Hi,

Just change the name of the function and write down as like below.

def _default_bp(self, cr, uid, context = None):   

    .... your code for bp ....

    return 'any string'

def _default_cd(self, cr, uid, context = None):    

    .... your code for cd ....

    return 'any string'

_columns = {

                'ma_nv':fields.many2one('danh.sach.nv', 'Mã NV'),
                'ten_nv':fields.char( 'Tên nhân viên', size = 30),
                'ngay_sinh':fields.date('Ngày sinh'),
                'ten_bp':fields.char('Bộ phận', size = 30),
                
                'ten_cd':fields.char( 'Chức danh', size = 30),
               
                'ly_do_huy': fields.char('Lý do hủy hợp đồng', size = 100),
                'ngay_huy':fields.date('Ngày hủy'),
                
                }
    _defaults = {
                 'ten_bp': _default_bp,
                 'ten_cd' : _default_cd
                 }

Thanks Chirag. But I tried it. my code .py

    def _get_bp(self, cr, uid, *args):
        try:
            proxy = self.pool.get('danh.sach.nv').browse(cr, uid, ids).ma_nv
            md = self.browse(cr, uid, ids).ma_nv
            if proxy==md :
                res['ten_bp'] = proxy.ten_bp
            return {'value': res}
        except Exception, ex:
            return False 

But it did not work. I dont know I have error. Can you help me?

You are mixing up function fields, on_change methods and default methods.

What you try to do is setting default values with a function. The syntax for that is the one that chirag pointed out. Use it!

Further it looks like ten_bp should default to a value that has something to do with  danh.sach.nv (ma_nv), but you must not forget, that the default values will be calculated on the creation of a record. Thus there is no related ma_nv assigned to the new object yet. You can not browse a record that has not yet been created.