add example code

Author: vladak

examples/cpython/user_data.py

@@ -0,0 +1,98 @@
+#!/usr/bin/env python3
+
+# pylint: disable=logging-fstring-interpolation
+
+"""
+Demonstrate on how to use user_data for various callbacks.
+"""
+
+import logging
+import socket
+import ssl
+import sys
+
+import adafruit_minimqtt.adafruit_minimqtt as MQTT
+
+
+# pylint: disable=unused-argument
+def on_connect(mqtt_client, user_data, flags, ret_code):
+    """
+    connect callback
+    """
+    logger = logging.getLogger(__name__)
+    logger.debug("Connected to MQTT Broker!")
+    logger.debug(f"Flags: {flags}\n RC: {ret_code}")
+
+
+# pylint: disable=unused-argument
+def on_subscribe(mqtt_client, user_data, topic, granted_qos):
+    """
+    subscribe callback
+    """
+    logger = logging.getLogger(__name__)
+    logger.debug(f"Subscribed to {topic} with QOS level {granted_qos}")
+
+
+def on_message(client, topic, message):
+    """
+    received message callback
+    """
+    logger = logging.getLogger(__name__)
+    logger.debug(f"New message on topic {topic}: {message}")
+
+    messages = client.user_data
+    if not messages.get(topic):
+        messages[topic] = []
+    messages[topic].append(message)
+
+
+# pylint: disable=too-many-statements,too-many-locals
+def main():
+    """
+    Main loop.
+    """
+
+    logging.basicConfig()
+    logger = logging.getLogger(__name__)
+    logger.setLevel(logging.DEBUG)
+
+    # dictionary/map of topic to list of messages
+    messages = {}
+
+    # connect to MQTT broker
+    mqtt = MQTT.MQTT(
+        broker="172.40.0.3",
+        port=1883,
+        socket_pool=socket,
+        ssl_context=ssl.create_default_context(),
+        user_data=messages,
+    )
+
+    mqtt.on_connect = on_connect
+    mqtt.on_subscribe = on_subscribe
+    mqtt.on_message = on_message
+
+    logger.info("Connecting to MQTT broker")
+    mqtt.connect()
+    logger.info("Subscribing")
+    mqtt.subscribe("foo/#", qos=0)
+    mqtt.add_topic_callback("foo/bar", on_message)
+
+    i = 0
+    while True:
+        i += 1
+        logger.debug(f"Loop {i}")
+        # Make sure to stay connected to the broker e.g. in case of keep alive.
+        mqtt.loop(1)
+
+        for topic, msg_list in messages.items():
+            logger.info(f"Got {len(msg_list)} messages from topic {topic}")
+            for msg_cnt, msg in enumerate(msg_list):
+                logger.debug(f"#{msg_cnt}: {msg}")
+
+
+if __name__ == "__main__":
+    try:
+        main()
+    except KeyboardInterrupt:
+        sys.exit(0)