TypeORM:如何计算关系并将其转换为布尔值

// User.ts
import { Entity, PrimaryGeneratedColumn, Column, ManyToMany, JoinTable } from "typeorm";
import { Role } from "./Role";

@Entity()
export class User {
  @PrimaryGeneratedColumn()
  id: number;

  @Column()
  name: string;

  @ManyToMany(type => Role)
  @JoinTable()
  roles: Role[];
}

// Role.ts
import { Entity, PrimaryGeneratedColumn, Column, ManyToMany } from "typeorm";
import { User } from "./User";

@Entity()
export class Role {
  @PrimaryGeneratedColumn()
  id: number;

  @Column()
  name: string;

  @ManyToMany(type => User)
  users: User[];
}

// 在某个地方，比如服务类中
import { getRepository } from "typeorm";

// 检查用户是否具有某个角色
async function hasRole(userId: number, roleName: string): Promise<boolean> {
  const userRepository = getRepository(User);
  const user = await userRepository.findOne(userId, { relations: ["roles"] });
  
  if (user) {
    const roleExists = user.roles.some(role => role.name === roleName);
    return roleExists;
  }
  
  return false;
}