NodeJS - Extract data from a multilevel array of objects

Question

I have the following JSON array :

{
"list": [{
    "name": "Assignment",
    "id": 67,
    "template": 0,
    "children": [{
        "assignmentnumber": 1000,
        "fromCountry": "Sweden",
        "toCountry": "Spain",
        "fromCity": "Stockholm",
        "toCity": "Madrid"
    }, {
        "assignmentnumber": 15678,
        "fromCountry": "Sweden",
        "toCountry": "Germany",
        "fromCity": "Stockholm",
        "toCity": "Berlin"
    }, {
        "assignmentnumber": 10001,
        "fromCountry": "Sweden",
        "toCountry": "United Kingdom",
        "fromCity": "Stockholm",
        "toCity": "London"
    }]
}, {
    "name": "Valuation form",
    "id": 36,
    "template": 0,
    "children": [15678]
}, {
    "name": "Claim",
    "id": 12,
    "template": 0,
    "children": [1000, 10001]
}]
}

I need to extract a new array from the array containing only the 'name' element. I have tried lodash but cannot figure out how to use it properly.

Anyone who can give me a clue how to do this ?

@JPlexor, it is working for you ?

Mihai Alexandru-Ionut
– Mihai Alexandru-Ionut

2017-02-24 08:34:38 +00:00
Commented Feb 24, 2017 at 8:34 — Mihai Alexandru-Ionut
– Mihai Alexandru-Ionut, Commented Feb 24, 2017 at 8:34
It works like a charm ;-) Thank you all !

J. Plexor
– J. Plexor

2017-02-25 10:07:26 +00:00
Commented Feb 25, 2017 at 10:07 — J. Plexor
– J. Plexor, Commented Feb 25, 2017 at 10:07

Mihai Alexandru-Ionut · Accepted Answer · 2017-02-23 21:12:16Z

You should use map method, which accepts as parameter a callback function.

The map() method creates a new array with the results of calling a provided function on every element in this array.

var array=obj.list.map(callback);
function callback(item){
    return item.name;
}

Or simply:

var array=obj.list.map(el=>el.name);

var obj={
"list": [{
    "name": "Assignment",
    "id": 67,
    "template": 0,
    "children": [{
        "assignmentnumber": 1000,
        "fromCountry": "Sweden",
        "toCountry": "Spain",
        "fromCity": "Stockholm",
        "toCity": "Madrid"
    }, {
        "assignmentnumber": 15678,
        "fromCountry": "Sweden",
        "toCountry": "Germany",
        "fromCity": "Stockholm",
        "toCity": "Berlin"
    }, {
        "assignmentnumber": 10001,
        "fromCountry": "Sweden",
        "toCountry": "United Kingdom",
        "fromCity": "Stockholm",
        "toCity": "London"
    }]
}, {
    "name": "Valuation form",
    "id": 36,
    "template": 0,
    "children": [15678]
}, {
    "name": "Claim",
    "id": 12,
    "template": 0,
    "children": [1000, 10001]
}]
};
console.log(obj.list.map(function(item){
    return item.name;
}));

jchitel · Accepted Answer · 2017-02-23 21:12:30Z

0

You can do this without lodash, using native Array APIs.

const obj = { /* The JSON in your question */ };
const names = obj.list.map(item => item.name);

Array.map() takes a function and calls that function on each item of an array, returning a new array containing the result of each item.

answered Feb 23, 2017 at 21:12

jchitel

3,1795 gold badges40 silver badges52 bronze badges

Comments

Alan · Accepted Answer · 2017-02-23 21:28:20Z

0

Map is the best way to go as everyone else stated. Another alternative is use a forEach loop, specially if you want to operate with them.

var children = obj.children;
var array_of_names;

children.forEach(function (item)){
    array_of_names.push(item.name);
    //... Do more operations for each item
}

answered Feb 23, 2017 at 21:28

Alan

3893 silver badges23 bronze badges

Collectives™ on Stack Overflow

NodeJS - Extract data from a multilevel array of objects

3 Answers 3

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related