How to remove several items from an array of JSON objects in TypeScript

Question

I have a JSON object that I want to remove a series of items from:

const addressNonRequired = ["addr_linkid_usr", "addr_created", "addr_updated"]

I know I can use the 'delete' method, but how would I use the above array to do the same:

// remove non-required data
addressesFound.forEach(row => (
  // delete row.addr_linkid_usr,
  // delete row.addr_created,
  // delete row.addr_updated
  addressNonRequired.forEach(item => (
    delete row[item];
  ));
));

I've tried several ways to get this to work, not sure if I'm looking at it the right way .... ?

Example of array provided:

[
  {
    "addr_id": "41d86d46-8b19-4f4e-be03-f9915ef4947b",
    "addr_type": "postal",
    "addr_linkid_usr": "user1",
    "addr_created": "2021-03-10",
    "addr_updated": "",
    "addr_active": true,
    "addr_postal_as_residential": false,
    "addr_international": false,
    "addr_autocomplete_id": null
  },
  {
    "addr_id": "b18c2ca6-29cf-4114-9067-b37fd3394638",
    "addr_type": "residential",
    "addr_linkid_usr": "user1",
    "addr_created": "2021-03-10",
    "addr_updated": "",
    "addr_active": true,
    "addr_postal_as_residential": true,
    "addr_international": true,
    "addr_autocomplete_id": "string"
  }
]

Expected output:

[
  {
    "addr_id": "41d86d46-8b19-4f4e-be03-f9915ef4947b",
    "addr_type": "postal",
    "addr_active": true,
    "addr_postal_as_residential": false,
    "addr_international": false,
    "addr_autocomplete_id": null
  },
  {
    "addr_id": "b18c2ca6-29cf-4114-9067-b37fd3394638",
    "addr_type": "residential",
    "addr_active": true,
    "addr_postal_as_residential": true,
    "addr_international": true,
    "addr_autocomplete_id": "string"
  }
]

Your example fails with: Argument of type 'Address' is not assignable to parameter of type 'string'. — neophytte
– neophytte, Commented Mar 10, 2021 at 2:36

pkumar · Accepted Answer · 2021-03-10 02:44:36Z

You'll have to iterate over the addressesFound array, and in each object iterate over the keys of that object, compare if that key exists in addressNonRequired array and remove it, if applicable.

var addressesFound = [{
    "addr_id": "41d86d46-8b19-4f4e-be03-f9915ef4947b",
    "addr_type": "postal",
    "addr_linkid_usr": "user1",
    "addr_created": "2021-03-10",
    "addr_updated": "",
    "addr_active": true,
    "addr_postal_as_residential": false,
    "addr_international": false,
    "addr_autocomplete_id": null
  },
  {
    "addr_id": "b18c2ca6-29cf-4114-9067-b37fd3394638",
    "addr_type": "residential",
    "addr_linkid_usr": "user1",
    "addr_created": "2021-03-10",
    "addr_updated": "",
    "addr_active": true,
    "addr_postal_as_residential": true,
    "addr_international": true,
    "addr_autocomplete_id": "string"
  }
];

const addressNonRequired = ["addr_linkid_usr", "addr_created", "addr_updated"];

var updatedAddresses = addressesFound.map(function(address) {
    Object.keys(address).forEach(function(key) { // For each address object, iterate over the keys
    if (addressNonRequired.includes(key)) {
      delete address[key]; // Check if the key is present in the addressNonRequired array. Delete if present
    }
  });
  return address;
});

console.log(updatedAddresses);

John Michael Manlupig · Accepted Answer · 2021-03-10 02:56:09Z

I always use this very often when filtering an object or an array of objects.

I usually have these in my helpers.ts file. They also make sure that the keys you are filtering does exist in the object and it also has autocomplete.

export function except<T, K extends keyof T>(data: T, keys: Array<K>) {
    const copy = { ...data };
    for (const key of keys) {
        if (key in copy) {
            delete copy[key];
        }
    }
    return copy;
}

export function exceptMany<T, K extends keyof T>(data: Array<T>, keys: Array<K>) {
    return [...data].map((item) => except(item, keys));
}

Then to filter an array of objects, we do:

const data = [
  {
    "addr_id": "41d86d46-8b19-4f4e-be03-f9915ef4947b",
    "addr_type": "postal",
    "addr_linkid_usr": "user1",
    "addr_created": "2021-03-10",
    "addr_updated": "",
    "addr_active": true,
    "addr_postal_as_residential": false,
    "addr_international": false,
    "addr_autocomplete_id": null
  },
  {
    "addr_id": "b18c2ca6-29cf-4114-9067-b37fd3394638",
    "addr_type": "residential",
    "addr_linkid_usr": "user1",
    "addr_created": "2021-03-10",
    "addr_updated": "",
    "addr_active": true,
    "addr_postal_as_residential": true,
    "addr_international": true,
    "addr_autocomplete_id": "string"
  }
];

const results = exceptMany(data, ['addr_linkid_usr', 'addr_created', 'addr_updated']);

Filtering keys from just one object is also possible:

const single = {
    "addr_id": "41d86d46-8b19-4f4e-be03-f9915ef4947b",
    "addr_type": "postal",
    "addr_linkid_usr": "user1",
    "addr_created": "2021-03-10",
    "addr_updated": "",
    "addr_active": true,
    "addr_postal_as_residential": false,
    "addr_international": false,
    "addr_autocomplete_id": null
};

const filteredSingle = except(single, ['addr_linkid_usr', 'addr_created', 'addr_updated']);

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