Mqtt subscription - No notify with topic subscription, using '+' and '#' together

nicolobracchi40

We noticed that when we try to send a topic via MQTT in our QT (6.5.2) quick application, we get an error using Multi-level wildcard ('#'), and Single-level wildcard ('+'), both in the same topic.

Example:
if our app subscribes this topic:

"persint/1/+/msa/#"

and via MQTT Explorer we publish:

"persint/1/2/msa/3"

the app is not notified.

How to fix it?

This is the link of MQTT doc:

https://docs.oasis-open.org/mqtt/mqtt/v5.0/mqtt-v5.0.pdf

and this is an app example with relative output:

QMqttTopicFilter globalFilter{"foo/+/#"};
    QMqttTopicName topicName("foo/pippo/bar");
    if(globalFilter.isValid()) {
        qDebug() << "FILTER VALID";
        if (globalFilter.match(topicName)) {
            qDebug() << "TOPIC MATCH";
        }
        else {
            qDebug() << "TOPIC NO MATCH";
        }
    }
    else {
        qDebug() << "FILTER NOT VALID";
    }

and the output is:

FILTER VALID
TOPIC NO MATCH

JKSH

Hi @nicolobracchi40, and welcome!

This looks like a bug. See https://bugreports.qt.io/browse/QTBUG-104478