based on below code am fetching uid data from RFID tag(Hardware Device) through mqtt broker but it is not storing in database 
import paho.mqtt.client as mqtt
class iot(models.Model):
     _name = 'iot.iot'
     name = fields.Char()
     uid=fields.Char()
     global mqttc

     mqttc = mqtt.Client("python_pub")
     mqttc.connect("172.16.73.4", 1883)
     mqttc.publish("light", "light subscribed")
     print "mqtt"


     def on_message(client, userdata, message):
            print("message received ", str(message.payload.decode("utf-8")))
            global uid
            uid=str(message.payload.decode("utf-8"))
              
     mqttc.on_message = on_message
     mqttc.loop_start()
     mqttc.subscribe("sub")

     In on_message method self object not available so give me suggestion how to store uid data in database