I code part as below :

class Selection(models.Model):
    _name = 'selection.model' 
    _rec_name = 'select'
    select = fields.Char(string='selections', required=True)

class Checks(models.Model):
    _name = 'buy.goods' 
    strs = fields.Char()
    results = fields.Many2one('selection.model', string='Selections')

    @api.onchange('strs')
    def _get_results(self): 
        goods = self.strs.split(',')
        ...
I want to show all items of 'goods' as selections of 'results' field; and when 'strs' field is changed, the selections of 'results' field should be updated at once. so how shall I code for this?