Renaming keys in an object using reduce method in JS

Question

Following is the object in which I want to replace countryID with value, countryName with label.

In the same object I am having localLanguages Array in which I am trying to rename language with label and languageCode with value.

array -

var obj = [{
    "countryID": "CON1010",
    "countryName": "Poland",
    "countryCode": "pl",
    "localLanguages": [{
        "language": "English",
        "languageCode": "en"
      },
      {
        "language": "Polish",
        "languageCode": "en"
      }
    ]
  },
  {
    "countryID": "CON1011",
    "countryName": "UK",
    "countryCode": "uk",
    "localLanguages": [{
      "language": "English",
      "languageCode": "en"
    }]
  }
];

Transformed to -

var obj = [{
    "value": "CON1010",
    "label": "Poland",
    "countryCode": "pl",
    "localLanguages": [{
        "label": "English",
        "value": "en"
      },
      {
        "label": "Polish",
        "value": "en"
      }
    ]
  },
  {
    "value": "CON1011",
    "label": "UK",
    "countryCode": "uk",
    "localLanguages": [{
      "label": "English",
      "value": "en"
    }]
  }
];

Code -

arr.map(x => {
  var newObj = Object.keys(x).reduce((obj, key) => {
    if (key !== 'countryID') {
      obj[key] = x[key]
    }

    if (key === 'countryID') {
      obj.value = x.countryID;
    }
  }, {})
  console.log(newObj);

  return newObj;
})

Mergim Bajrami · Accepted Answer · 2020-04-19 15:24:51Z

4

Here is a solution with es6 Destructuring and map:

 const arr = [{"countryID":"CON1010","countryName":"Poland","countryCode":"pl","localLanguages":[{"language":"English","languageCode":"en"},{"language":"Polish","languageCode":"en"}]},{"countryID":"CON1011","countryName":"UK","countryCode":"uk","localLanguages":[{"language":"English","languageCode":"en"}]}];

 const result = arr.map(item => {

  let localLanguages = item.localLanguages.map(i => {
    const { language: label, languageCode: value, ...rest } = i;
    return { label, value, ...rest };
  });

  const { countryID: value, countryName: label, ...rest } = item;

  return { value, label, ...rest, localLanguages };
});

console.log(result)

edited Apr 19, 2020 at 15:24

answered Apr 17, 2020 at 12:53

Mergim Bajrami

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2 Comments

Rotem Over a year ago

It will be better to set the code in a function, after that it will be great if you can explain what is the meaning of each step so it will be clear what are the required changes in the code. Another thing - when manipulating an object it is better to use Object.assign({}, obj) so you are manipulating on a copy of the object.

Mergim Bajrami Over a year ago

@Rotem I've changed a bit the code for more clarifications, now you can run the code and see the result. I just iterated from the arr array and created a new array with the requirements in the question above.

Ori Drori · Accepted Answer · 2020-04-17 11:52:02Z

2

Use Array.map() to convert the outer objects, and another map to convert the localLanguages:

const arr = [{"countryID":"CON1010","countryName":"Poland","countryCode":"pl","localLanguages":[{"language":"English","languageCode":"en"},{"language":"Polish","languageCode":"en"}]},{"countryID":"CON1011","countryName":"UK","countryCode":"uk","localLanguages":[{"language":"English","languageCode":"en"}]}];

const result = arr.map(o => ({
  value: o.countryID,
  label: o.countryName,
  countryCode: o.countryCode,
  localLanguages: o.localLanguages.map(l => ({
    value: l.languageCode,
    label: l.language
  }))
}));

console.log(result)

answered Apr 17, 2020 at 11:52

Ori Drori

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Comments

Aleksey · Accepted Answer · 2020-04-17 11:58:52Z

0

You have forgotten to return obj value in the reduce function

 var newObj = Object.keys(x).reduce( (obj, key) => {
    if(key !== 'countryID') {
      obj[key] = x[key]
    }

    if(key === 'countryID') {
      obj.value = x.countryID;
    }
  }, {})

answered Apr 17, 2020 at 11:58

Aleksey

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Comments

Denis Pavlov · Accepted Answer · 2020-04-17 12:08:29Z

0

Here the function to change the keys. Use it with every element of you array
recursively, but check the type of every element

function changeKeys(obj) {
  const rename = {
    'countryID': 'value',
    'countryName': 'label',
    'language': 'label',
    'languageCode': 'value'
  }
  return Object.keys(obj)
    .reduce(
    (acc, rec) => {
      if (typeof rename[rec] !== 'undefined') {
        return {...acc, [rename[rec]]: obj[rec]}
      }
      return {...acc, [rec]: obj[rec]}
    }, {}
  )
}

answered Apr 17, 2020 at 12:08

Denis Pavlov

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