Get a value out of a MQTT string to a number

I use OH4.0.3 and I made a MQTT connection to my Victron Carbon GX. The connection works fine and tested also with MQTT explorer.
I made the MQTT Broker and a Thing with Channel and Items.
But I get only the value {“value”: 43.0} back and it works only if the channel is setup as string and also the item as string. With number it don’t works.
Sorry for maybe a easy or stupid question, but I’m a beginner in MQTT and only thing is I want to get some values out ob my Victron Carbon GX for further rules. I don’t couldn’t find a solution in the different chats and communities. Maybe someone can easy help me and give me a detailed information how it could work.
Thanks a lot and best regards

Create a number channel and use transformati onPattern="JSONPATH:$.value"
Then link that to a number item.

Please be aware that JSONPath Transformation Service has to be installed :slight_smile: