Typescript ：从可选列表中输入一个必需的属性

发布于10月03日

我有可选属性列表的接口.

export interface OptionalIds {
  entityA_Id?: number;
  entityB_Id?: number;
  entityC_Id?: number;
}

我有一个要求，那就是定义其中的EXACTLY个.大概是这样的:

export interface RequiredBId {
  entityA_Id?: undefined;
  entityB_Id: number;
  entityC_Id?: undefined;
}

export interface RequiredCId {
  entityA_Id?: undefined;
  entityB_Id?: undefined;
  entityC_Id: number;
}

export interface OptionalIds {
  entityA_Id?: number;
  entityB_Id?: number;
  entityC_Id?: number;
}

export type RestrictedOptionalIds = OptionalIds & (RequiredAId | RequiredBId | RequiredCId)

The question is:有没有其他方法可以在没有奇怪 struct 的情况下实现所描述的行为？

更新答案

感谢这篇RequireOnlyOne:https://stackoverflow.com/a/49725198/4529555的帖子

type RequireOnlyOne<T, Keys extends keyof T = keyof T> =
    Pick<T, Exclude<keyof T, Keys>>
    & {
        [K in Keys]-?:
            Required<Pick<T, K>>
            & Partial<Record<Exclude<Keys, K>, undefined>>
    }[Keys]

export interface OptionalIds {
  entityA_Id?: number;
  entityB_Id?: number;
  entityC_Id?: number;
}

const exampleA: RequireOnlyOne<OptionalIds> = {
  entityA_Id: 1
}
const exampleB: RequireOnlyOne<OptionalIds> = {
  entityB_Id: 1
}

const exampleC: RequireOnlyOne<OptionalIds> = {
  entityC_Id: 1
}

// Error
const exampleMultiple: RequireOnlyOne<OptionalIds> = {
  entityA_Id: 1,
  entityB_Id: 2,
}

// Error: {} not assignable to RequireAtLeastOne<OptionalIds, keyof OptionalIds>
const exampleTsError: RequireOnlyOne<OptionalIds> = {

}

原始答案

感谢这篇RequireAtLeastOne:https://stackoverflow.com/a/49725198/4529555的帖子

type RequireAtLeastOne<T, Keys extends keyof T = keyof T> =
    Pick<T, Exclude<keyof T, Keys>> 
    & {
        [K in Keys]-?: Required<Pick<T, K>> & Partial<Pick<T, Exclude<Keys, K>>>
    }[Keys]

export interface OptionalIds {
  entityA_Id?: number;
  entityB_Id?: number;
  entityC_Id?: number;
}

const exampleA: RequireAtLeastOne<OptionalIds> = {
  entityA_Id: 1
}
const exampleB: RequireAtLeastOne<OptionalIds> = {
  entityB_Id: 1
}

const exampleC: RequireAtLeastOne<OptionalIds> = {
  entityC_Id: 1
}

const exampleMultiple: RequireAtLeastOne<OptionalIds> = {
  entityA_Id: 1,
  entityB_Id: 2
}

// Error: {} not assignable to RequireAtLeastOne<OptionalIds, keyof OptionalIds>
const exampleTsError: RequireAtLeastOne<OptionalIds> = {

}