I have some fields which will be available only for permitted group users. I have a configuration screen where user can select the groups to be assigned .

My model is like  this:

class service_config(models.Model):     
        _name = 'service.config'
        service_type=fields.Selection(selection=[('1', 'Service type 1'),('2', 'Service Type 2')])
        authorized_group = fields.Many2many('res.groups')

In another model i have certain fields as per the service type and those fields should be accessible by the authorised group users only. How to achieve this ?

I know how to assign group permission over a field when i already know the groups but how to configure it when the groups are being set dynamically and stored in another model.  I have no control over which groups will be chosen

Any ideas.. please help.