# Export MQTT message to InfluxDB
**URL:** https://discourse.nodered.org/t/export-mqtt-message-to-influxdb/45105
**Category:** General
**Created:** [3 May 2021 11:50 UTC](https://discourse.nodered.org/t/export-mqtt-message-to-influxdb/45105 "2021-05-03T11:50:00Z")
**Posts on this page:** 8
**Page:** 1
### Author:  [@TimTist](https://discourse.nodered.org/u/TimTist)
#### Post date: [3 May 2021 11:50 UTC](https://discourse.nodered.org/t/export-mqtt-message-to-influxdb/45105/1 "2021-05-03T11:50:00Z")
Via a sensor connected to TTN LoRa I receive an MQTT message with the measured temperature and humidity:
_payload.uplink\_message.decoded\_payload.TempC\_SHT_
_payload.uplink\_message.decoded\_payload.Hum\_SHT_
My intention is to store the measurements in an Influx Database and therefore I first have to convert the above info to something like:
_temp: 23.0_
_humi: 43.9_
I have tried to do that with a Function Node but I did not succeed, probably because of my lack of knowledge. Can someone tell me the correct code to enter in that node?
```auto
[{"id":"7975535b.a29c1c","type":"tab","label":"Test LHT65","disabled":false,"info":""},{"id":"ab44a611.e93c38","type":"mqtt in","z":"7975535b.a29c1c","name":"MQTT #","topic":"#","qos":"2","datatype":"json","broker":"c1daf86e.852c98","x":240,"y":380,"wires":[["8f9758ff.9fad18","c499e849.b56128"]]},{"id":"8f9758ff.9fad18","type":"debug","z":"7975535b.a29c1c","name":"Temp","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"payload.uplink_message.decoded_payload.TempC_SHT","targetType":"msg","x":510,"y":260,"wires":[]},{"id":"c1840ce.1ae62f","type":"influxdb out","z":"7975535b.a29c1c","influxdb":"30c360.5b7f3ca","name":"DB Lucht","measurement":"","precision":"","retentionPolicy":"","x":700,"y":420,"wires":[]},{"id":"fa76fbf5.821468","type":"function","z":"7975535b.a29c1c","name":"","func":"\nreturn msg;","outputs":1,"noerr":0,"x":510,"y":420,"wires":[["c1840ce.1ae62f"]]},{"id":"c499e849.b56128","type":"debug","z":"7975535b.a29c1c","name":"Humi","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"payload.uplink_message.decoded_payload.Hum_SHT","targetType":"msg","x":510,"y":320,"wires":[]},{"id":"c1daf86e.852c98","type":"mqtt-broker","z":"","name":"Kanweg","broker":"eu1.cloud.thethings.network","port":"1883","clientid":"","usetls":false,"compatmode":false,"keepalive":"60","cleansession":true,"birthTopic":"","birthQos":"0","birthPayload":"","closeTopic":"","closeQos":"0","closePayload":"","willTopic":"","willQos":"0","willPayload":""},{"id":"30c360.5b7f3ca","type":"influxdb","z":"","hostname":"192.168.2.185","port":"8086","protocol":"http","database":"lucht","name":"DB Lucht","usetls":false,"tls":""}]
```
---
### Author:  [@ghayne](https://discourse.nodered.org/u/ghayne)
#### Post date: [3 May 2021 12:08 UTC](https://discourse.nodered.org/t/export-mqtt-message-to-influxdb/45105/2 "2021-05-03T12:08:42Z")
You can do this in a change node:
```auto
[{"id":"bf52dfea.c0cf5","type":"change","z":"b8546237.5f9b8","name":"","rules":[{"t":"set","p":"payload","pt":"msg","to":"{\t\"temp\": payload.uplink_message.decoded_payload.TempC_SHT,\t\"humi\":payload.uplink_message.decoded_payload.Hum_SHT\t}","tot":"jsonata"}],"action":"","property":"","from":"","to":"","reg":false,"x":270,"y":380,"wires":[[]]}]
```
---
### Author:  [@TimTist](https://discourse.nodered.org/u/TimTist)
#### Post date: [3 May 2021 12:53 UTC](https://discourse.nodered.org/t/export-mqtt-message-to-influxdb/45105/3 "2021-05-03T12:53:00Z")
Very nice to help me, it works perfectly. When I look at the code like this it seems simple, but for me it was nevertheless a difficult puzzle.
Thanks!
---
### Author:  [@TotallyInformation](https://discourse.nodered.org/u/TotallyInformation)
#### Post date: [3 May 2021 14:12 UTC](https://discourse.nodered.org/t/export-mqtt-message-to-influxdb/45105/4 "2021-05-03T14:12:23Z")
In my own flows, I have a standard output to InfluxDB flow. This has a link-in node and I send to it from anywhere I need to save data. It (re)formats incoming data to the correct output format. and sends it to InfluxDB.
