namhoc.py

    @api.model
    def _get_list_namhoc(self):
        lst_namhoc=[]
        for year in range(1990,2050):
            item = str(year) + "-" + str(year+1)
            lst_namhoc.append( (item, item) )
        return lst_namhoc

    @api.model
    def _get_namhoc_now(self):
        now = datetime.datetime.now()
        year = now.year
        if now.month <= 9:
            year -= 1
        return str(year) + "-" + str(year+1)

    namhoc = fields.Selection(
        string="Năm học",
        selection= _get_list_namhoc,
        default = _get_namhoc_now,
    )