Transform in Rule

[chrissaich]

Hi

Hope you all had a good Christmas. For me it’s too much food and not enough coding.

I have a system working happily on RPI4 running OpenHAB 3 with Mosquitto MQTT Broker running and communicating on the same RPI4.

I have a number of temperature inputs which will send me a topic of

occ/location/ti

and the payload will be the number of the temperature sensor 1-8, followed by a ‘:’ followed by the temperature value, so a typical payload might be

1:11.6

Can somebody show me a rule which will allow me to ‘Switch/case’ on the first digit and extract the temperature value to forward to the relevant UI location?

Thanks as ever

[hafniumzinc (T)]

You might be able to do this in your Thing Channel directly without a rule by using REGEX to filter for the sensor by looking for

1:

then chaining another REGEX transform to extract the temperature value. All of this would go in the transformationPattern of the Thing Channel. You can then create a separate Channel for each temperature sensor, adjusting your first REGEX filter to suit.

This may help:

MQTT 2.5 M1+ How to implement the equivalent to MQTT1 REGEX filters

Problem In the MQTT1 binding there was a feature that let us filter messages published to a given topic and only pass those that match a given REGEX to the transformation and/or on to the Item. This was useful to handle devices that publish messages to a single well known topic for all their devices. For example, the official firmware from the vendor of Shelly devices have a request/response protocol over MQTT to get meta data about the devices (IP address, MAC address, firmware version, whethe…

[rossko57]

@chrissaich

Can somebody show me a rule which will allow me to ‘Switch/case’ on the first digit

If you must go that way, string .split(":") would be useful.
But I’d direct effort at doing it in the channel(s) by transformation, as suggested by @hafniumzinc