# Failing to write a LoRaWAN gweui into a variable
**URL:** https://discourse.nodered.org/t/failing-to-write-a-lorawan-gweui-into-a-variable/41939
**Category:** General
**Created:** [3 March 2021 10:21 UTC](https://discourse.nodered.org/t/failing-to-write-a-lorawan-gweui-into-a-variable/41939 "2021-03-03T10:21:20Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@manankanchu](https://discourse.nodered.org/u/manankanchu)
#### Post date: [3 March 2021 10:21 UTC](https://discourse.nodered.org/t/failing-to-write-a-lorawan-gweui-into-a-variable/41939/1 "2021-03-03T10:21:21Z")
Hi,
I'm working on a small status monitoring solution for LoRaWAN gateways using metadata of device messages coming in via MQTT.
I'm using [https://groups.google.com/g/node-red/c/bahx8U3oBdI?pli=1](https://groups.google.com/g/node-red/c/bahx8U3oBdI?pli=1) as a basis which works fine for me when I use part of the msg.topic string and put it into a variable like Lennart Hennig:
var parts = msg.topic.split ("/");
generating a payload like
be010004: "online"
where be010004 is the split part of the topic.
But what I need is part of the msg.payload like:
gweui: "FCAAAAAAAAAAAAAA"
status: "online"
being modified to a new payload
FCAAAAAAAAAAAAAA: "online"
When I try to enter the gweui into a variable like
var parts = msg.payload.gweui ;
it fails ... as you already might have guessed I'm not really fit in JS and I think I got (again) somewhat lost in JSON object \<-\> string stuff, but all my attempts to use a JSON converter in Node-RED failed to insufficient know how ...
Any hint welcome !
Matthias
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### Author:  [@manankanchu](https://discourse.nodered.org/u/manankanchu)
#### Post date: [3 March 2021 13:48 UTC](https://discourse.nodered.org/t/failing-to-write-a-lorawan-gweui-into-a-variable/41939/2 "2021-03-03T13:48:16Z")
... well, could solve it with the help of a friend 😉 ...
Obviously I tried to access an element of an array which was no array ... well, lessons learned.
I'm now creating the status directly
deviceStatus[msg.payload.gweui] = (msg.payload.status == "true") ? "online" : "offline";
... sorry for the noise !
Matthias
---
### Author:  [@system](https://discourse.nodered.org/u/system)
#### Post date: [17 March 2021 13:48 UTC](https://discourse.nodered.org/t/failing-to-write-a-lorawan-gweui-into-a-variable/41939/3 "2021-03-17T13:48:59Z")
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