['hr.employee']

    employee_session_ids = fields.One2many('session.session', 'employee_id')
    employee_session_count = fields.Integer(string="Session Items", coumpute='_employee_session_count')

    @api.one
    @api.depends('employee_session_ids')
    def _employee_session_count(self):
        self.employee_session_count = len(self.employee_session_ids)
------------------------

'session.session' is implemented with new api syntax. And I've managed to do it well when all classes involved are in the new syntax. But if I inherit an old class the method is not invoked.

I've misunderstood the operation of the api decorators, probably. I tried to decorate the method with @api.model and @api.returns but it doesn't work.

------
    @api.one
    @api.model
    @api.returns('hr.employee', lambda val: val.id)
    @api.depends('employee_session_ids')
    def _employee_session_count(self):
        self.employee_session_count = len(self.employee_session_ids)
------

Any clue?