Making an array of object a value of a object in Array in Node.js

Question

I have two arrays of objects. example

 data1 = [{
     foo: '2',
     box: 'yes',
     id: '1234'
 }, {
     foo: '34',
     box: 'no',
     id: '1235'
 }];

 data2 = [{
     key: 'value',
     key: 'value',
     id: '1234'
 }, {
     key: 'value',
     key: 'value',
     id: '1235'
 }];

I need it like this based on matching id value : each obj has a unique key id, that much the second array.

finalData = [{
    foo: '2',
    box: 'yes',
    id: '1234',
    key: 'value',
    key: 'value'
}, {
    box: '34',
    box: 'no',
    id: '1235',
    key: 'value',
    key: 'value'
}];

basically merging the two arrays of objects based on key id .

Thanks, that works perfectly fine. what if on the objects I want to keep the key names that match but has a different value. — Navid Yousefzai
– Navid Yousefzai, Commented May 5, 2018 at 18:40

Ankit Agarwal · Accepted Answer · 2018-05-05 08:49:48Z

3

Use Object.assign for this so that you can combine the array with the common id value, use find having condition that compares the id of both the objects.

var data1 =[ {foo:'2',box:'yes',id:'1234'},{foo:'34',box:'no',id:'1235'} ]; 
var data2 =[{key:'value',key2:'value2', id:'1234'},{key:'value',key2:'value2', id:'1235'}];

data1.map(x => Object.assign(x, data2.find(y => y.id == x.id)));

console.log(data1);

Since you have same key name multiple times which is ignored by the JSON object so I have taken a new property name key2 for this example.

answered May 5, 2018 at 8:49

Ankit Agarwal

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1 Comment

CertainPerformance Over a year ago

Don't use map unless the mapped array is used. Otherwise, use forEach. Your answer also mutates the original objects in data1.

tjadli · Accepted Answer · 2018-05-05 08:53:08Z

3

building on @Ankit answer, you can use the spread operator too !! something like this

var data1 =[ {foo:'2',box:'yes',id:'1234'},{foo:'34',box:'no',id:'1235'} ]; 
var data2 =[{key:'value',key2:'value2', id:'1234'},{key:'value',key2:'value2', id:'1235'}];

const arr = data1.map(x => ({ ...x, ...data2.find(y => y.id == x.id)}));

console.log(arr);

answered May 5, 2018 at 8:53

tjadli

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Comments

Narendra Jadhav · Accepted Answer · 2018-05-05 09:09:22Z

You can also use reduce(), find() of array and Object.assign() to get required result.

DEMO

const data1 = [{foo: '2',box: 'yes',id: '1234'}, {foo: '34',box: 'no',id: '1235'}],
data2 = [{key: 'value',key1: 'value',id: '1234'}, {key: 'value',key1: 'value',id: '1235'}];
  
  let result = data1.reduce((r,{id,...rest})=>{
     let find=data2.find(o=>o.id==id);
     if(find){
        r.push(Object.assign(rest,find));
     }
     return r;
  },[])
  
  console.log(result)

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

Mohammad Usman · Accepted Answer · 2018-05-05 11:08:40Z

Here is another alternative to achieve this:

Iterate over first array and create a new Map object where ids will be used as keys and relevant object as its value.
Iterate over second array and update corresponding objects with same ids using Object.assign() in Map object.
Return an array of updated objects in Map object.

Demo:

let data1 = [{foo: '2', box: 'yes', id: '1234'}, {foo: '34', box: 'no', id: '1235'}],
    data2 = [{key1: 'value', key2: 'value', id: '1234'}, {key1: 'value', key2: 'value', id: '1235'}];

let merge = (d1, d2, m = new Map(d1.map(o => [o.id, o]))) => (
              d2.forEach(o => m.set(o.id, Object.assign(m.get(o.id), o))),
              [...m.values()]
            );
            
console.log(merge(data1, data2));

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

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