Typescript RecursiveRequired generic type

recursive-required.ts

type RecursiveRequired<T> = Required<{
  [P in keyof T]: T[P] extends object | undefined ? RecursiveRequired<Required<T[P]>> : T[P];
}>;

type ExampleType = {
  a?: number;
  b: number;
  c?: {
    d?: {
      e?: number;
      f: boolean;
      g?: {
        h: string
      }
    }
  }
}

type ExampleTypeRequired = RecursiveRequired<ExampleType>

const data: ExampleTypeRequired = {
  a: 1,
  b: 1,
  c: {
    d: {
      e: 1,
      f: false,
      g: {
        h: 'hello'
      }
    }
  }
}

@gomezcabo Yes, that does the trick nicely! Thanks!

Just for my own academic curiosity, do you know why the TS compiler was saying 'string' is not assignable to type 'DeepRequired<keyof T>'? It seems like they should be compatible.

I guess when passing down the keyof T to the generic, this one could be string, number or symbol and that's where the Type was failing. No way to determine which one of those. That's why the fix was to include the check T[K] extends PropertyKey (PropertyKey === string | number | symbol).