TypeScript Pick<T, K> Utility Type Explained

Understanding Pick<T, K>

Pick<T, K> constructs a type by picking the set of properties whose keys are in the union K from type T. It is the type-level equivalent of selecting specific columns from a database table.

Syntax

type Pick<T, K extends keyof T> = {
  [P in K]: T[P];
};

Basic Example

interface User {
  id: number;
  name: string;
  email: string;
  password: string;
  avatar: string;
  createdAt: Date;
}

type UserPreview = Pick<User, "id" | "name" | "avatar">;
// Equivalent to:
// {
//   id: number;
//   name: string;
//   avatar: string;
// }

Practical Pattern: API Response Shaping

// Full database model
interface Product {
  id: string;
  name: string;
  price: number;
  cost: number;
  inventory: number;
  supplier: string;
  internalNotes: string;
}

// Public API response -- excludes internal fields
type PublicProduct = Pick<Product, "id" | "name" | "price">;

// Admin API response -- includes inventory
type AdminProduct = Pick<Product, "id" | "name" | "price" | "inventory" | "supplier">;

Pick vs Omit

Pick and Omit are complementary:

• Use Pick when you want a small subset from a large type (include-list)
• Use Omit when you want most properties except a few (exclude-list)

// These produce the same result:
type A = Pick<User, "id" | "name">;
type B = Omit<User, "email" | "password" | "avatar" | "createdAt">;