Type of idKey is not recognized correctly when using generics about platform

[markostanimirovic]

I opened an issue in the TS repo: microsoft/TypeScript#57318

As a workaround, you can use conditional type: example

[markostanimirovic]

@Raul52

export type EntityIdProps<Entity> = {
    [K in keyof Entity as K extends EntityId ? K : never]: Entity[K];
};

👆 By applying the changes that you proposed, the EntityIdProps type will always return all props because K extends EntityId will always be true (except when some key is a symbol).

---

The idea with:

export type EntityIdProps<Entity> = {
    [K in keyof Entity as Entity[K] extends EntityId ? K : never]: Entity[K];
};

is to exclude all properties whose values are not string | number (not keys), because they cannot be used as identifiers.

---

But anyway, thanks for reporting this! Let's try to find some workaround.

[Raul52]

@markostanimirovic I created a complete test case and you are right, my proposed solution was wrong.

test-case

Will also actively check for a solution given the intention - which is to allow keys whose values are `string | number', but not other types.

[markostanimirovic]

microsoft/TypeScript#48992