---
### Author:  [@TimTist](https://discourse.nodered.org/u/TimTist)
#### Post date: [3 May 2021 15:01 UTC](https://discourse.nodered.org/t/export-mqtt-message-to-influxdb/45105/5 "2021-05-03T15:01:47Z")
Thanks, appreciated!
---
### Author:  [@jaeti01](https://discourse.nodered.org/u/jaeti01)
#### Post date: [4 May 2021 13:16 UTC](https://discourse.nodered.org/t/export-mqtt-message-to-influxdb/45105/6 "2021-05-04T13:16:11Z")
Can you possibly share the flows behind these screenshots? I think its a great example.
thanks!
---
### Author:  [@TotallyInformation](https://discourse.nodered.org/u/TotallyInformation)
#### Post date: [4 May 2021 13:35 UTC](https://discourse.nodered.org/t/export-mqtt-message-to-influxdb/45105/7 "2021-05-04T13:35:39Z")
Obviously this is rather specific to the way I have things set up and how I configure InfluxDB. I've shared the configuration of my environment db previously.
Validate Input fn:
```auto
/**
* Validate input suitable for the influxdb-out node.
* We will ALWAYS use the "array containing two objects" payload
* OR the singe Object payload (if no tags being used).
* See the Description tab for more details.
*/
// check measurement field is set - if not exit with error
if ( ! msg.measurement ) {
node.error('msg.measurement is missing')
node.send([null,msg])
return
}
let fields,tags
// if payload is an object, assume that it contains fieldName:fieldValue pairs
if ( msg.payload!== null && msg.payload.constructor.name === 'Object' ) {
fields = msg.payload
} else if ( msg.payload!== null && msg.payload.constructor.name === 'Array' ) {
node.error('msg.payload cannot be an array. It must be an object containing fieldName:fieldValue pairs or a single value (which would be written to the `value` field name).')
node.send([null,msg])
return
} else {
// Otherwise, we always use 'value' as the default field name
fields = {'value': msg.payload}
}
const lstFields = Object.keys(fields)
// check to make sure that there is a value field name - if not, continue but with a warning
if ( ! lstFields.includes('value') ) {
// Lets us turn off the warning if we know what we are doing :-)
if ( msg.noValueField !== true )
node.warn('Default field name "vaue" not present, was that deliberate? Set msg.noValueField=true or use the `value` field name to avoid this msg')
}
// check to make sure that all field values are numeric - if not, exit with a warning
let allNumeric = true
lstFields.forEach( key => {
// I use On/Off for simple switch values in MQTT but these are not useful
// in InfluxDB, so translate them to ON=1 and OFF=0 (ignoring case).
try {
if ( fields[key].toLowerCase() === 'on' ) fields[key] = 1
if ( fields[key].toLowerCase() === 'off' ) fields[key] = 0
} catch (e) {}
// then check to make sure the field is actually a number
if ( parseFloat(fields[key]) !== fields[key] ) {
node.error(`Field msg.payload.${key} is not numeric. Only use numbers for field values, text should go in tags.`)
allNumeric = false
node.send([null,msg])
return
}
})
if ( allNumeric === false ) {
return
}
// check to make sure that if msg.tags is present, it is an object - if not, exit with a warning
if ( msg.tags ) {
if ( !(msg.tags!== null && msg.tags.constructor.name === 'Object') ) {
node.error('msg.tags is not an object - it must contain tagName:tagValue pairs')
node.send([null,msg])
return
}
tags = msg.tags
}
// Format the output to go to the InfluxDB out node
if ( msg.tags ) {
msg.payload = [
fields,
tags,
]
} else {
msg.payload = fields
}
return msg;
```
Second fn:
```auto
const splitTopic = msg.topic.split('/')
let location = splitTopic[2]
let type = splitTopic[1]
if ( splitTopic[3] === 'switch' ) type = splitTopic[3]
if ( splitTopic[3] === 'temperature_measured' ) type = 'temperature_trv'
if ( splitTopic[2] )
try {
msg.payload = JSON.parse(msg.payload)
} catch (e) {
// node.warn(`Failed to parse incoming MQTT payload. "${msg.topic}", ${e.message}`)
// return
}
msg.measurement = 'environment'
msg.tags = {
'location': location,
'type': type,
}
return msg;
```
---
### Author:  [@system](https://discourse.nodered.org/u/system)
#### Post date: [18 May 2021 13:36 UTC](https://discourse.nodered.org/t/export-mqtt-message-to-influxdb/45105/8 "2021-05-18T13:36:22Z")
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