javascript - Json - Node-RED Extract -

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noob looking help...

i have json stream of data looks this.. 

{   "header" : {     "content" : "telegram",     "gateway" : "en-gw",     "timestamp" : "2016-08-08t13:45:47.032+0100"   },   "telegram" : {     "deviceid" : "01864892",     "friendlyid" : "boardroom-co2-sensor",     "timestamp" : "2016-08-08t13:45:47.032+0100",     "direction" : "from",     "functions" : [ {       "key" : "humidity",       "value" : 39.00,       "unit" : "%"     }, {       "key" : "concentration",       "value" : 830.00,       "unit" : "ppm"     } ],     "telegraminfo" : {       "data" : "4e53820e",       "status" : "0",       "dbm" : -67,       "rorg" : "a5"     }   } }

from in node-red have function node looks this...

return [msg.payload.telegram.functions];

which returns these

{ "key": "concentration", "value": 830, "unit": "ppm", "_msgid": "ff5b0f47.00a4f" }  { "key": "humidity", "value": 39, "unit": "%", "_msgid": "ff5b0f47.00a4f" }  { "key": "temperature", "value": 26.6, "unit": "°c", "_msgid": "ef2d6de7.10d29" }

from these single value each e.g. 830 concentration. have check against thresholds set me in node 2 outputs. example if more 1000 output 1, less 1000 output 2.

is i'm trying achieve possible in node-red??

sorry possible noob question appreciated.

the problem not returning formatted message object. while returning function json object not conforming node-red convention.

anything return function node should have payload field if want other nodes able handle easily.

so if change return this:

return { payload: msg.payload.telegram.functions }

then downstream nodes know in msg.payload useful content of message.

as comparing keys within message set values , outputting different values that's relatively simple. in new function node this:

//check concentration exists (var i=0;i<msg.payload.length; i++) {     if (msg.payload[i].concentration) {        //more 1000        if (msg.payload.conentration >= 1000) {            return {payload: 1};        //less 1000        } else {            return {payload: 0};        }     } }

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