university-final-iot-backend/app/devices/mqtt_client.py

96 lines
3.0 KiB
Python

import sys
import json
from flask_mqtt import Mqtt
from .models import Recording
from app import db, app
class MqttClient:
class __MqttClient:
def __init__(self):
self.mqtt = Mqtt()
self.initialized = False
def __str__(self):
return repr(self)
instance = None
def __init__(self):
if not MqttClient.instance:
MqttClient.instance = MqttClient.__MqttClient()
def __getattr__(self, name):
return getattr(self.instance, name)
# Mqtt setup
def setup(self, app):
if not self.initialized:
self.mqtt.init_app(app)
self.mqtt.client.on_message = self.handle_mqtt_message
self.mqtt.client.on_subscribe = self.handle_subscribe
initialized = True
@self.mqtt.on_connect()
def handle_connect(client, userdata, flags, rc):
print('MQTT client connected')
self.mqtt.subscribe('device/+')
@self.mqtt.on_disconnect()
def handle_disconnect():
print('MQTT client disconnected')
print('MQTT client initialized')
def tear_down(self):
self.mqtt.unsubscribe_all()
if hasattr(self.mqtt, 'client') and self.mqtt.client is not None:
self.mqtt.client.disconnect()
print('MQTT client destroyed')
def handle_subscribe(self, client, userdata, mid, granted_qos):
print('MQTT client subscribed')
def handle_mqtt_message(self, client, userdata, message):
print("Received message!")
print("Topic: " + message.topic)
print("Payload: " + message.payload.decode())
try:
# If type is JSON
recording = self.parse_json_message(message.topic, message.payload.decode())
with app.app_context():
recording.save()
except ValueError:
print("ERROR!")
error_type, error_instance, traceback = sys.exc_info()
print("Type: " + str(error_type))
print("Instance: " + str(error_instance))
return
def parse_json_message(self, topic, payload) -> Recording:
try:
json_msg = json.loads(payload)
device_id = self.get_device_id(topic)
return Recording(device_id=device_id,
record_type=json_msg["record_type"],
record_value=json_msg["record_value"],
recorded_at=json_msg["recorded_at"],
raw_json=json_msg)
except KeyError:
error_type, error_instance, traceback = sys.exc_info()
raise ValueError("JSON parsing failed! Key error: "
+ str(error_instance))
def get_device_id(self, topic) -> int:
device_token, device_id = topic.split("/")
if device_token == "device":
return int(device_id)
else:
raise ValueError("Topic is in invalid format")