def _pre_put_hook(self): sensor = Sensor.query(Sensor.sensor_id == self.sensor_id).fetch(1) if not sensor: sensor = Sensor(sensor_id=self.sensor_id) sensor.put() else: sensor = sensor[0] # calculate real value if sensor.type == Sensor.DISTANCE: v = float(self.raw) / 4096 * 3 * 1.4 self.value = 76.35 * (math.e ** (-3.469 * v)) + 17.3 * (math.e ** (-0.5599 * v))