use Partial in nested property with typescript

Question

Say I have a type like this;

interface State {
  one: string,
  two: {
    three: {
      four: string
    },
    five: string
  }
}

I make state Partial like this Partial<State>

But how can I make on of the nested properties partial, for example if I wanted to make two also partial.

How would I do this?

question from:https://stackoverflow.com/questions/47914536/use-partial-in-nested-property-with-typescript

Answer 1

You can pretty easily define your own RecursivePartial type, which will make all properties, included nested ones, optional:

type RecursivePartial<T> = {
    [P in keyof T]?: RecursivePartial<T[P]>;
};

If you only want some of your properties to be partial, then you can use this with an intersection and Pick:

type PartialExcept<T, K extends keyof T> = RecursivePartial<T> & Pick<T, K>;

That would make everything optional except for the keys specified in the K parameter.