Async function inside MQTT message event - node.js

Question

I'm using MQTTjs module in a Node app to subscribe to an MQTT broker.
I want, upon receiving new messages, to store them in MongoDB with async functions.
My code is something as:
client.on('message', (topic, payload, packet) => {
(async () => {
await msgMQTT.handleMQTT_messages(topic, payload, process.env.STORAGE,
MongoDBClient)
})
})
But I can't understand why it does not work, i.e. it executes the async function but any MongoDB query returns without being executed. Apparently no error is issued.
What am I missing?

Answer 1

I modified the code in:
client.on('message', (topic, payload, packet) => {
try {
msgMQTT.handleMQTT_messages(topic, payload, process.env.STORAGE,
MongoDBClient, db)
} catch (error) {
console.error(error)
}
})
Where:
exports.handleMQTT_messages = (topic, payload, storageType, mongoClient, db) => {
const dateFormat = 'YYYY-MMM-dddd HH:mm:ss'
// topic is in the form
//
const topics = topic.split('/')
// locations info are at second position after splitting by /
const coord = topics[2].split(",")
// build up station object containing GeoJSON + station name
//`Station_long${coord[0]}_lat${coord[1]}`
const stationObj = getStationLocs(coord.toString())
const msg = JSON.parse(payload)
// what follows report/portici/
const current_topic = topics.slice(2).join()
let data_parsed = null
// parse only messages having a 'd' property
if (msg.hasOwnProperty('d')) {
console.log(`${moment().format(dateFormat)} - ${stationObj.name} (topic:${current_topic})\n `)
data_parsed = parseMessages(msg)
// date rounded down to the nearest hour
// https://stackoverflow.com/questions/17691202/round-up-round-down-a-momentjs-moment-to-nearest-minute
dateISO_String = moment(data_parsed.t).startOf('hour').toISOString();
// remove AQ from station name using regex
let station_number = stationObj.name.match(/[^AQ]/).join('')
let data_to_save = {
id: set_custom_id(stationObj.name, dateISO_String),
//`${station_number}${moment(dateISO_String).format('YMDH')}`,
date: dateISO_String,
station: stationObj,
samples: [data_parsed]
}
switch (storageType) {
case 'lowdb':
update_insertData(db, data_to_save, coll_name)
break;
case 'mongodb': // MongoDB Replicaset
(async () => {
updateIoTBucket(data_to_save, mongoClient, db_name, coll_name)
})()
break;
default: //ndjson format
(async () => {
await fsp.appendFile(process.env.PATH_FILE_NDJSON,
JSON.stringify(data_to_save) + '\n')
})()
//saveToFile(JSON.stringify(data_to_save), process.env.PATH_FILE_NDJSON)
break;
}
// show raw messages (not parsed)
const show_raw = true
const enable_console_log = true
if (msg && enable_console_log) {
if (show_raw) {
console.log('----------RAW data--------------')
console.log(JSON.stringify(msg, null, 2))
console.log('--------------------------------')
}
if (show_raw && data_parsed) {
console.log('----------PARSED data-----------')
console.log(JSON.stringify(data_parsed, null, 2))
console.log('--------------------------------')
}
}
}
}
Only updateIoTBucket(data_to_save, mongoClient, db_name, coll_name) is executed asynchrounsly using mgongodb driver.