extracting parameter from JSON

Question

I have this JSON:

{"id":"162","name":"Xiaomi Temperature Humidity Sensor","label":"Fridge Temperature","attributes":[{"name":"battery","currentValue":23,"dataType":"NUMBER"},{"name":"batteryLastReplaced","currentValue":"Jun 19 2019","dataType":"STRING"},{"name":"humidity","currentValue":39.2,"dataType":"NUMBER"},{"name":"lastCheckinEpoch","currentValue":null,"dataType":"STRING"},{"name":"lastCheckinTime","currentValue":null,"dataType":"DATE"},{"name":"pressure","currentValue":100.14,"dataType":"NUMBER"},{"name":"temperature","currentValue":3.02,"dataType":"NUMBER"}],"capabilities":["TemperatureMeasurement",{"attributes":[{"name":"temperature","dataType":null}]},"RelativeHumidityMeasurement",{"attributes":[{"name":"humidity","dataType":null}]},"Battery",{"attributes":[{"name":"battery","dataType":null}]},"Sensor","PressureMeasurement",{"attributes":[{"name":"pressure","dataType":null}]}],"commands":["resetBatteryReplacedDate"]}

I'm trying to extract the temperature (3.02), pressure (100.14) and humidity (39.2). Because it's nested (if I understand correctly?) I'm trying some recursive code I found. But I'm really lost to understand how to extract the data I need.

Here is what I have so far:

function updateTPH(deviceId, index, array) {
    
    var responseString = '';
    var xhttp = new XMLHttpRequest();
    xhttp.onreadystatechange = function() {
        if (this.readyState == 4 && this.status == 200) {
            responseString = xhttp.responseText;
            alert(responseString);
            
            var element = document.getElementById(deviceId);            
            
            // Converting JSON object to JS object
            var obj = JSON.parse(json);
            
            // Define recursive function to print nested values
            function printValues(obj) {
                for(var k in obj) {
                    if(obj[k] instanceof Object) {
                        printValues(obj[k]);
                        } else {
                        document.write(obj[k] + "<br>");
                    };
                }
            };
            
            // Printing all the values from the resulting object
            printValues(obj);
            
        }
            
    };
        
    xhttp.open("GET", "http://192.168.0.167/apps/api/" + myMakerAPI + "/devices/" + deviceId + "?access_token=" + myAccessToken, true);
    xhttp.send();
    
};

I'm getting the parameters printed to the page ok, but I cant work out how to isolate the parameters I want into variables I can then use. Any assistance would be much appreciated!

Answer 1

Yes the values are "nested". If you want to access humidity for example you would do something like this: obj["attributes"][2]["currentValue"], because the humidity value is inside the third element of "attributes".

Humidity:

obj["attributes"][2]["currentValue"];

Pressure:

obj["attributes"][5]["currentValue"];

Temperature:

obj["attributes"][6]["currentValue"];

You can assign those values to a variable like so:

var temperature = obj["attributes"][6]["currentValue"];

Answer 2

You can access the inner attributes with the index like below

myObj["attributes"][2]["currentValue"];

Otherwise, you can use below code to generate a JSON object like below and use myObj["temperature"]

{
  "battery": 23,
  "batteryLastReplaced": "Jun 19 2019",
  "humidity": 39.2,
  "lastCheckinEpoch": null,
  "lastCheckinTime": null,
  "pressure": 100.14,
  "temperature": 3.02
}

