Data from influxdb to a multiline chart

General
, ,
1

I am trying to get data from influxdb to a multiline chart. I found many examples and tried them. But I don't seem to get it just right. My problem is with the (curly) brackets. Hope anyone can help me solve the problem.

> // Format the InfluxDB results to match the charts JSON format
> var series = ["A", "B"];
> var labels = [""];
> var data = "[[";
> var thetime, selfuse, totalsolar;
>  
> for (var i=0; i < msg.payload.length; i++) {
>     thetime = Number(msg.payload[i].time); // Some manipulation of the time may be required
>     selfuse = msg.payload[i].selfuse;
>     totalsolar = msg.payload[i].totalsolar;
>     data += ' {"x":' + thetime + ', "y":' + selfuse +   '},';      
>     data += ' {"x":' + thetime + ', "y":' + totalsolar +'} ';
>     if (i < (msg.payload.length - 1)) {
>         data += ","
>     } else {
>         data += "]]"
>     }
> }
> 
> var jsondata = JSON.parse(data);
> msg.payload = [{"series": series, "data": jsondata, "labels": labels}];
> 
> return msg;
2

Don't build the data as a string and then convert it to an object, build it as a javascript object, it is much simpler.

3

To clarify a bit, start with declaring data to be an empty array
let data = []
(nowadays you should be using let not var)
Then in the loop create push each item into the array, something like
data.push({x: thetime, y: selfuse})
then at the end, in the payload use data: [data]
Another problem I now see with the code is that you are trying to create two series, so, I think, but I haven't checked the docs, you will need to create arrays dataA and dataB and then in the payload returned use data:[dataA,dataB]

4

Colin, thanks for your reaction, Indeed I am trying for a multi line chart. I have tried to convert this (working) example for a single line chart, but got stuck. Now it is only 2 line chart, but I want even more lines.

5

Does not the method I suggested work? Your original method, even if it works, is not a good way to do it.

6

Yes, I think You are right. I will try your suggestion. I will let you know the result. :slightly_smiling_face:

7

Colin, it works like a charme. You were completly right!! Thanks very much. :slightly_smiling_face:
This is the working function node now.

// Format the InfluxDB results to match the charts JSON format
let series = ["Eigen gebruik","Totaal Opgewekt"];
let labels = ["Watt"];
let data0 = [];
let data1 = [];

for (var i=0; i < msg.payload.length; i++) {
    let thetime = Number(msg.payload[i].time);
    let selfuse = msg.payload[i].selfuse;
    let totalsolar = msg.payload[i].totalsolar;

    data0.push({x: thetime, y: selfuse});     
    data1.push({x: thetime, y: totalsolar});     
}

let data = [data0,data1];

// node.warn(data);

msg.payload = [{"series": series, "data": data, "labels": labels}];

return msg;
1 Like
8

Excellent. Glad to be of help.

9

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