Declaring array of objects in payload

Hello. I'm trying to declare an array of objects into my msg.payload using a JavaScript node.
I declare my array as such:

        msg.payload = {
            DeviceID :  '0',
            Sensors :  []

And the Sensors array is suposed to contain objects that look like this:

     SensorID : 'NULL',
     Value : 0

However, I'm having trouble inserting a new instance of an object into Sensors. For example: If I try to insert a value after the array declaration, ex: msg.payload.Sensors[index].Value = myValue, I get an error telling me that the array Sensors is undeclared, and that I can't set it's value.
How would i go about declaring the Sensors array properly in order to insert new values at a given index?

I don't think you can assign values to payload.Sensors[n] until that array element exists.
You need to push the object onto the array.

msg.payload = {
    DeviceID: '0',
    Sensors: []
const obj = {"SensorID": 42, "Value": 98}
1 Like

Or you would have to declare the Sensors index as an object first.

msg.payload.Sensors[index] = {}; // make sure outside loop or will over write index value.
msg.payload.Sensors[index].value = 0;


msg.payload.Sensors[index] = {SensorID: null, Value: 0};

Thank you. This worked for me.

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