如何在 TypeScript 中嵌套枚举？

Question

假设我有一个这样的函数，但枚举参数有更多可能的值：

enum API{
    userDetails = "/api/user/details",
    userPosts = "/api/user/posts",
    userComments = "/api/user/comments",
    postDetails = "/api/post/details",
    postComments = "/api/post/comments"
    //...
};

function callAPI(endpoint: API/*, some more params*/){
    // some code to deal with the specified endpoint...
}

callAPI(API.userComments);

上面的代码工作正常，但我需要将枚举的许多值组合成一个有组织的层次结构，以使事情更有条理......例如，如果调用的语法会更好API 可以是callAPI(API.user.comments) 而不是callAPI(API.userComments)。

我尝试了以下尝试，但似乎没有一个被接受为打字稿的有效语法。

尝试 1

enum API{
    user = {
        details : "/api/user/details",
        userPorts : "/api/user/posts",
        userComments : "/api/user/comments"
    }
    post = {
        postDetails : "/api/post/details",
        postComments : "/api/post/comments"
    }
}

尝试 2

enum user {
    details = "/api/user/details",
    userPorts = "/api/user/posts",
    userComments = "/api/user/comments"
}
enum post {
    postDetails = "/api/post/details",
    postComments = "/api/post/comments"
}
enum API{
    user,
    post
}

尝试 3

enum user {
    details = "/api/user/details",
    userPorts = "/api/user/posts",
    userComments = "/api/user/comments"
}
enum post {
    postDetails = "/api/post/details",
    postComments = "/api/post/comments"
}
enum API{
    user = user,
    post = post
}

尝试 4

enum user {
    details = "/api/user/details",
    userPorts = "/api/user/posts",
    userComments = "/api/user/comments"
}
enum post {
    postDetails = "/api/post/details",
    postComments = "/api/post/comments"
}
enum API{
    user:user
    post:post
}

Answer 1

你可以把它包裹在 namespace:

namespace API{
    export enum User {
        details = "/api/user/details",
        posts = "/api/user/posts",
        comments = "/api/user/comments",
    }
    export enum Post {
        details = "/api/post/details",
        comments = "/api/post/comments",
    }
}

console.log(API.User.comments)
console.log(API.Post.details)

Answer 2

我的理解是枚举是不可能的——枚举成员的右侧可以是空值、数字、字符串或其他枚举值。 详情请见https://www.typescriptlang.org/docs/handbook/enums.html。

但是您可以使用普通对象轻松实现您想要的。

const API = {
  user: {
    details: "/api/user/details",
    posts: "/api/user/posts",
  },
  // ...
};

如果担心会被修改，可以使用Object.freeze。

如果您需要通过参数将整个 API 对象传递给函数，那么您也需要为其定义一个接口，否则自动完成和检查应该可以正常工作。

-------- 编辑

添加类型以备不时之需：

export type ApiRoutes<TRoute extends string> = { [key in TRoute]: string };

export interface MyApi {
  user: ApiRoutes<"details" | "posts" | "comments">;
  post: ApiRoutes<"details" | "comments">;
}