How to create item by content?

[rossko57]

One way to do this would be to accept the MQTT JSON into a String Item.
Trigger a rule from Item change, analyse the JSON and update the target Items as required.

There is also a different approach here, using a REGEX in Items MQTT-1 binding. I’m not sure if you can do this with MQTT-2 (channels)

[SOLVED] REGEX im MQTT item

OK, I have got this to work now. I had two different streams of data on the same MQTT topic - power useage which was logged every 5 seconds and was constantly changing, and the oil tank level which logged every 15 minutes and only changed every one or two days. I didn’t realise that OpenHAB only logs an event if the MQTT data changes, but once I published the data manually using mosquitto_pub -h localhost -i RTL_433 -t RTL_433/JSON -m '{"time" : "2017-12-29 09:52:32", "model" : "Oil Watchman", …

Edit - this outlines the way for MQTT-2 I think, but you’ll need the 2.5 binding

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…