[RequireAtLeastOne] Type that requires at least one of it's properties #types

RequireAtLeastOne.ts

// https://stackoverflow.com/a/49725198/23972
export type RequireAtLeastOne<T, Keys extends keyof T = keyof T> = Pick<
  T,
  Exclude<keyof T, Keys>
> &
  {
    [K in Keys]-?: Required<Pick<T, K>> & Partial<Pick<T, Exclude<Keys, K>>>;
  }[Keys];


// Example usage that requires at least one of bar or baz

type Foo = RequireAtLeastOne<
  {
    bar?: string
    baz?: number
    somethingElse: Date
    whatever: boolean
  },
  "bar" | "baz"
>;