how i get  class site_survey(models.Model): id in another class class site_survey_cancellation(models.TransientModel):

code is below

class site_survey(models.Model):
    _name = 'site.survey'
    name = fields.Char(readonly=True)
    @api.multi

def action_cancel(self):
   # self.state = 'cancel'
    self._context
    return {
        'name': ('Cancel Reason'),
        'view_type': 'form',
        'view_mode': 'form',
        'res_model': 'site.survey.cancellation',
        'view_id': False,
        'type': 'ir.actions.act_window',
        'target': 'new',
        'res_id':self._context
    }

class site_survey_cancellation(models.TransientModel):
    _name = 'site.survey.cancellation'
    cancel_note = fields.Char("Cancel Reason")
    site_survey_id = ??????