Aggregate array of object to single distinct value of object javascript

Question

I want to aggregate array of object into single object with each object having distinct value. But My code is not giving me desired output. Can someone please help me?

My Input : 
    [{
        "obj1" : "value1",
        "obj2" : ["abc", "def"],
        "obj3" : ["ghi"],
        "obj4" : "value4",
    },
    {
        "obj1" : "value2",
        "obj2" : ["abc", "mno"],
        "obj3" : ["klm"],
        "obj4" : "value4",
    }]


Output I want:
{
    "obj1" : ["value1","value2"]
    "obj2" : ["abc", "def","mno"],
    "obj3" : ["ghi","klm"],
    "obj4" : ["value4"]
}

My Code:
const result = filterData.reduce((a,c) => 
  (Object.keys(c).map(k => a[k] = [...a[k] || [], c[k]]), a), {})

Hassan Imam · Answer 1 · 2021-03-10T10:15:30.177

4

You can create a single object from an array of objects using array#reduce. You can get distinct value using Set.

const data = [{ "obj1" : "value1", "obj2" : ["abc", "def"], "obj3" : ["ghi"], "obj4" : "value4", }, { "obj1" : "value2", "obj2" : ["abc", "mno"], "obj3" : ["klm"], "obj4" : "value4", }],
      result = data.reduce((r,o) => {
        Object.keys(o).forEach(k => {
          r[k] = [...new Set((r[k] || []).concat(o[k]))];
        });
        return r;
      },{});
console.log(result);

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

edited Mar 10 '21 at 10:15

answered Mar 10 '21 at 08:02

Hassan Imam

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Why do we need r[k] = r[k] || []; line? To check if the key exists? – Richard Rublev Mar 10 '21 at 09:43
1

It was initializing the array for the new key and the old key, it was not doing anything. I have updated the code – Hassan Imam Mar 10 '21 at 10:15
1

Great,it is much easier now to understand. – Richard Rublev Mar 10 '21 at 11:09

score 2 · Accepted Answer · answered Mar 10 '21 at 07:59

Here I use some helpers from lodash to solve your problem.

const input = [{
        "obj1" : "value1",
        "obj2" : ["abc", "def"],
        "obj3" : ["ghi"],
        "obj4" : "value4",
    },
    {
        "obj1" : "value2",
        "obj2" : ["abc", "mno"],
        "obj3" : ["klm"],
        "obj4" : "value4",
    }]
    
function customizer(objValue, srcValue) {
  if (_.isArray(objValue)) {
    return _.union(objValue, srcValue);
  }
}
    
const output = input.reduce((acc, cur) => {
  const modifiedCur = _.mapValues(cur, function(o) { return typeof o === 'string' ? [o]: o; }); 
  acc = _.mergeWith(acc, modifiedCur, customizer);
  return acc
},{})    
    
console.log(output)

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.21/lodash.min.js"></script>

Aggregate array of object to single distinct value of object javascript

2 Answers2