CODEWITHSUNDEEP
javascriptarraysjson
modi
modi

Reputation: 337

Merging objects from array with the same key value

I have an array which looks like this:

var arr = [
    {id: 1, tech_id:11, action: 'swim'},
    {id: 2, tech_id:11, action: 'run'},
    {id: 3, tech_id:22, action: 'climb'},
    {id: 4, tech_id:22, action: 'swim'},
    {id: 5, tech_id:11, action: 'jump'},
]

How do I make it to look like this:

[
    {tech_id: 11, data: [{id: 1, action:'swim'}, {id: 2, action:'run'}, {id: 5, action:'jump'}] }
    {tech_id: 22, data: [{id: 3, action:'climb'}, {id:4, action:'swim'}]}

]

Upvotes: 1

Views: 1437

Answers (3)

Nick Parsons
Nick Parsons

Reputation: 50639

One suggestion is to use a Map, where each key in the Map is a tech_id, and each value is an array of objects (excluding the tech_id) which have that tech_id. You can then convert the Map to an array using Array.from with an additional mapping function to convert each [key, value] pair entry in the map into an object ([tech_id, data]) => ({tech_id, data}):

const arr = [ {id: 1, tech_id:11, action: 'swim'}, {id: 2, tech_id:11, action: 'run'}, {id: 3, tech_id:22, action: 'climb'}, {id: 4, tech_id:22, action: 'swim'}, {id: 5, tech_id:11, action: 'jump'}, ];
const res = Array.from(arr.reduce((map, {tech_id,  ...r}) => 
  map.set(tech_id, [...(map.get(tech_id) || []), r])
, new Map), ([tech_id, data]) => ({tech_id, data}));

console.log(res);
.as-console-wrapper { max-height: 100% !important;} /* ignore */

Upvotes: 0

Rahul Sharma
Rahul Sharma

Reputation: 10071

You can use the Array reduce and Object Value function to get it done.

var arr = [
{id: 1, tech_id:11, action: 'swim'},
{id: 2, tech_id:11, action: 'run'},
{id: 3, tech_id:22, action: 'climb'},
{id: 4, tech_id:22, action: 'swim'},
{id: 5, tech_id:11, action: 'jump'},
]
const result = Object.values(arr.reduce((item, next) => {
if (!item[next.tech_id]) {
    item[next.tech_id] = {
        tech_id: next.tech_id,
        data: []
    };
}

item[next.tech_id].data.push(next);
return item;
}, {}));

console.log(result);

Upvotes: 0

Jack Yu
Jack Yu

Reputation: 2425

You could use reduce with Object.keys to do that.

var arr = [
    {id: 1, tech_id:11, action: 'swim'},
    {id: 2, tech_id:11, action: 'run'},
    {id: 3, tech_id:22, action: 'climb'},
    {id: 4, tech_id:22, action: 'swim'},
    {id: 5, tech_id:11, action: 'jump'},
]

let mergeObj = arr.reduce((p, c) => {
    const {tech_id, ...otherData} = c;

    if (!(tech_id in p)) {
        p[tech_id] = {
            data: []
        }
    }
    
    p[tech_id].data.push(otherData)
    return p
}, {})

mergeObj = Object.keys(mergeObj).map(key => {
    return {
        tech_id: key,
        data: mergeObj[key].data
    }
})

console.log(mergeObj);

Upvotes: 2

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