# Undefs don't want to go away
**URL:** https://discourse.nodered.org/t/undefs-dont-want-to-go-away/68541
**Category:** General
**Created:** [4 October 2022 11:22 UTC](https://discourse.nodered.org/t/undefs-dont-want-to-go-away/68541 "2022-10-04T11:22:25Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@SeRiusRod](https://discourse.nodered.org/u/SeRiusRod)
#### Post date: [4 October 2022 11:22 UTC](https://discourse.nodered.org/t/undefs-dont-want-to-go-away/68541/1 "2022-10-04T11:22:25Z")
I have an strange problem and I thought I could share it in case someone wants to burn some neurons.
I have I flow section where I retrieve data from three modbus queries and build an unique message. For that I use a join node. In the end this json I build with the data is published to mqtt and stored in context.
The modbus is not so stable, so sometimes one part is missing and I get undefined values. So I inserted that function node:
```javascript
if (!msg.payload.hasOwnProperty("power") || msg.payload.power == undefined) {
msg.payload.power = global.get("pv_sources.charger.power") || 0;
node.warn("Warning: Power undefined!");
}
if (!msg.payload.hasOwnProperty("voltage") || msg.payload.voltage == undefined)
msg.payload.voltage = global.get("pv_sources.charger.voltage") || 0;
if (!msg.payload.hasOwnProperty("energy_kwh") || msg.payload.energy_kwh == undefined)
msg.payload.energy_kwh = global.get("pv_sources.charger.energy_kwh") || 0;
if (!msg.payload.hasOwnProperty("energy_daily_kwh") || msg.payload.energy_daily_kwh == undefined)
msg.payload.energy_daily_kwh = global.get("pv_sources.charger.energy_daily_kwh") || 0;
return msg;
```
The debug node sometimes registers the undefined value but the next line shows that is corrected.
After that, the whole payload is stored con context and sent to mqtt.
Now comes the strange thing... The mqtt broker is showing messages without those values that are fixed on the function.
Or
Strange, isn't it?
PS: Buffer nodes reply power, current / voltage / energy\_kwh, energy\_daily\_kwh
Mppt node has a jsonata line that builds the object shown in the context image, and then there's a node that sends it mqtt. No more data changes.
---
### Author:  [@Steve-Mcl](https://discourse.nodered.org/u/Steve-Mcl)
#### Post date: [4 October 2022 12:26 UTC](https://discourse.nodered.org/t/undefs-dont-want-to-go-away/68541/2 "2022-10-04T12:26:48Z")
> [@SeRiusRod](#):
>
> Mppt node has a jsonata line that builds the object shown in the context image, and then there's a node that sends it mqtt. No more data changes.
Since your Undefs function fills out any missing properties, it can only be something to do with either...
- `msg.payload.energy_daily_kwh` is an empty string, 0, false or something else != `undefined`
- i.e. the `if(msg.payload.energy_daily_kwh == undefined)` fails and `msg.payload.energy_daily_kwh = global.get("pv_sources.charger.energy_daily_kwh") || 0;` is not being called.
- you can use a function to better determine this (SEE BELOW)
- the node named `mppt` is doing something odd
- there is a set by reference issue somewhere
- these are solved by deep cloning the msg to ensure it cannot be changed by reference in another node.
* * *
Better test...
As alluded to before, `0`, `''` and `false` will fail to call your `global.get()` ...
You could change it to ...
```auto
if (!isNumeric(msg.payload.power))
msg.payload.power = global.get("pv_sources.charger.power") || 0;
if (!isNumeric(msg.payload.voltage))
msg.payload.voltage = global.get("pv_sources.charger.voltage") || 0;
if (!isNumeric(msg.payload.energy_kwh))
msg.payload.energy_kwh = global.get("pv_sources.charger.energy_kwh") || 0;
if (!isNumeric(msg.payload.energy_daily_kwh))
msg.payload.energy_daily_kwh = global.get("pv_sources.charger.energy_daily_kwh") || 0;
function isNumeric(n) {
return !isNaN(parseFloat(n)) && isFinite(n);
}
return msg;
```
---
### Author:  [@system](https://discourse.nodered.org/u/system)
#### Post date: [3 December 2022 12:27 UTC](https://discourse.nodered.org/t/undefs-dont-want-to-go-away/68541/3 "2022-12-03T12:27:23Z")
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