I need help with the code from a function node

General
1

So I tried programming a function node which builds the average of the last 5 sent values and then sends it away.(to a database, because of that I save the first timestamp)
But it just wont send away anything. Did I use the context wrong? I dont know what my mistake is.
Here is the code:

var data = context.get(['count','time','spannung','strom'])||0;

var count = data[0];
var time=data[1];
var spannung=data[2];
var strom=data[3];

count+=1;
spannung += msg.payload.Spannung;
strom += msg.payload.Strom;
    
if(time==0){
    time= Date.now();
}

if(count==5){

    spannung = spannung/5;
    strom = strom/5;

    msg.payload = [{
        Spannung: spannung,
        Strom: strom,
        time: time
    },
    {
        Geraet: "WR1"
    }];
    
    context.set(['count','time','spannung','strom'],[0,0,0,0]);
    return msg;
    
} else{
    context.set(['count','time','spannung','strom'],[count,time,spannung,strom]);
    return null;
}

Does anyone of you know what my mistake is?

2

var data = context.get(['count','time','spannung','strom'])||0;
Possibly you shouldnt assign 0 to data if context.get is not truthy but an array || [0,0,0,0]

if(count==5){ better check for if (count >= 5){ just in case

untested

3

Unfortunately this did also not work.

I tried just using context.get and context.set ones for every variable and now it does work!

But I really wonder what I did wrong.

4

You can sprinkle node.warn() statements, showing appropriate data, through your function so you can follow the flow and see what values variables are set to as it goes through.

5

Me too i would make each get set seperate to read it more easily

Try this if it works for you

[{"id":"4b1aa83c30695bb7","type":"function","z":"54efb553244c241f","name":"Average","func":"var count = context.get('count') || 0;\nvar spannung = context.get('spannung') || 0;\nvar strom = context.get('strom') || 0;\n\n// add\ncount += 1;\nspannung += msg.payload.Spannung;\nstrom += msg.payload.Strom;\n\n// set\ncontext.set('count', count);\ncontext.set('spannung', spannung);\ncontext.set('strom', strom);\n\nif (count >= 5) {\n\n    spannung = spannung / 5;\n    strom = strom / 5;\n\n   // prepare msg.payload\n    msg.payload = {\n        Spannung: spannung,\n        Strom: strom,\n        time: Date.now(),\n        Geraet: \"WR1\"\n    }\n\n    //reset\n    context.set('count', 0);\n    context.set('spannung', 0);\n    context.set('strom', 0);\n\n    return msg;\n\n}\n","outputs":1,"noerr":0,"initialize":"","finalize":"","libs":[],"x":680,"y":1000,"wires":[["b4ecf2c64f90cbc4"]]},{"id":"7778c2f4c97316b2","type":"inject","z":"54efb553244c241f","name":"","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"","payloadType":"date","x":220,"y":1000,"wires":[["a678437527317254"]]},{"id":"a678437527317254","type":"function","z":"54efb553244c241f","name":"Random data","func":"msg.payload = {\n    Spannung: Math.random() * 20 + 220,\n    Strom: Math.random() * 10 + 3 \n}\n\nreturn msg;","outputs":1,"noerr":0,"initialize":"","finalize":"","libs":[],"x":400,"y":1000,"wires":[["4b1aa83c30695bb7","9d16310eb6981937"]]},{"id":"9d16310eb6981937","type":"debug","z":"54efb553244c241f","name":"","active":false,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","statusVal":"","statusType":"auto","x":520,"y":920,"wires":[]},{"id":"b4ecf2c64f90cbc4","type":"debug","z":"54efb553244c241f","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","statusVal":"","statusType":"auto","x":860,"y":1000,"wires":[]}]
6

You are creating an array of strings not numbers with your context.get.

Your output results in msg.payload[0].Spannung etc., is this the same as the input? If not, and assuming that you meant the output to be an array.

let [count, time, spannung, strom] = context.get("data") || [0, 0, 0, 0]

count += 1;

spannung += msg.payload.Spannung;
strom += msg.payload.Strom;

if(time == 0){
    time = Date.now();

}

if(count >= 5){
    spannung = spannung/5;
    strom = strom/5;

    msg.payload = [{
        Spannung: spannung,
        Strom: strom,
        time: time

    },

    {
        Geraet: "WR1"

    }];

    context.set('data',[0, 0, 0, 0]);

    return msg;

} else{
    context.set('data',[count, time, spannung, strom]);

    return null;

}
2 Likes
7

Sorry for the late answer, I was busy in the last week.
Thanks that was the mistake, in hindsight it is totally clear why it did not work.
Thanks!

8

This topic was automatically closed 14 days after the last reply. New replies are no longer allowed.