Strongly typed sort order

strongly-typed-sort-order.ts

// Example entity
export interface IPerson {
  firstName: string,
  lastName: string,
  age: number,
}

type SortOrder = 'asc' | 'desc'; // ascending or descending

type OrderByKeys<T> = `${keyof T & string}:${SortOrder}`[]

type OrderByObject<T> = Partial<Record<keyof T, SortOrder>>;

type OrderBy<T> = OrderByKeys<T> | OrderByObject<T>;


const sortByKeys: OrderBy<IPerson> = ['firstName:asc', 'age:desc']; // ✅

const sortByObject: OrderBy<IPerson> = {
    firstName: 'asc', // ✅
    age: 'desc', // ✅
    // whatever:asc // ❌
}