Merge two array of objects based on a key value compare

Question

I'm trying to merge two objects which, both have same similar key, but different values. I want them to keep the different keys and but place them together in the matching key value

here my first obj,

const obj1 = [
      {
        "p_id": 1,
        "name": "Peter",
        "status" : "Active"
      },
      {
        "p_id": 2,
        "name": "Kane",
        "status" : "Active"
      },
      {
        "p_id": 3,
        "name": "William",
        "status" : "Inactive"
      }
]


}

my second obj,

const obj2 = [
  { p_id: 1, type: 'home', no: '+01 234 5678' },
  { p_id: 1, type: 'work', no: '+09 111 2223' },
  { p_id: 2, type: 'home', no: '+12 345 6789' },
]

Actually I did something like this,

 obj1.forEach((item) => {
            Object.assign(item, {
                phone: obj2.find(
                    (o) => o.p_id === item.p_id
                )
            });
        });
// console.log(obj1) would be

[
      {
        "p_id": 1,
        "name": "Peter",
        "status" : "Active",
        "phone" : {type: 'home', no: '+01 234 5678'}       
      },
      {
        "p_id": 2,
        "name": "Kane"
        "status" : "Active",
        "phone" : {type: 'home', no: '+12 345 6789'} 
      },
      {
        "p_id": 3,
        "name": "William"
        "status" : "Inactive"
        "phone" : undefined
      }

]

but this is not I want. I want to be final result I need is the compare between these arrays – the final result should be like this:

const result = [
      {
        "p_id": 1,
        "name": "Peter",
        "status" : "Active",
        "phone" : [
           {type: 'home', no: '+01 234 5678'},
           {type: 'work', no: '+09 111 2223'}        
        ]
      },
      {
        "p_id": 2,
        "name": "Kane"
        "status" : "Active",
        "phone" : [
           {type: 'home', no: '+12 345 6789'}      
        ]
      },
      {
        "p_id": 3,
        "name": "William"
        "status" : "Inactive"
        "phone" : []
      }

]

Really appreciate your kind help, Thank you!

This is not a code-writing service. Show us an actual attempt you made, and give a proper explanation of what exactly the problem was with it. How to Ask, minimal reproducible example — C3roe
– C3roe, Commented Jul 9, 2021 at 7:53
@CBroe sure I understand, actually I did tried some different different method.. but finally I'm able to reach out something like this updated question. (I updated the question). Thanks — supunbatagoda
– supunbatagoda, Commented Jul 9, 2021 at 8:04

Manas Khandelwal · Accepted Answer · 2021-07-09 08:17:49Z

You can do something like this:

const users = [
  {
    p_id: 1,
    name: "Peter",
    status: "Active",
  },
  {
    p_id: 2,
    name: "Kane",
    status: "Active",
  },
  {
    p_id: 3,
    name: "William",
    status: "Inactive",
  },
];

const phoneNumbers = [
  { p_id: 1, type: "home", no: "+01 234 5678" },
  { p_id: 1, type: "work", no: "+09 111 2223" },
  { p_id: 2, type: "home", no: "+12 345 6789" },
];

const mergeArrays = (arr1, arr2) => {
  return arr1.map((obj) => {
    const numbers = arr2.filter((nums) => nums["p_id"] === obj["p_id"]);
    if (!numbers.length) {
      obj.phone = numbers;
      return obj;
    }
    obj.phone = numbers.map((num) => ({ type: num.type, no: num.no }));
    return obj;
  });
};

const result = mergeArrays(users, phoneNumbers);
console.log(result);

Explanation:

Use the filter method to find all the objects with the same id in the phoneNumbers array. Then loop using the map method on the phone numbers matched and return a phone number object without the id.

Spectric · Accepted Answer · 2021-07-09 14:04:09Z

2

Instead of Array.find try Array.filter method. find will only return the first element while filter will return all the elements which meet the condition:

Object.assign(item, {
    phone: obj2.filter(
       (o) => o.p_id === item.p_id
    )
 });

edited Jul 9, 2021 at 14:04

Spectric

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answered Jul 9, 2021 at 8:08

Shuvo

1,2939 silver badges18 bronze badges

2 Comments

supunbatagoda Over a year ago

Thank you, actually this small code snippet tally with my solutions, but one thing @Shuvo final result phone attribute has p_id property as well. Is there anything to remove this p_id form result.phone object array would be nice

Shuvo Over a year ago

You can chain the map method to pick the properties you need: phone: obj2.filter((o) => o.p_id === item.p_id ).map(item => ({type: item.type, no: item.no}))

Ernesto · Accepted Answer · 2021-07-09 14:46:09Z

-1

Here the best way to do so


// intersect can be simulated via
const intersection = new Set([...mySet1].filter(x => mySet2.has(x)))

// difference can be simulated via
const difference = new Set([...mySet1].filter(x => !mySet2.has(x)))

answered Jul 9, 2021 at 14:46

Ernesto

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