Filter out Object Information

[TridiumControls]

Hi, 

How do I go about splitting this information? I mainly care about the oldState and currentState. Preferably to be 2 outputs inside a function block so that I can map the outputs to a modbus write. 

zwave: value changed : msg : Object

object

topic: "zwave: value changed"

payload: object

nodeid: 3

cmdclass: 38

cmdidx: 0

instance: 1

oldState: 1

currState: 50

label: "Level"

units: ""

value: object

value_id: "3-38-1-0"

node_id: 3

class_id: 38

type: "byte"

genre: "user"

instance: 1

index: 0

label: "Level"

units: ""

help: ""

read_only: false

write_only: false

min: 0

max: 255

is_polled: false

value: 50

[TridiumControls]

I went ahead and ran it through JSON node. How would I go bout and extracting information from JSON?

zwave: value changed : msg.payload : string[372]

"{"nodeid":3,"cmdclass":38,"cmdidx":0,"instance":1,"oldState":44,"currState":99,"label":"Level","units":"","value":{"value_id":"3-38-1-0","node_id":3,"class_id":38,"type":"byte","genre":"user","instance":1,"index":0,"label":"Level","units":"","help":"","read_only":false,"write_only":false,"min":0,"max":255,"is_polled":false,"value":99},"uuid":"12312344412341234"}"

[Nick O'Leary]

Given your original message (forget about converting it to a single string... that makes it unnecessarily harder) you can access the two properties as:

msg.payload.oldState
and
msg.payload.currState

So if you have a function with two outputs, you can do:

var M1 = {
    payload: msg.payload.oldState
};
var M2 = {
    payload: msg.payload.currState
};
return [M1, M2];

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[Julian Knight]

JSONata via the change node is good for that kind of manipulation - though, as Nick says, if you just want a couple of attributes, a function node is a simple way of doing it.

[TridiumControls]

Thanks Nick and Julian,

That makes sense.

My apologies Nick, didn't see your reply. Went to spam for some reason.

I'm taking a few Java scripting classes, and won't be asking these easy questions here. Appreciate you taking the time to reply. I'll give it a go when I get home.

[Colin Law]

Hopefully you mean javascript lessons. Java is not the same (whether
used for scripting or otherwise). If you are in a java course you are
on the wrong one :)

Colin

[TridiumControls]

Yes. Js.

Phone added an extra space.