MQTT->(JSON)->?->InfluxDB->Grafana

#1

Hi, I'm brand new to NodeRed, MQTT, InfluxDB and Grafana

I'm trying to visualize Data form a ESP8266. Onto the dashboard the data come in. But I've got an issue to transform the MQTT data into an proper format for InfluxDB. NodeRed time series graphs work fine, but I can't visualize the MQTT sensor data in Grafana.

What should I do? A transformation with the json block, and a custom function. But what shoult the function looks like? Everything I tried doesn't work.

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#2

I prefer to use the influx batch node over the single influxdb node because it works a bit more efficiently for large quantities of data. It likes data to be an array of objects. Here's an example of the format it likes:

var field1Data = 10
var field2Data = 12
var field3Data = 15
var tag1Data = "what is this?"
var tag2Data = "I'm a tag!"

    var payload=(
        {measurement: "measurementName",
            fields: {
                field1: field1Data,
                field2: field2Data,
                field3: field3Data
            },
            tags: {
                tag1: tag1Data,
                tag2: tag2Data
            },
            timestamp: new Date()
        })
    node.send({payload})

You would of course want to grab parts of your inbound message to populate your fields and tags as per your use case. This is set up in a way that you can use a join node at the end of the flow to combine a predetermined number of payloads into an array to send through influx batch.

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#3

If the data is minimal, and you want to use the influx single node, this works for me -

if(msg.node == 18) {
    var temp = (msg[0])/100;
    var batt = (msg[1])/1000;
msg.payload = [{
    temp: temp,
    battery: batt
},
{
    device:"th18"
}];
msg.measurement = "iot";
return msg;
} else {
    return null;
    }


...so, I've got 4 sensors, and the 'if' condition only runs the function if the incoming flow contains msg.node == 18
device:"th18" is the tag
msg.measurement = "iot" is the measurement

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Basic advice needed on parsing JSON
#4

Thanks! Now it's running. I also used the examples of nodeRed itself.

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