msg->get_properties() not working in message_arrived

[greg887]

Is there a bug in msg->get_properties() ?
Am I doing anything wrong?
I looked at the properties samples and I'm using it in the same way.
I tried different brokers thinking something in the broker could be wrong and I get the same results. I also installed the latest mosquitto broker in my laptop and used localhost as broker and it didn't work.

properties in paho cpp are not working when I use msg->get_properties() in message_arrived, but properties in message_arrive work in python.
I run both subscribers the python version and the cpp version at the same time subscribing to the same topic (the publisher is in c++)

** Subscriber python version output:**
Received message: Hello, MQTT! on topic ggg/test/topic
Message Properties:
[UserProperty : [('key1', 'value1'), ('key2', 'value2')]]

** Subscriber c++ output:**
Message arrived: ggg/test/topic -> Hello, MQTT!
No hay user property, porqueeee?? (This means "There is no user property, whyyyy?" )
Is props empty? '1'
props size: '0'

Below is my c++ subscriber message_arrived code
` void message_arrived(mqtt::const_message_ptr msg) override {
std::cout << "Message arrived: " << msg->get_topic() << " -> " << msg->to_string() << std::endl;

    const mqtt::properties& props = msg->get_properties();

    if (props.contains(mqtt::property::USER_PROPERTY)){
        std::cout << "Lo logrè, mamà\n" << std::endl;
    }
    else {
        std::cout << "No hay user property, porqueeee??" << std::endl;
    }

    std::cout << "Is props empty? '" << props.empty() << "'" << std::endl;
    std::cout << "props size: '" << props.size() << "'" << std::endl;

}`

Please kindly help!

[fpagliughi]

I was working on properties recently. Hopefully I didn’t add a bug.

What version of the library are you using?

[greg887]

const uint32_t VERSION = 0x01030001;
/** The version string for the client library  */
const string VERSION_STR("Paho MQTT C++ (mqttpp) v. 1.3.1");

thanks for all the amazing work!

[fpagliughi]

It seems to be working fine in the latest 'develop' branch, which I'm working on at the moment (for the next v1.5 release). I'll double check v1.3.1 to see what I can can find, but I don't see any modifications in the message class that would explain it; nor anything in the changelog mentioning a fix.

But just FYI, I've recently dropped a bunch of stuff in the code to make it easier to deal with properties on incoming messages and server responses. Like an iterator for properties and a few more methods to get it to act like an STL collection, like begin(), end(), etc. Plus a stream inserter for property for printing them out.

[greg887]

I just installed v1.4.0 and I'm still getting the same error, I removed paho 1.3.1 and re-install paho.

Do you have any estimate of when v1.5 could be released?

Those are going to be great features.

Thanks!

[fpagliughi]

Sorry. Totally forgot about this. I’ll verify as part of the next patch release to see if it was actually fixed.

[fpagliughi]

Apologies. I was never able to recreate this problem, so I decided to make a new example app, async_subscribe_v5 to show it working.

When I made the example app, I had the same problem! No properties. But then I realized that I was connecting to the broker and requesting an MQTT v3.1.1 connection. So I was getting the messages, but no properties in them.

I suspect, maybe, that's what you did... connected using MQTT v3.x.

When you do that, you still get messages that a v5 producer sent to the broker, but you get them with the v5 properties and reason code stripped out.

[greg887]

I'll check within this week or next week and let you know what I could see, but thanks for the insight.