node.js - 我如何存取 CASL 條件的巢狀屬性

我似乎無法使用條件規則訪問嵌套對象。我希望用戶能夠刪除文章，如果該文章的評論ID與用戶ID相同。這些只是一些用來測試的虛構類別...

這是我的程式碼：

import { defineAbility, AbilityBuilder } from '@casl/ability';

import { Ability, AbilityClass, ExtractSubjectType, InferSubjects } from '@casl/ability';

export class Article {
    static readonly modelName = "Article";
    static readonly __typename = "Article";
    constructor(  id: number,
        title: string,
        content: string,
        user: User,
        comment: Comment) {
            this.id = id
            this.title = title
            this.content = content
            this.user = user
            this.comment = comment
        }
  id: number
  title: string
  content: string
  user: User
  comment: Comment
}

export class User {
    static readonly modelName = "User"
    static readonly __typename = "User";
    constructor (id: number,
        name: string,
        comment: Comment) {
            this.id = id
            this.name = name
            this.comment = comment
        }
  id: number
  name: string
  comment: Comment
}

export class Comment {
    static readonly modelName = "Comment"
    static readonly __typename = "Comment";
  constructor(id: number,
    content: string,
    authorId: number) {
        this.id = id
        this.content = content
        this.authorId = authorId
    }
    id: number
  content: string
  authorId: number
}

type Action = 'create' | 'read' | 'update' | 'delete';
type Subjects = InferSubjects<typeof Article | typeof Comment| typeof User, true>;

export type AppAbility = Ability<[Action, Subjects]>;


export function createForUser(user: User) {
    const { can, cannot, build } = new AbilityBuilder<
      Ability<[Action, Subjects]>
    >(Ability as AbilityClass<AppAbility>);

    can('delete', Article, { comment: {id: user.comment.id}})

    return build({
      detectSubjectType: item => item.constructor as ExtractSubjectType<Subjects>
    });
  }

而我正在用它測試：

const comment = new Comment(0, 'a', 0)
const user = new User(1, 'sd', comment);
const article = new Article(2, 'sd', 'asd', user, comment)
const ability = createForUser(user);

console.log(ability.can('delete', article))// false

我在某處看到我需要這麼做：can('delete', Article, { 'comment.id': user.comment.id})，但當我這麼做時，它顯示『物件字面值只能指定已知屬性，而 'comment.id' 在類型 'string[]' 中不存在』

答案＃1

你可以在 https://casl.js.org/v5/en/advanced/typescript 上找到「使用點記法的嵌套欄位」部分，這會很有用。簡而言之，當你在 TypeScript 中使用點記法來定義條件時，你需要創建一個自訂類型：

type FlatArticle = Article & {
  'comment.id': Article['comment']['id']
};

can<FlatArticle>('read', Article, { 'comment.id': 1 });

答案＃2

最後是這樣解決的：

export enum Action {
    Manage = 'manage',
    Create = 'create',
    Read   = 'read',
    Update = 'update',
    Delete = 'delete',
}

export type Subject = InferSubjects<typeof Article | 
                                     typeof Comment | 
                                     typeof User | 
                                     'all';

export type AppAbility = PureAbility<[Action, Subject]>;
export const AppAbility = Ability as AbilityClass<AppAbility>;

然後像這樣定義規則：

createForUser(user: User) {
  const { can, cannot, build } = new AbilityBuilder(AppAbility);
  
  
  can(Action.Read, Article, { 'comment.id': 1 });

    
  return build({
    detectSubjectType: item => item.constructor as ExtractSubjectType<Subject>
  });
}