如何强制某些枚举类型的接口键？

Question

考虑此界面：

export interface Vehicle<E> {
 [key: E]: {
   title: string
 }
}

以及这些枚举：

export enum EuropeanCars {
  MAKE_A = 1
  MAKE_B = 2
}

export enum AmericanCars {
  MAKE_A = 3
  MAKE_B = 4
}

我想构建对象并强迫它们具有枚举类型的键：

export const AmericanCarDetails: Vehicle<EuropeanCars> = {
...
}

当前，我在界面中遇到此错误：key:E --- An index signature parameter type must be either 'string' or 'number'.

Answer 1

您可以使用mapped type代替界面：

export type Vehicle<E extends PropertyKey> = {
    [key in E]: {
        title: string
    }
}

export enum EuropeanCars {
    MAKE_A = 1,
    MAKE_B = 2
}

export enum AmericanCars {
    MAKE_A = 3,
    MAKE_B = 4
}

export const AmericanCarDetails: Vehicle<AmericanCars> = {
    [AmericanCars.MAKE_A]: { title: 'foo' },
    [AmericanCars.MAKE_B]: { title: 'foo' },
}

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