How to extract key names from JSON Payload in WSO2 Enterprise Integrator

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I'm using WSO2 EI to ingest data from the Things Network via webhooks.

The core payload format comes in something like this :

{"frm_payload": "AQDPAkMEAAAFBQcOPg==",
      "decoded_payload": {
        "humidity": 67,
        "light": 0,
        "motion": 5,
        "temperature": 20.7,
        "vdd": 3646
      }

what I want to be able to do is transform/pivot that into an array of pairs of names and values for ingesting into my SQL database, e.g.:

{
    "Sensors": [{
            "SensorName": "humidity",
            "SensorData": 67
        },
        {
            "SensorName": "light",
            "SensorData": 0
        },
        {
            "SensorName": "motion",
            "SensorData": 5
        },
        {
            "SensorName": "temperature",
            "SensorData": 20.7
        }, {
            "SensorName": "vdd",
            "SensorData": 3646
        }
    ]
}

However I won't necessarily know the key names for for the incoming JSON pairs . E.g. If I add a new sensor that is going to start reporting 'distance' I don't want to have to modify my mediators to look specifically for 'distance' in the payload , but take that key name and use it as a value for 'SensorName'

wso2-enterprise-integrator wso2-api-manager pivot json
1 Answers

I think, for your case the easiest way is to use ScriptMediator like below:

<script language="js">
<![CDATA[
   var message = mc.getPayloadJSON();
   var decoded_payload = message.decoded_payload;
   var sensorsArr = [];
   for (var keyval in decoded_payload){
      sensorsArr.push({"SensorName": keyval, "SensorData": decoded_payload[keyval] });
   }
   var payload = {"Sensors": sensorsArr};                        
   mc.setPayloadJSON(payload);]]>
</script>

As the output you will get exactly what you looking for.

user_27605060
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