How to parse JSON with dynamic key value in JavaScript

Question

I have a JSON array with dynamic key value (room number, it will change every time I run the code). I'm wondering how to access inner JSON array with this key value. Here's what I have tried and it throws an error.

JSON Array(data)

[{"6011":
 [{"occupancy":"2","time":"2017-11-10 00:00:00"},
 {"occupancy":"1","time":"2017-11-10 00:30:00"},
 {"occupancy":"2","time":"2017-11-10 01:00:00"}]
}]

Code to access

var room = outerJSON.name;

var jsonObject = jQuery.parseJSON(JSON.stringify(data));

var innerArray = jsonObject[room]; // returns undefined
var innerArray2 = jsonObject.get(room); // Uncaught TypeError: jsonObject.get is not a function

It seems like your Json object is inside an array what does `jsonObject[0][room]` do? — Noel Kriegler, Nov 28 '17 at 15:11
Is `room` `6011`? Since your object is wrapped in an array, you need to `find` that object first: `jsonObject.find(obj => obj.hasOwnProperty(room))`. — Sebastian Simon, Nov 28 '17 at 15:13
Why are you calling `jQuery.parseJSON(JSON.stringify(data))`? What's the point in stringifying it, then parsing it again? — Cerbrus, Nov 28 '17 at 15:17
@Cerbrus That question is about finding objects with a fixed property name. This one is about finding objects by a dynamic key name. — Sebastian Simon, Nov 28 '17 at 15:37
@Xufox: No, this question is just about getting the first entry from an array. The OP just doesn't realize that. — Cerbrus, Nov 28 '17 at 15:40

score 2 · Answer 1 · edited Nov 10 '19 at 20:07

2

Your object are inside an array, so you should point your code to the first column of the array jsonObject using [0] like :

var innerArray = jsonObject[0][room];

var data = [{
  "6011": [{
      "occupancy": "2",
      "time": "2017-11-10 00:00:00"
    },
    {
      "occupancy": "1",
      "time": "2017-11-10 00:30:00"
    },
    {
      "occupancy": "2",
      "time": "2017-11-10 01:00:00"
    }
  ]
}];

var room = "6011";
var jsonObject = jQuery.parseJSON(JSON.stringify(data));
var innerArray = jsonObject[0][room];

console.log(innerArray);

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

edited Nov 10 '19 at 20:07

halfer

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answered Nov 28 '17 at 15:13

Zakaria Acharki

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Why are you using jQuery to parse the json? Or why are you even stringifying it here? – Cerbrus Nov 28 '17 at 15:15
Since the author already using jQuery, why not ? – Zakaria Acharki Nov 28 '17 at 15:16
The problem is in accessing the data. I'd suggest keeping the answer as short as possible. – Cerbrus Nov 28 '17 at 15:17
I'm not sure what you mean, but the answer already has one line ? (The snippet just uses the same code in the OP + [0]) – Zakaria Acharki Nov 28 '17 at 15:18

Sebastian Simon · Answer 2 · 2017-11-28T15:39:59.027

Assuming room has the value 6011 or "6011", and assuming {"6011":…} is not always the only object in the array, you need to find that object first, since your object is wrapped in an array. You can then access the room property by [room].

var jsonObject = [{ "6011": [{ "occupancy": "2", "time": "2017-11-10 00:00:00" }, { "occupancy": "1", "time": "2017-11-10 00:30:00" }, { "occupancy": "2", "time": "2017-11-10 01:00:00" } ] }, { "6012": [{ "occupancy": "2", "time": "2017-11-10 00:00:00" }, { "occupancy": "1", "time": "2017-11-10 00:30:00" }, { "occupancy": "2", "time": "2017-11-10 01:00:00" } ] }],
  room = 6011;

var foundObject = jsonObject.find(obj => obj.hasOwnProperty(room));

console.log(foundObject && foundObject[room]);

.as-console-wrapper { max-height: 100% !important; top: 0; }

How to parse JSON with dynamic key value in JavaScript

2 Answers2