Nested array in JSON object, add key if not exists and value as empty

Question

Currently, I have a nested array in JSON object. I would like to define the key and value for the following:

• contact as "phone": "", "email" : "", "fax": "", "website": ""
• address as "city": "", "country": "", "house_number": "", "street name": ""

If one of these keys is missing, it needs to be filled as a default key and value as shown in the expected input.

Could anyone help how to do it in JavaScript?

Current Input:

{
  "data": [
    {
      "name": "John",
      "contact": {
        "phone": "987-654-3210",
        "email": "[email protected]"
      },
      "address": {
        "city": "Berlin",
        "country": "Germany"
      }
    }
  ]
}

Expected Input:

{
  "data": [
    {
      "name": "John",
      "contact": {
        "phone": "987-654-3210",
        "email": "[email protected]",
        "fax": "",
        "website": ""
      },
      "address": {
        "city": "Berlin",
        "country": "Germany",
        "house_number": "",
        "street name": ""
      }
    }
  ]
}

Answer 1

If you don't mind to mutate your original array, here's one solution:

const templates = {
  contact: {
    "phone": "",
    "email": "",
    "fax": "",
    "website": ""
  },
  address: {
    "city": "",
    "country": "",
    "house_number": "",
    "street name": ""
  }
}

source.data.forEach(entry => Object.entries(templates).forEach(([key, template]) => {
  entry[key] = entry[key] || {};
  Object.entries(template).forEach(([k, v]) => {
    entry[key][k] = entry[key][k] || v;
  });
}));

const source = {
  "data": [{
    "name": "John",
    "contact": {
      "phone": "987-654-3210",
      "email": "[email protected]"
    },
    "address": {
      "city": "Berlin",
      "country": "Germany"
    }
  }, {
    "name": "Bob",
    "contact": {
      "phone": "123-456-7890",
      "fax": "9876-5432",
      "website": "bob.example.com"
    },
    "address": {
      "city": "NYC",
      "country": "USA",
      "house_number": "701A"
    }
  }]
};

const templates = {
  contact: {
    "phone": "",
    "email": "",
    "fax": "",
    "website": ""
  },
  address: {
    "city": "",
    "country": "",
    "house_number": "",
    "street name": ""
  }
}

source.data.forEach(entry => Object.entries(templates).forEach(([key, template]) => {
  entry[key] = entry[key] || {};
  Object.entries(template).forEach(([k, v]) => {
    entry[key][k] = entry[key][k] || v;
  });
}));

console.log(source);