Accessing a JSON object based on one key-value

Question

I have incoming json objects. What i want to do is to filter the JSON based on its key. For example I have three incoming json objects.

Sending message: {"deviceId":"test","temperature":11,"latitude":50,"longitude":19,"time":1,"id":398}

Sending message: {"deviceId":"temp","temperature":11,"latitude":50,"longitude":19,"time":1,"id":399}

Sending message: {"deviceId":"temp","temperature":11,"latitude":50,"longitude":19,"time":1,"id":400}

Sending message: {"deviceId":"test","temperature":11,"latitude":50,"longitude":19,"time":1,"id":01}

Sending message: {"deviceId":"temp","temperature":11,"latitude":50,"longitude":19,"time":1,"id":402}

I want only those json objects where deviceid is test and not temp. I am trying to filter the JSON. How can i do this?

is it coming in form of array of objects? if not push those object in ana array and then filter in array using arry filter prototype — Rahul Singh
– Rahul Singh, Commented Aug 11, 2017 at 5:40
parse the JSON strings to javascript objects first ... then use the javascript object like any other i.e. check for obj.deviceId == 'test' - in this case, the JSON string was parsed to an object called obj — Jaromanda X
– Jaromanda X, Commented Aug 11, 2017 at 5:41
What code have you tried so far? The method of filtering will be different depending on how the json is coming in to the script. — wmorrell
– wmorrell, Commented Aug 11, 2017 at 5:41
@JaromandaX Yes, now after i apply this condition, how do i return or print the whole json object based on that value 'test' ? — Neo
– Neo, Commented Aug 11, 2017 at 5:43

forJ · Accepted Answer · 2017-08-11 05:47:21Z

1

I'll write you an example

say you have list of

let obj = {
    "deviceId":"test",
    "temperature":11,
    "latitude":50,
    "longitude":19,
    "time":1,
    "id":398
}

Then you can selecte deviceId by obj['deviceId']

for (let index in listOfObj){

    let curObj = listOfObj[index];

    if(curObj['deviceId'] === 'test'){
        //Do whatever you want with the object
    }
}

answered Aug 11, 2017 at 5:47

forJ

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Comments

Aayushi · Accepted Answer · 2017-08-11 07:07:00Z

1

This is a basic example which describes how you can check whether the deviceId is 'test' or 'temp' and based on that you can run a loop on the object keys and apply whatever logic you want to apply on it.

Hope this helps.

document.addEventListener("DOMContentLoaded",function(e){
var obj = {
    "deviceId":"test",
    "temperature":11,
    "latitude":50,
    "longitude":19,
    "time":1,
    "id":398
}
if(obj["deviceId"]==="test"){
Object.keys(obj).forEach(function(e){
  alert(e+" "+obj[e]);
})
}
})

answered Aug 11, 2017 at 7:07

Aayushi

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Comments

iKoala · Accepted Answer · 2017-08-11 05:43:57Z

0

I suggest you to use Lodash library.

var messages = [{msg1}, {msg2}];
var filteredMessages = _.filter(messages, {deviceId: "test"});
// filteredMessages is an Array of messages with deviceId equals to `test`

answered Aug 11, 2017 at 5:43

iKoala

8804 silver badges11 bronze badges

3 Comments

Jaromanda X Over a year ago

why use a library when native javascript Array's already have a filter method

iKoala Over a year ago

it's because Lodash(or Underscore) is very useful to manipulate data objects in javascript, especially for new learners

coagmano Over a year ago

native javascript is also very useful to manipulate data objects in javascript, ESPECIALLY for new learners

ksami · Accepted Answer · 2017-08-11 06:19:05Z

Assuming your objects are in an array, you can achieve this using the native Javascript Array#filter method,

var arr = [
    {"deviceId":"test","temperature":11,"latitude":50,"longitude":19,"time":1,"id":398},
    {"deviceId":"temp","temperature":11,"latitude":50,"longitude":19,"time":1,"id":399},
    {"deviceId":"temp","temperature":11,"latitude":50,"longitude":19,"time":1,"id":400},
    {"deviceId":"test","temperature":11,"latitude":50,"longitude":19,"time":1,"id":01},
    {"deviceId":"temp","temperature":11,"latitude":50,"longitude":19,"time":1,"id":402}
];

var results = arr.filter(function(obj) {
    // Return true to keep the element
    return obj.deviceId === "test";
});

console.log(results);

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