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node-red

modifying a payload containing array of objects

Just trying to learn Node-Red, and struggling with handling messages.

I have a node that queries a mysql database and returns a payload containing an array of objects. payload: enter image description here

I am wanting to pass the values to a dashboard graph node. However I believe I need to pass it an array in the form

payload: array[64]
[0...9]
 [0: 22.2]
   .
   .

etc.

I've tried a function - 

var outmsg = [];
for (var w in msg)
{
   outmsg.push(w.Temperature);
}
return {payload: outmsg, topic: msg.length};

Obviously this is completely the wrong way of doing it... Can anyone help please?

ps. Sorry if this is a duplicate of something answered somewhere else. I did google, but found nothing.

Solution

  • It is best practice to not recreate messages, but to pass on the input message if possible, so the following is better:

    for (var i in msg.payload) {
    msg.payload[i] = msg.payload[i].time
}
return msg;