Decoding and parsing JSON using NewtonSoft

So you are working with JSON, you get a JSON message and you want to retrieve some values from it. How?

Let’s suppose you get something like (this is an example take from here):

"{\"port\":1,\"counter\":39,\"payload_raw\":\"KAA=\",\"payload_fields\":{\"errorCode\":0,\"numberOfCycles\":40},\"metadata\":{\"time\":\"2017-01-15T22:55:04.204820257Z\",\"frequency\":868.1,\"modulation\":\"LORA\",\"data_rate\":\"SF7BW125\",\"coding_rate\":\"4/5\",\"gateways\":[{\"gtw_id\":\"eui-b827ebffffc19ca8\",\"timestamp\":4113032806,\"time\":\"1754-08-30T22:43:41.128654848Z\",\"channel\":0,\"rssi\":-90,\"snr\":8,\"latitude\":51.46018,\"longitude\":5.61902,\"altitude\":10}]}}"

The backslashes, the escape characters, are only for C# to know which double quotes are part of the message. It’s not necessary but you can remove them and then you have:

{"port":1,"counter":39,"payload_raw":"KAA=","payload_fields":{"errorCode":0,"numberOfCycles":40},"metadata":{"time":"2017-01-15T22:55:04.204820257Z","frequency":868.1,"modulation":"LORA","data_rate":"SF7BW125","coding_rate":"4/5","gateways":[{"gtw_id":"eui-b827ebffffc19ca8","timestamp":4113032806,"time":"1754-08-30T22:43:41.128654848Z","channel":0,"rssi":-90,"snr":8,"latitude":51.46018,"longitude":5.61902,"altitude":10}]}}

Well, it’s always good to check the message is proper JSON. You can check it with a ‘tool’ like http://jsonlint.com/

This is a valid message, if we format the structure, it looks a lot better:

{
  "port": 1,
  "counter": 504,
  "payload_raw": "+QA=",
  "payload_fields": {
    "errorCode": 0,
    "numberOfCycles": 249
  },
  "metadata": {
    "time": "2017-01-10T23:31:06.087189682Z",
    "frequency": 868.1,
    "modulation": "LORA",
    "data_rate": "SF7BW125",
    "coding_rate": "4/5",
    "gateways": [{
      "gtw_id": "eui-b827ebffffc19ca8",
      "gtw_trusted": true,
      "timestamp": 3771642998,
      "time": "1754-08-30T22:43:41.128654848Z",
      "channel": 0,
      "rssi": -80,
      "snr": 9,
      "latitude": 51.46018,
      "longitude": 5.61902,
      "altitude": 10}]
  }
}

There are several ways to get values from this JSON message.

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