Mqtt handleAction and handleWriteProperty do not work as expected

[hasanheroglu]

https://github.com/eclipse/thingweb.node-wot/blob/09dfd6ab03805b7b39ab39433880496466d25e67/packages/binding-mqtt/src/mqtt-broker-server.ts#L269

https://github.com/eclipse/thingweb.node-wot/blob/09dfd6ab03805b7b39ab39433880496466d25e67/packages/binding-mqtt/src/mqtt-broker-server.ts#L303

The lines above send just a JSON object or string (in case of a parsing error for handleAction) to handleInvokeAction and handleWriteProperty function, where functions need a Content object instead. And with these non-Content values InteractionOutputs are created, after we make a call for InteractionOutputs value error occurs because InteractionOutputs content is not actually a content but JSON object or string.

I have seen that for other protocol bindings using forms' contentType, Content object is created:
https://github.com/eclipse/thingweb.node-wot/blob/09dfd6ab03805b7b39ab39433880496466d25e67/packages/binding-coap/src/coap-server.ts#L456-L460

Should we also apply same kind of logic here or should we follow some other method?

[danielpeintner]

I did not look into it more closely but it seems to be a left over from "very old" times.

As mentioned in another issue, I think we should come up with tests that actually "check" interactions with values in MQTT to be sure that everything works as expected.
A PR with a fix and tests is appreciated 👍

[egekorkan]

For clarification: The JSON.parse way is predating all the other packages that use Content. MQTT package should do the same.

[hasanheroglu]

Working on it.