How to replace an object in object array in javascript (lodash)

Question

I have following object array:

var arr = [
  {
    id    : "a1",
    guid  : "sdfsfd",
    ...
    value : "abc",
    status: false
  },
  {
    id    : "a2",
    guid  : "sdfsfd",
    ...
    value : "def",
    status: true
  },
  ...
]

I have this object:

var obj = {
  id      : "a1",
  guid    : "sdfsfd",
  ...
  value   : "xyz",
  status  :  true
}

I need to replace the object in the array with this object where the "id" is same. So the resulting array will be:

var arr = [
  {
    id    : "a1",
    guid  : "sdfsfd",
    ...
    value : "xyz",
    status: true
  },
  {
    id    : "a2",
    guid  : "sdfsfd",
    ...
    value : "def",
    status: true
  },
  ...
]

Additionally I need to add this object to the array if an object with that id doesn't exists.

How to achieve this using minimal lodash code? Looking for something like

arr = _.merge_by_key(arr,obj,"id");

Community · Accepted Answer · 2017-05-23 12:17:23Z

10

you can do it with _.unionBy

var res = _.unionBy([obj], arr, 'id');

but check a note at this comment

edited May 23, 2017 at 12:17

CommunityBot

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answered Feb 16, 2017 at 6:37

stasovlas

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3 Comments

castletheperson Over a year ago

This is very creative, but may do a lot more work than needed. It will search through the rest of the items in the array to also remove duplicates.

stasovlas Over a year ago

@4castle i dont sure about "remove duplicates", can you show proof?

castletheperson Over a year ago

Observe the output in this JSFiddle.

guest271314 · Accepted Answer · 2017-02-16 06:31:24Z

7

You can use .findIndex()

var i = arr.findIndex(o => o.id === obj.id);
if (arr[i]) { arr[i] = obj } else { arr.push(obj) };

edited Feb 16, 2017 at 6:31

answered Feb 16, 2017 at 6:02

guest271314

1

2 Comments

Aleksandar Over a year ago

This is the best solution, as it doesn't require any external libraries. Thanks!

alxpez Over a year ago

Very elegant approach +1

castletheperson · Accepted Answer · 2017-02-16 06:49:26Z

3

You can use _.findIndex with the _.matchesProperty shorthand:

var index = _.findIndex(arr, ['id', obj.id]);
arr[index >= 0 ? index : arr.length] = obj;

var arr = [{
  id: "a1",
  guid: "sdfsfd",
  value: "abc",
  status: false
}, {
  id: "a2",
  guid: "sdfsfd",
  value: "def",
  status: true
}];

var obj = {
  id      : "a1",
  guid    : "sdfsfd",
  value   : "xyz",
  status  :  true
};

var index = _.findIndex(arr, ['id', obj.id]);
arr[index >= 0 ? index : arr.length] = obj;
                        
console.log(arr);

.as-console-wrapper { min-height: 100% !important; }

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.4/lodash.js"></script>

edited Feb 16, 2017 at 6:49

answered Feb 16, 2017 at 6:22

castletheperson

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Comments

ryeballar · Accepted Answer · 2017-02-16 09:05:32Z

Here's a lodash solution that uses keyBy to create an object wherein each item in the collection is represented by their id, set to override the new object or possibly add the new object and lastly values to get the array representation of the object.

var result = _(arr).keyBy('id').set(obj.id, obj).values().value();

var arr = [
  {
    id    : "a1",
    guid  : "sdfsfd",
    value : "abc",
    status: false
  },
  {
    id    : "a2",
    guid  : "sdfsfd",
    value : "def",
    status: true
  }
];

var obj = {
  id      : "a1",
  guid    : "sdfsfd",
  value   : "xyz",
  status  :  true
}

var result = _(arr).keyBy('id').set(obj.id, obj).values().value();

console.log(result);

body > div { min-height: 100%; top: 0; }

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.4/lodash.js"></script>

Asad Sarwar · Accepted Answer · 2017-02-16 09:41:29Z

1

you can loop and use 'splice' function:

var added = false;
for(var i=0;i<arr.length; i++){
   if(arr[i].id === obj.id){
        arr.splice(i,1,obj);
        added = true;
        break;
   }
}

if(!added) arr.push(obj);

EDIT: missed added condition

edited Feb 16, 2017 at 9:41

answered Feb 16, 2017 at 6:03

Asad Sarwar

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1 Comment

castletheperson Over a year ago

This won't add the object if the id wasn't found in the array.

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