gmqtt

0.7.0 verified Fri May 01 auth: no python

Asynchronous MQTT client for Python (3.5+) using asyncio. Supports QoS 0/1/2, TLS, WebSocket, and MQTT v5.0. Maintained by Wialon. Current version 0.7.0, with irregular releases (last in 2023).

pip install gmqtt

Common errors

error TypeError: on_message() takes 4 positional arguments but 5 were given ↓

cause Callback signature expects 4 arguments but gmqtt 0.7.0 passes 5 (added 'properties').

fix

Update callback to def on_message(client, topic, payload, qos, properties): ....

error AttributeError: 'Client' object has no attribute '_on_connect' ↓

cause Trying to monkey-patch internal attribute; gmqtt uses public callback `on_connect` with underscore prefix removed.

fix

Use client.on_connect = lambda client, flags, rc, properties: ... (5 args).

error ModuleNotFoundError: No module named 'gmqtt' ↓

cause Not installed or installed in a different environment.

fix

Run pip install gmqtt in the correct Python environment.

Warnings

breaking In version 0.7.0, `on_message` signature changed: new parameter `properties` added. Old code with `client.on_message = on_message(client, topic, payload, qos)` will raise TypeError. ↓

fix Update callback to accept 5 arguments: client, topic, payload, qos, properties.

gotcha Using `Client` class without calling `set_auth_credentials` when broker requires auth will silently disconnect. No error is raised until publish/subscribe fails. ↓

fix Always call `set_auth_credentials(username, password)` if broker expects authentication.

gotcha Connecting with the same `client_id` to a broker that has session present can cause the previous session to be taken over. The client might not receive messages until reconnection completes. ↓

fix Use unique client IDs or set `clean_session=True` when connecting.

Imports

Client
```
from gmqtt import Client
```
Main class for creating MQTT clients.
Message
```
from gmqtt import Message
```
Represents an MQTT message.

Quickstart

Basic connect, subscribe, publish with authentication.

import asyncio
import os
from gmqtt import Client as MQTTClient

async def main():
    client = MQTTClient("client_id")
    client.set_auth_credentials(os.environ.get('MQTT_USER', ''), os.environ.get('MQTT_PASS', ''))
    # Set callbacks
    def on_message(client, topic, payload, qos, properties):
        print(f"Received: {topic} -> {payload}")
    client.on_message = on_message
    await client.connect('localhost', 1883)
    client.subscribe('test/topic')
    client.publish('test/topic', 'hello')
    await asyncio.sleep(2)
    await client.disconnect()

if __name__ == '__main__':
    asyncio.run(main())