Modify type signature for `ConfigService.get()` so that types are automatically inferred about config HOT 8 CLOSED

@kamilmysliwiec I'm struggling to get automatic return types to function. Could it have been possible that the lack of return type inference is related to #956?

Would love to drop the constant { infer: true } on every call if possible.

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Makes total sense. Let me mark this issue as blocked for now. We'll wait till TS +4.1 is released

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You can use [email protected] in the PR. We'll wait some time to make sure it's stable and then, publish a new major version of the package (to avoid introducing breaking changes in minor/patch releases).

from config.

Would you like to create a PR for this feature?

from config.

Hey @kamilmysliwiec, I was looking at the implementation in the repo and I realized that it's possible to pass a dot-path, if you're loading config from a custom provider and not just process.env.

Typing dot-paths will be possible in TS +4.1 with this PR:

microsoft/TypeScript#40336

type PropType<T, Path extends string> =
    string extends Path ? unknown :
    Path extends keyof T ? T[Path] :
    Path extends `${infer K}.${infer R}` ? K extends keyof T ? PropType<T[K], R> : unknown :
    unknown;

declare function getPropValue<T, P extends string>(obj: T, path: P): PropType<T, P>;
declare const s: string;

const obj = { a: { b: {c: 42, d: 'hello' }}};
getPropValue(obj, 'a');  // { b: {c: number, d: string } }
getPropValue(obj, 'a.b');  // {c: number, d: string }
getPropValue(obj, 'a.b.d');  // string
getPropValue(obj, 'a.b.x');  // unknown
getPropValue(obj, s);  // unknown

But currently, I think the limitations of TS are that the types for nested access can only be inferred if the argument is either an array or multiple variables, IE:

get(obj, ['user', 'email'])
get(obj, 'user', 'email')

So this might have to wait a bit unfortunately =/

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@GavinRay97 TS4 is already available. Would you like to take a look at this?

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Yeah I believe it should be possible to implement this now, due to:
https://devblogs.microsoft.com/typescript/announcing-typescript-4-1-beta/

I think the only requirement would be to set TS version to 4.1-beta and then later 4.1 in package.json to ensure the type doesn't break for other people, right?

from config.

Let's track this here #492

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