Merge 2 json array objects based on a common property

Question

I got 2 Json arrays with some common field. But they are not sorted in any specific order. I want to be able to merge them based on a property.

var merge = require('deepmerge');
var one = [{
  id:1
},
{
  id:2
}];
var two = [{
  id:2,
  name:"test1"
},
{
  id:1,
  name:"test2"
}];

console.log(merge(one,two));

deepmerge results in blind merge, first element with first element from the other array.

[ { id: 2, name: 'test1' }, { id: 1, name: 'test2' } ]

I know its possible to manually iterate thru one array, find the matching node from the other array and merge them...wondering if there is any library to do this. Thoughts?

@nina I got 2 unsorted arrays but with atleast one common property like I mentioned above and want to merge them. Does that help? — Sahas
– Sahas, Commented Jun 27, 2016 at 11:51
not really, please add some more example. and the wanted result of merging. — Nina Scholz
– Nina Scholz, Commented Jun 27, 2016 at 11:53
want one merged array as a result, like [ { id: 1, name: 'test2' }, { id: 2, name: 'test1' }, { id: 3, name: 'test3' } ] — Sahas
– Sahas, Commented Jun 27, 2016 at 11:55

Hugolpz · Accepted Answer · 2021-12-09 10:11:11Z

3

You could use a function and define the common key, on which the merging should group. It works with unsorted data.

function merge(arrays, key) {
    var r = [],
        hash = Object.create(null);

    arrays.forEach(function (a) {
        a.forEach(function (o) {
            if (!hash[o[key]]) {
                hash[o[key]] = {};
                r.push(hash[o[key]]);
            }
            Object.keys(o).forEach(function (k) {
                hash[o[key]][k] = o[k];
            });
        });
    });
    return r;
}

var one = [{ id: 1, score: 100 }, { id: 2, score: 200 }, { id: 4, score: 400 }],
    two = [{ id: 2, name: "test1" }, { id: 1, name: "test2" }, { id: 3, name: "test3" }],
    merged = merge([one, two], 'id');

console.log(merged);

edited Dec 9, 2021 at 10:11

Hugolpz

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answered Jun 27, 2016 at 12:32

Nina Scholz

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Comments

Andreas Louv · Accepted Answer · 2016-06-27 11:51:18Z

0

Sort both arrays before hand?

one.sort((a, b) => a.id - b.id);
two.sort((a, b) => a.id - b.id);

Now that the arrays are sorted you should be able to merge them properly:

console.log(merge(one, two));

answered Jun 27, 2016 at 11:51

Andreas Louv

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1 Comment

Sahas Over a year ago

thanks.. I did try this.. it didn't work when I've an array element in 1st array that doesn't have any matching in 2nd. Below is an example Sorted array - one [ { id: 1 }, { id: 2 }, { id: 4 } ] sorted array - two [ { id: 1, name: 'test2' }, { id: 2, name: 'test1' }, { id: 3, name: 'test3' } ] merges array [ { id: 1, name: 'test2' }, { id: 2, name: 'test1' }, { id: 3, name: 'test3' } ]

Anirudha · Accepted Answer · 2016-06-27 12:04:25Z

0

I think you are looking for merge in lodash. Subsequent sources overwrite property assignments of previous sources. So this will overwrite the subsequent id's

var users = {
  'data': [{ 'user': 'barney' }, { 'user': 'fred' }]
};

var ages = {
  'data': [{ 'age': 36 }, { 'age': 40 }]
};

_.merge(users, ages);
// → { 'data': [{ 'user': 'barney', 'age': 36 }, { 'user': 'fred', 'age': 40 }] }

edited Jun 27, 2016 at 12:04

answered Jun 27, 2016 at 11:58

Anirudha

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