Typescript - Self reference with generic property

Question

Is it possible to have a self-referenced type representation like this?

export type SelfReferenced {
    prop: string;
    [x: string]: SelfReferenced;
}

It means that all keys will be a reference of this except prop field Ex:

const $deep: SelfReference = createProxy();
let lastReference = $deep.a.very.long.nested.deep; //type: SelfReference
lastReference.prop //type: string

Additional requirement is using generic type parameter in prop:

export type SelfReferenced<T> {
    prop: () => T;
    [x: string]: SelfReferenced<T>;
}

The problem I see is that `prop` key is of type string & then `[x: string]` will conflict. If you can make one of these key types something else then it'll work or I guess inherit the other part? — MiKr13, Nov 06 '21 at 13:44
You can make a self reference easily, but you can't make one where the `prop` property is incompatible with all the other properties. See https://stackoverflow.com/questions/61431397/how-to-define-typescript-type-as-a-dictionary-of-strings-but-with-one-numeric-i for various workarounds — jcalz, Nov 06 '21 at 18:39
[Here](https://tsplay.dev/WyOvxN) is the code from the answer there translated to this example. — jcalz, Nov 06 '21 at 18:46

Aleksey L. · Accepted Answer · 2021-11-07T13:12:34.333

2

It could be represented by intersection:

type SelfReferenced = {
    prop: string;
} & { [x: string]: SelfReferenced; }

Playground

Update: Workaround for self-referencing recursive type with generics:

interface _SelfReferenced<T> { [x: string]: SelfReferenced<T>; }
type SelfReferenced<T> = _SelfReferenced<T> & { prop: () => T }

Playground

edited Nov 07 '21 at 13:12

answered Nov 06 '21 at 13:43

Aleksey L.

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Thanks, Things is I as trying with generic but there must be some bug which it doesn't allow to make it work deep.. like [here](https://www.typescriptlang.org/play?#code/C4TwDgpgBAyhA2AzAShREBOEB2BjCAJgDwAqAfFALxQDeAUFI1GBgPZgBcUAzsBgJbYA5gG46AXygAyWlADaADy68BwgLpc4SVOix5CpMiKji6dAhFzwAhlii5W2XlAAkFiJ1gIUaTDnzENPwEHNgArgC2AEaY4kZ08BDAUDa8On76VK7uYAB01rkAbpggufCOQrnYELyEuTnGAPSNoJCa3ul6+AnWab5dELks7FDNrRDKfIJCQA) – Pedro Mora Nov 06 '21 at 19:28
@PedroMora in linked example it is not clear what generics is used for – Aleksey L. Nov 07 '21 at 06:38
1

Let's say instead `prop: string` I have a method wich returns an `obj instanceof GenericType` – Pedro Mora Nov 07 '21 at 12:29
1

@PedroMora here's a workaround https://www.typescriptlang.org/play?#code/JYOwLgpgTgZghgYwgAgPoGUIBsYCUIzQQhIAmAPACoB8yA3sgNoAeAXMgM5hSgDmAuu0w58hKMTJVqAbmQBfAFBgAngAcUwvASIkIFGsgC8aTaJ2SDAMmT4EAeygUA5Kqh3VTgDTIAFAEojWhoFBVIIBCw4cWR7EC5kABIwiFUhbC0xCT1yOmBSVhAAVwBbACNoORkFLAgwZEiuM3FdI0Tk1QA6OA6AN2hlDqw7EF4OkAguPQ722QB6WZV1NJFtZqRquEbVrI7Xd38OvOR5xYh2IrLoIA – Aleksey L. Nov 07 '21 at 12:45

Typescript - Self reference with generic property

1 Answers1