clinic/netforce_clinic/models/nation.py

from netforce.model import Model, fields

class Nation(Model):
    _name="clinic.nation"
    _string="Nationality"
    _key=['code']

    _fields={
        "name": fields.Char("Name",required=True,search=True),
        "code": fields.Char("Code",search=True),
        'default': fields.Boolean("Default"),
    }

    def write(self,ids,vals,**kw):
        default=vals.get('default')
        if default:
            for obj in self.search_browse([]):
                if obj.id not in ids:
                    obj.write({
                        'default': False,
                    })
        super().write(ids,vals,**kw)

Nation.register()