Get collection of elements from JSON

Question

I have a JSON file with the structure as below:

{"root" : {
     "parent" : {
          "childA" : 
              ["element1",
               "element2"],
          "childB" :
              ["element1",
               "element2"]
     }
}

How can I get a collection of children [childA, childB] from it?

For now what I'm doing:

Parse the JSON file to an object (I know how to do that and suggested response is about this).

Create the collection:

var collection = [JSON.root.parent.childA, JSON.root.parent.childB];
collection.forEach(function(child) {
    print(child[0])
});

to print "element1".

I'm new to JavaScript but I believe there is a better and more generic way to achieve the point 2.

EDIT: I forgot to add that this Java Script is used inside Nashorn jjs script.

Possible duplicate of [Safely turning a JSON string into an object](https://stackoverflow.com/questions/45015/safely-turning-a-json-string-into-an-object) — clinomaniac, Feb 09 '18 at 17:43
Don't use "JSON" as a variable name, you're at risk to override or shadow the native `window.JSON` object. — Teemu, Feb 09 '18 at 17:53
@clinomaniac - Suggested topic is about parsing JSON string. My question is not about parsing JSON, but rather how to extract particular elements from the JSON object. — blekione, Feb 12 '18 at 08:46

Ankit Agarwal · Accepted Answer · 2018-02-09T17:58:46.480

1

Simply use Object.keys() for this:

var data = {"root" : {
     "parent" : {
          "childA" : 
              ["element1",
               "element2"],
          "childB" :
              ["element1",
               "element2"]
     }
   }
};
var collection = [];
for (var childIndex in data.root.parent){
  data.root.parent[childIndex].every(child => collection.push(child));
};
console.log(collection);

edited Feb 09 '18 at 17:58

answered Feb 09 '18 at 17:46

Ankit Agarwal

30,378
5
37
62

This returns keys only, so for `console.log(child[0]` I have output `childA` not `element1` – blekione Feb 09 '18 at 17:53
This works for me... kind of. I like @Musa answer more, but it doesn't work inside of a jjs script. – blekione Feb 09 '18 at 18:17
"*Simply use Object.keys() for this*" ... ? – Don't Panic Apr 13 '22 at 09:09

Musa · Answer 2 · 2018-02-09T18:18:30.620

1

You can use Object.values to get the entries in the parent object.

var data = {"root" : {
     "parent" : {
          "childA" : 
              ["element1",
               "element2"],
          "childB" :
              ["element1",
               "element2"]
     }
   }
};


var collection = []; 
for (var o in data.root.parent){
    collection.push(data.root.parent[o]);
}
collection.forEach(function(child) {
    console.log(child[0]);
});

edited Feb 09 '18 at 18:18

answered Feb 09 '18 at 17:53

Musa

96,336
17
118
137

I forgot to add that this code is running as jjs Nashorn script and for some reasons it doesn't recognise `Object.values` as a valid function, but your code is actually what I want to achieve. – blekione Feb 09 '18 at 18:14

score 0 · Answer 3 · answered Feb 08 '22 at 06:57

0

You can try using JToken also -

 using Newtonsoft.Json.Linq;    

 JToken.Parse(response.Content)
.SelectTokens("root.parent");

answered Feb 08 '22 at 06:57

Himalaya Garg

1,525
18
23

Get collection of elements from JSON

3 Answers3