[SOLVED] [JSR223][Jython]MQTT Channel Trigger

  • Platform information:
    • Hardware: Raspberry Pi 3 B+, 120gb mSATA SSD in a USB enclosure
    • OS: Raspbian Stretch
    • Java Runtime Environment: 1.8.0_212
    • openHAB version: 2.4.0 release build. Jython 2.7.0

Today seemed like a good day to start down the MQTT route for the first time.
I tried for a while (mistakenly) to follow Openhab 1.x tutorials to define subscriptions directly in items, and of course got nowhere. Once I figured out why (wrong Openhab version, completely different architecture) I found this example which seemed like the closest way to get multiple topics MQTT messages into a jython script for further processing.

So, here’s my question.

Why does this work just fine:

rule "Topic and Payload"
    Channel "mqtt:broker:local:LivingRoom433" triggered
    var rawevent = receivedEvent.toString.split(" ").get(2).split("#")
    var topic = rawevent.get(0)
    var payload = rawevent.get(1)
    logInfo("Topic", topic + ", " + payload)

But this results in an error as below:

@rule("MyRule", description="", tags=["utility"])
@when("Channel mqtt:broker:local:LivingRoom433 triggered")
def MyRule_Decorators(event):
2019-06-23 21:21:28.753 [INFO ] [rt.internal.loader.ScriptFileWatcher] - Loading script 'python/personal/kitchen_fans/kitchen_fans.py'
2019-06-23 21:21:28.860 [ERROR] [jsr223.jython.core.triggers         ] - when: Exception [when: "Channel mqtt:broker:local:LivingRoom433 triggered" could not be parsed because Channel "mqtt:broker:local:LivingRoom433" is not a trigger]: [Traceback (most recent call last):
  File "/etc/openhab2/automation/lib/python/core/triggers.py", line 370, in when
    raise ValueError("when: \"{}\" could not be parsed because Channel \"{}\" is not a trigger".format(target, trigger_target))
ValueError: when: "Channel mqtt:broker:local:LivingRoom433 triggered" could not be parsed because Channel "mqtt:broker:local:LivingRoom433" is not a trigger
2019-06-23 21:21:28.867 [ERROR] [ipt.internal.ScriptEngineManagerImpl] - Error during evaluation of script 'file:/etc/openhab2/automation/jsr223/python/personal/kitchen_fans/kitchen_fans.py': TypeError: 'NoneType' object is not callable in <script> at line number 33 

What am I missing?

I ran into the same issue. Have a look here:

I solved it in the second post. You need to comment out the line in triggers.py mentioned in the error message.
It’s a problem with the type declaration of the mqtt trigger channel.
Ever since commenting out those lines the mqtt eventbus rules have been working great for me in jython.
Best regard Johannes

1 Like

THANK YOU! That did it. :slight_smile:

1 Like

Hey @JGKK, while you’re here, since you know your way around MQTT, any chance you could give me some pointers on this question too? :slight_smile:

For completeness, the MQTT2 binding has a bug that causes the issue…