Extract value (number) from node red payload?

General
1

Greetings!
I have problems with my Shelly dimmer 2. I have set it up over mqtt. Everything works great except dimming slider value. Dimming slider works great when I am using it, but I wan't that slider pick up the value from shelly dimmer when it is dimmed somewhere else.
I have subscribed to MQTT topic "shellies/shellydimmer2-D8BFC01A040E/light/0/status" and when I dimm it somewhere else I get this on debug node

shellies/shellydimmer2-D8BFC01A040E/light/0/status : msg : Object

object

topic: "shellies/shellydimmer2-D8BFC01A040E/light/0/status"

payload: "{"ison":true,"has_timer":false,"timer_started":0,"timer_duration":0,"timer_remaining":0,"mode":"white","brightness":16}"

qos: 0

retain: false

_msgid: "14b5cdb.c291e32"

I would like to get only the value "brightness":16 or any other value of brightness to output as number so I can send that number to slider node.

Can someone help me?

Thank you!

2

Hello & welcome to the fourm.

So a small lesson on JS objects and their equivalent string representation (AKA JSON)...

Your payload is a string/JSON (due to the Output setting on the MQTT node). You could attempt some complex splits and loops etc - but - as it is JSON (JavaScript Object Notation) - just let JS do its thing - turn that JSON back into a JS Object! (if you dont know what I mean, it'd be worth reading up - will help you greatly in node-red knowing the difference)

So first off, change your MQTT IN to...
image
... then you will be able to simply "copy path" to any item

There’s a great page in the docs that will explain how to use the debug panel to find the right path to any data item.

https://nodered.org/docs/user-guide/messages

3

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