Typescript 相同键但不同类型嵌套（keyof 但嵌套）

Question

I am trying to created a custom type that replaces all types of a Generic parameter T to string[] but keeps all the property names even nested.

Expected behaviour: No error

interface Bar {
    lat: string,
    lng: string
}
interface Foo {
    id: string,
    bar: Bar
}
export type PartialDeepKeyOf<T> = { [id in keyof T]: string[] }

const baz: PartialDeepKeyOf<Foo> = {
    id: ['a','b'],
    bar: {
        lat: ['a','b'],
        lng: ['a','b'],
    }
}

Actual behaviour:

Type '{ lat: string[]; lng: string[]; }' is not assignable to type 'string[]'

Answer 1

You need recursive type traversal

type PartialDeepKeyOf<T> = {
    [P in keyof T]: T[P] extends string
    ? string[]
    : PartialDeepKeyOf<T[P]>
};

Playground