 let myJSON = {"id":"162","name":"Xiaomi Temperature Humidity Sensor","label":"Fridge Temperature","attributes":[{"name":"battery","currentValue":23,"dataType":"NUMBER"},{"name":"batteryLastReplaced","currentValue":"Jun 19 2019","dataType":"STRING"},{"name":"humidity","currentValue":39.2,"dataType":"NUMBER"},{"name":"lastCheckinEpoch","currentValue":null,"dataType":"STRING"},{"name":"lastCheckinTime","currentValue":null,"dataType":"DATE"},{"name":"pressure","currentValue":100.14,"dataType":"NUMBER"},{"name":"temperature","currentValue":3.02,"dataType":"NUMBER"}],"capabilities":["TemperatureMeasurement",{"attributes":[{"name":"temperature","dataType":null}]},"RelativeHumidityMeasurement",{"attributes":[{"name":"humidity","dataType":null}]},"Battery",{"attributes":[{"name":"battery","dataType":null}]},"Sensor","PressureMeasurement",{"attributes":[{"name":"pressure","dataType":null}]}],"commands":["resetBatteryReplacedDate"]}; let myAttributes = myJSON.attributes.reduce((object, item) => { object[item.name] = item.currentValue; return object; }, {}); console.log(myAttributes); console.log(myAttributes.temperature);

Answer 3

There no need for recursive calls. Your datatype is already predefined, so you can just loop through it.

 const obj = { id: "162", name: "Xiaomi Temperature Humidity Sensor", label: "Fridge Temperature", attributes: [ { name: "battery", currentValue: 23, dataType: "NUMBER" }, { name: "batteryLastReplaced", currentValue: "Jun 19 2019", dataType: "STRING", }, { name: "humidity", currentValue: 39.2, dataType: "NUMBER" }, { name: "lastCheckinEpoch", currentValue: null, dataType: "STRING" }, { name: "lastCheckinTime", currentValue: null, dataType: "DATE" }, { name: "pressure", currentValue: 100.14, dataType: "NUMBER" }, { name: "temperature", currentValue: 3.02, dataType: "NUMBER" }, ], capabilities: [ "TemperatureMeasurement", { attributes: [{ name: "temperature", dataType: null }] }, "RelativeHumidityMeasurement", { attributes: [{ name: "humidity", dataType: null }] }, "Battery", { attributes: [{ name: "battery", dataType: null }] }, "Sensor", "PressureMeasurement", { attributes: [{ name: "pressure", dataType: null }] }, ], commands: ["resetBatteryReplacedDate"], }; function printValues(obj) { const { attributes } = obj; attributes.forEach(({ name, currentValue }) => { if (name === "temperature" || name === "pressure" || name === "humidity") console.log(name, ":", currentValue); }); } printValues(obj)

Answer 4

 var array = new Array(); var obj = JSON.parse(`{"id":"162","name":"Xiaomi Temperature Humidity Sensor","label":"Fridge Temperature","attributes":[{"name":"battery","currentValue":23,"dataType":"NUMBER"},{"name":"batteryLastReplaced","currentValue":"Jun 19 2019","dataType":"STRING"},{"name":"humidity","currentValue":39.2,"dataType":"NUMBER"},{"name":"lastCheckinEpoch","currentValue":null,"dataType":"STRING"},{"name":"lastCheckinTime","currentValue":null,"dataType":"DATE"},{"name":"pressure","currentValue":100.14,"dataType":"NUMBER"},{"name":"temperature","currentValue":3.02,"dataType":"NUMBER"}],"capabilities":["TemperatureMeasurement",{"attributes":[{"name":"temperature","dataType":null}]},"RelativeHumidityMeasurement",{"attributes":[{"name":"humidity","dataType":null}]},"Battery",{"attributes":[{"name":"battery","dataType":null}]},"Sensor","PressureMeasurement",{"attributes":[{"name":"pressure","dataType":null}]}],"commands":["resetBatteryReplacedDate"]}`); function printValues(obj) { for (var k in obj) { if (obj[k] instanceof Object) { printValues(obj[k]); } else if (obj[k] == 'temperature' || obj[k] == 'humidity' || obj[k] == 'pressure') { if (obj['currentValue'].== undefined) array;push(obj[k] + " " + obj['currentValue']) } } }; // Printing all the values from the resulting object printValues(obj). console;log(array);

Although already answered by other community members, I would also like to share my solution