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Pick Object Fields

Creates a new object containing only the specified properties from a source object.

Import​

// Main function
import { pickFields } from 'nhb-toolbox';

// Alias also available:
import { pickObjectFields } from 'nhb-toolbox';

Function Signature(s)​

function pickFields<T extends GenericObject, U extends keyof T>(
  source: T,
  keys: U[]
): { [K in U]: T[K] }

Usage​

Basic Usage​

const user = {
  id: 1,
  name: 'John',
  email: 'john@example.com',
  age: 30
};

const picked = pickFields(user, ['name', 'email']);
// Returns { name: 'John', email: 'john@example.com' }

API Reference​

Type Parameters​

NameDescription
TType of source object
UType of keys to pick

Parameters​

NameTypeDescription
sourceTSource object to pick from
keysU[]Array of property keys to pick

Returns​

A new object containing only the specified properties

Key Features​

  1. Type Safe: Maintains proper TypeScript typing
  2. Non-Destructive: Creates new object without modifying original
  3. Simple API: Easy to use with clear intent
  4. Performance: Efficient implementation

Examples​

Nested Objects​

const book = {
  title: 'Clean Code',
  author: 'Robert Martin',
  details: {
    pages: 464,
    publisher: 'Prentice Hall'
  }
};

pickFields(book, ['title', 'details']);
// Returns {
//   title: 'Clean Code',
//   details: { pages: 464, publisher: 'Prentice Hall' }
// }

With Optional Fields​

interface Product {
  id: number;
  name: string;
  price?: number;
}

const laptop: Product = {
  id: 101,
  name: 'MacBook Pro'
};

pickFields(laptop, ['name', 'price']);
// Returns { name: 'MacBook Pro', price: undefined }

Limitations​

  1. No Deep Picking: Only works with top-level properties
  2. No Dot Notation: Doesn't support nested property paths
  3. No Default Values: Returns undefined for missing properties
  • Creating view models from data objects
  • Selecting API response fields
  • Reducing payload size
  • Creating partial objects for updates
  • Data masking/redaction

Aliases​

This function is also exported as:

  • pickObjectFields