如何访问 CASL 条件的嵌套属性

Question

我似乎无法使用条件规则访问嵌套对象。 如果文章的评论与用户具有相同的 ID，我希望用户有权删除文章。 这些只是一些用来测试的编造类...

这是我的代码：

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>
    });
  }

我正在测试它：

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

我在某处看到我需要做这样的事情： can('delete', Article, { 'comment.id': user.comment.id}) 但是当我说'对象文字可能只指定已知属性，''comment.id''在'string []'类型中不存在

Answer 1

您可以在https://casl.js.org/v5/en/advanced/typescript 上找到有用的“带点表示法的嵌套字段”部分。总之，当你使用 for 表示法和 typescript 一起定义条件时，你需要创建一个自定义类型：

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

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

Answer 2

最终这样解决：

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>;

然后像这样定义规则：

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>
  });
}