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?

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.

Answer 2

This is possible, you can create a 'deep' partial type as followed:

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

Which can be used as followed

const state: DeepPartial<State> = {     two: {         three: {             four: '4'         }     } }