I am working with Node-RED in Bluemix for IoT.
How can I parse out the individual pieces of information (like the cmdmsg and the tempr) in a function node so I can use it in other nodes in the flow?
I'm getting an error when I try (see below)
I am receiving the JSON complete message object (from an IoT in Node) that I see in my "debug" node when I set it to look at the complete message object. see the object below.
It appears to me that the JSON is formatted correctly.
I tried putting the following in the function node, but I'm getting an error that says "TypeError: Cannot read property 'tempr' of undefined"
Here is what the function parameter is:
return {payload:msg.payload.d.tempr};
and here is the message object
{
"topic": "iot-2/type/Arduino-tempsensor/id/FFFFFFFFFFFF/evt/status/fmt/json",
"payload": "{\n\"d\": {\n\"myName\": \"Arduino CF\",\n\"cmdmsg\": \"Weekly\",\n\"tempr\": -3,\n}\n}",
"deviceId": "FFFFFFFFFFFF",
"deviceType": "Arduino-tempsensor",
"eventType": "status",
"format": "json",
"_msgid": "ffffffff.55555"
}
note: I obfuscated the device ID (mac address) and msgid
Any ideas on how to parse the data out and why I'm getting an error?
Sorry, but your JSON Payload is completely messed up, it should look like this: {"d": {"myName": "Arduino CF","cmdmsg": "Weekly","tempr": -3}}
You shouldn't see any \or \nin the payload, they look like escape characters from the client side. I also believe that the last comma after the tempr value shouldn't be there for valid JSON.
I am not an Arduino expert but I have experimented with a Raspberry Pi and the Mosquitto client, this is how I can successfully send an event to IoTF:
mosquitto_pub -h <org>.messaging.internetofthings.ibmcloud.com -p 1883 -u "use-token-auth" -P "<token>" -i d:<org>:raspi:raspi2 -t iot-2/evt/message/fmt/json -m {"d":{"text":"Hello World"}}
If the paylod is correct JSON your statement return {payload:msg.payload.d.tempr}; will work.
Have you seen this: http://www.ibm.com/developerworks/cloud/library/cl-bluemix-arduino-iot2/
The JSON string you are showing should be converted to a Javascript object before you try to access its fields. To do that is as simple as wiring the arduino output to a "JSON" node, which does the conversion for you (or throws an error if the string is not valid JSON).
Wire the output of the JSON node to a debug node, if you want to see the structure of the msg object. You can also wire it to a "change" node, if you simply want to replace the msg.payload with the temperature value, for instance. You don't need any custom javascript code in a function node to do simple changes like that.
Here is a sample flow that you can import... the arduino output string is simulated by pasting your payload into a "template" node:
[{"id":"1a79abfe.b8abb4","type":"inject","z":"58c8eb7a.5496c4","name":"send output","topic":"iot-2/type/Arduino-tempsensor/id/FFFFFFFFFFFF/evt/status/fmt/json","payload":"true","payloadType":"bool","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":170,"y":2740,"wires":[["9fc678fb.ae18e8"]]},{"id":"69e91778.e0c6e8","type":"json","z":"58c8eb7a.5496c4","name":"","property":"payload","action":"","pretty":false,"x":390,"y":2800,"wires":[["d066800f.60a9b","cf991eb1.f2a1a"]]},{"id":"9d8d7da2.2a7da","type":"debug","z":"58c8eb7a.5496c4","name":"msg string","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"payload","x":610,"y":2740,"wires":[]},{"id":"9fc678fb.ae18e8","type":"template","z":"58c8eb7a.5496c4","name":"arduino string","field":"payload","fieldType":"msg","format":"json","syntax":"plain","template":"{\n \"d\": {\n \"myName\": \"Arduino CF\",\n \"cmdmsg\": \"Weekly\",\n \"tempr\": -3\n }\n}","output":"str","x":360,"y":2740,"wires":[["69e91778.e0c6e8","9d8d7da2.2a7da"]]},{"id":"d066800f.60a9b","type":"change","z":"58c8eb7a.5496c4","name":"extract tempr","rules":[{"t":"set","p":"payload","pt":"msg","to":"payload.d.tempr","tot":"msg"}],"action":"","property":"","from":"","to":"","reg":false,"x":450,"y":2860,"wires":[["af730d72.2995a"]]},{"id":"af730d72.2995a","type":"debug","z":"58c8eb7a.5496c4","name":"tempr","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"true","x":630,"y":2860,"wires":[]},{"id":"cf991eb1.f2a1a","type":"debug","z":"58c8eb7a.5496c4","name":"msg object","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"payload","x":610,"y":2800,"wires":[]}]
As was noted, your original JSON string was not valid, because of the trailing comma -- but it is ok to have double-quotes and newlines as long as they are escaped with a "\". When the string is parsed, they are stripped out anyway.
