OH3 Reading MQTT values

[rossko57]

@travellingkiwi

I’m not sure whether the GUI has a separate filter

It does not. Nothing to do with GUI or REGEX directly, the OH1 binding offered separate parameters for ‘transformation’ and for ‘filtering’. OH2 binding (as carried forward to OH3) only has transformation.
Wahh!
That’s okay, the OH2/3 binding offers chained transformations to pull off exactly the same trick (and be more flexible in other uses).
Typically users might use a REGEX to select messages containing a magic serial number, then if found chain on another transform to select a data field -usually by JSONPATH, but if want to use another REGEX of course you can.

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…

@travellingkiwi

Annoyingly the regex still has to match the whole string.

Yes, REGEX transformation service is unchanged.