Good day

Trying to deal with generics

There are 2 types

1. TUserInfo

type TUserInfo = {
   id: num,
   readonly fname: string,
   readonly lname: string
}

2. TBody

type TBody = {
   success: boolean,
   user?: any
}

Tell me how to pass any type to TBody (for example, TUserInfo). And user should have the same type instead of any. Thank you in advance

CodePudding user response：

I think it is better to use discriminated unions in this case:

export interface User {
    id: number,
    fname: string,
    lname: string
}

type Response<T> =
    | {
        success: true;
        user: T
    }
    | {
        success: false
    }

type Result = Response<User>

declare var result: Result

if (result.success) {
    result.user
} else {
    result.success // false
    result.user // error
}

I'd willing to bet that if success if false - user property should be ubdefined.

Result type is pretty popular monad. See Rust Result, F# Result

CodePudding user response：

In typescript, you can create interfaces.

export interface TUserInfo {
    id: number,
    fname: string,
    lname: string
}

export interface TBody {
    success: boolean,
    user?: TUserInfo
}

CodePudding user response：

Did so

type TBody<T> = {
       success: boolean;
       user?: T;
    }