Convert single element in array of objects

Question

I am trying to convert all elements of a given key in a list of objects. The specific change is to convert an generic object to a Long object with the same values.

Input:

[obj1, obj2, obj3, ...]

Where each object looks like:

{
    key1: value1, // value1 is an object
    key2: value2
}

So the goal here is to get a very similar array, but where key1 is transformed from just object to a long object, in my example incremented by one.

Output:

[obj1, obj2, obj3]

Where each object is:

{
    key1: value1, // value1 is now a Long object
    key2: value2
}

I tried with mapping over the array and then spreading over the objects entries, but did not succeed.

Any help would be highly appreciated.

please add some real example with the wanted result, beside the code, you tried. — Nina Scholz
– Nina Scholz, Commented Mar 9, 2017 at 14:57
Thanks for the comments. I updated the question to be more specific. I also added an answer below with the final solution. — psv
– psv, Commented Mar 10, 2017 at 8:36

dfsq · Accepted Answer · 2017-03-09 14:55:11Z

1

You don't really need to map here, unless you want to create one more new array. Simple loop would be enough, just update key1 or each object:

[obj1, obj2, obj3].forEach(obj => {
  obj.key1 = obj.key1 + 1
})

answered Mar 9, 2017 at 14:55

dfsq

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Comments

ajai Jothi · Accepted Answer · 2017-03-09 15:05:27Z

0

Since the array holds object - any modification to object reflect the actual input being passed. You need to make a copy of your object and perform the logic.

Your logic,

var input = [obj1, obj2, obj3];
var output = input.map(function(obj){
    obj.key1 = obj.key1 + 1;
    return obj;
});

console.log(input[0]===output[0]); //true

Solution:

var output = input.map(function(obj){
    var _objCopy = Object.assign({}, obj);
    _objCopy.key1 = _objCopy.key1 + 1;
    return _objCopy;
});

console.log(input[0]===output[0]); //false

answered Mar 9, 2017 at 15:05

ajai Jothi

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Comments

Danish · Accepted Answer · 2017-03-09 15:06:49Z

0

how about dynamically first key of any object es6 way

 const myObject0 = {
           'foo1': { name: 'myNam1' },
           'foo2': { name: 'myNam2' }
        };

        const myObject1 = {
           'yo': { name: 'myNam1' },
           'boh': { name: 'myNam2' }
        };


        [myObject0, myObject1].forEach(obj => {
            let getFirstKey = Object.keys(obj)[0];
            getFirstKey = getFirstKey + 1;
            console.log(getFirstKey);

        });

answered Mar 9, 2017 at 15:06

Danish

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Comments

psv · Accepted Answer · 2017-03-13 20:50:24Z

0

Thanks for all the answers guys.

I ended up with the following:

Given the input

[
    {
        key1: value1, // value1 is an object
        key2: value2
    },

    {
        key1: value1, // value1 is also an object
        key2: value2
    }
]

Solution: I ended up with,

  const testvar = [obj1, obj2, obj3].map((obj) => {
    return {
      ...obj,
      key1: new Long.fromValue(obj.key1)
    }
  });

  console.log(testvar);

Which gives the output

[
    {
        key1: value1, // value1 is now a Long object
        key2: value2
    },

    {
        key1: value1, // value1 is also now a Long object
        key2: value2
    }
]

edited Mar 13, 2017 at 20:50

answered Mar 10, 2017 at 8:18

psv

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