transformationPattern of MQTT-Channel is ignored

  • Platform information:
    • Hardware: Raspi 4, ConBee II
    • OS: Raspbian
    • Java Runtime Environment: openjdk11
    • openHAB version: openHAB 3.0.2 Release Build

Hey there,
I use the MQTT-Binding together with zigbee2mqtt (which shouldn’t matter, just for completion) and a mosquitto broker.

First I created a MQTT Broker Thing and set up the connection.
To then add a device I configured a Generic MQTT Thing, and add a channel (as well as an Item to hold the value):

UID: mqtt:topic:8e28935d28:e00b881b84
label: TRADFRI Remote Control
thingTypeUID: mqtt:topic
configuration: {}
bridgeUID: mqtt:broker:8e28935d28
  - id: zGfEOsP7J6
    channelTypeUID: mqtt:string
    label: Action
    description: ""
      stateTopic: zigbee2mqtt/0x588e81fffe032c3c

I now can receive the payload of the added device (a remote control):

  "action": "toggle",
  "battery": 87,
  "linkquality": 255,
  "update": {
    "state": "idle"
  "update_available": false

However, if I try to use the transformationPattern property, it doesn’t work.
I try to set transformationPattern: JSONPATH:$.action but it is just ignored and the Item just holds the entire payload instead of just the value of action.

best regards gkhaos

What do the logs say? Have you installed the JSONPATH Transformation Service within openHAB?

If you do, please show your Thing and Item configuration.


Have a look here and compare if your setup is the same (I posted some screenshot of one of my items using JSON).
As well, did you install JSONPATH transformation?

Sorry for the late reply, but yes, the problem was the absence of the JSONPATH Transformation Service. Thanks alot :slight_smile: