TypeError: Cannot read properties of undefined (reading 'Total_in')"

[Tobi31]

Hi together,

i am trying to extract my mqtt data by a change as well as a function the value Power.Total_in.

This is extracted cleanly, at least according to the debug. Strangely, right after the change in the function comes the following error:

9.9.2023, 21:18:18node: function 1
function : (error) "TypeError: Cannot read properties of undefined (reading 'Total_in')"

Below is the configuration of the change:

and the function:

Does anyone have a solution for this?

Regards,
Tobias

[dceejay]

The change node is setting the payload (and wiping out the Power_In property so when it gets to the function it’s no longer there as it’s now just in the payload

[Tobi31]

That worked perfectly. Thanks for the fast response. But now my functions not working properly.

I will explain my goal first:

I want to grab the meter reading I receive in the morning and write that value to the database. Then the values should be updated, but a difference should always be calculated to calculate the daily consumption of electricity.

I have developed the following 3 scripts to achieve this.

Script 1:

// Greifen Sie auf msg.payload zu, um den Wert zu extrahieren

var currentCounter = parseFloat(msg.payload);

msg.currentCounter = currentCounter;

return msg;

Script 2:

var currentDate = new Date().toISOString().split('T')[0]; // Das aktuelle Datum ohne Uhrzeit extrahieren

// Überprüfen Sie, ob bereits ein erster Zählerstand für heute im Kontext gespeichert ist
if (context.get('firstCounter_' + currentDate) === undefined) {
// Wenn nicht, speichern Sie den aktuellen Zählerstand als ersten Zählerstand des Tages
context.set('firstCounter_' + currentDate, msg.payload);
}
return msg;

Script 3:

// Greifen Sie auf msg.payload zu, um den Wert zu extrahieren

var currentCounter = parseFloat(msg.payload);

// Speichern Sie den aktuellen Zählerstand in einer Flussvariable (flow context)

var previousCounter = flow.get("previousCounter") || 0;

// Berechnen Sie den Tagesverbrauch

var dailyConsumption = currentCounter - previousCounter;

// Speichern Sie den aktuellen Zählerstand als vorherigen Zählerstand für die nächste Berechnung

flow.set("previousCounter", currentCounter);

// Fügen Sie den Tagesverbrauch zur Nachricht hinzu, wenn gewünscht

msg.dailyConsumption = dailyConsumption;

return msg;

Unfortunately, my plan doesn't seem to be that easy to implement or I think just too hard.

Can you help me here as well? I'm an absolute beginner with NodeRed (since 2 days in use) because I wanted to try to make my PV yield or power consumption visible by means of Grafana.

Regards,
Tobias

[smcgann99]

It would be much easier to debug if you post the actual flow here -

In order to make code readable and usable it is necessary to surround your code with three backticks (also known as a left quote or backquote ```)

``` 
   code goes here 
```

See this post for more details - How to share code or flow json