typeORM 多对多关系不同情况的处理

本文以RBAC权限管理中的用户和角色举例，两个实体存在多对多的关系，一个用户拥有多个角色，一个角色属于多个用户。typeorm的中文文档没有对自定义中间表的说明，发现英文有相关说明，但示例代码貌似有问题。

一、中间表有自定义字段的处理

在用户user和role实体之外，新建一个roleUse的实体（记录用户和角色的关联关系），如此本来是多对多的关系，变成了user和role与roleUser二组一对多的关系，这样虽然会多定义一个实体，但好处是可以中间表可以扩展定义其它额外的数据

用户实体 user.entity.ts

import { Entity, Column, Index, ManyToMany, JoinColumn, OneToMany, JoinTable, PrimaryGeneratedColumn, CreateDateColumn, UpdateDateColumn } from 'typeorm';
import { Role } from '../../admin/role/role.entity';
import { UserRole } from '../../admin/role/roleUser.entity';

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

    @Column({ length: 100 })
    @Index({ unique: true })
    name: string;

    @OneToMany(type => UserRole, userRole => userRole.user)
    userRoles: UserRole[];
}

角色实体role.entity.ts

import { Entity, Column, ManyToMany, OneToMany, JoinTable, JoinColumn } from 'typeorm';
import { BaseEntity } from '../../../common/base/base.entity';
import { UserRole } from './roleUser.entity';

@Entity('role')
export class Role extends BaseEntity {
    @Column({ length: 100 })
    role_name: string;

    @OneToMany(type => UserRole, userRole => userRole.role)
    userRoles: UserRole[];

}

中间表实体 roleUser.entity.ts (主健)

import { Entity, PrimaryGeneratedColumn, JoinColumn, Column, CreateDateColumn, UpdateDateColumn, ManyToOne } from 'typeorm';
import { BaseEntity } from '../../../common/base/base.entity';
import { User } from '../../web/user/user.entity';
import { Role } from './role.entity';

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

    @CreateDateColumn()
    created_time: Date;

    @UpdateDateColumn()
    updated_time: Date;

    @ManyToOne(type => User, user => user.userRoles)
    @JoinColumn({name: 'user_id'})
    user: User;

    @ManyToOne(type => Role, role => role.userRoles)
    @JoinColumn({name: 'role_id'})
    role: Role;
}

中间表定义roleUser.entity.ts(复合主键)

import { Entity, PrimaryGeneratedColumn, JoinColumn, Column, CreateDateColumn, UpdateDateColumn, ManyToOne } from 'typeorm';
import { BaseEntity } from '../../../common/base/base.entity';
import { User } from '../../web/user/user.entity';
import { Role } from './role.entity';

@Entity()
export class UserRole {

    @CreateDateColumn()
    created_time: Date;

    @UpdateDateColumn()
    updated_time: Date;

    @ManyToOne(type => User, user => user.userRoles, { primary: true })
    @JoinColumn({name: 'user_id'})
    user: User;

    @ManyToOne(type => Role, role => role.userRoles, { primary: true })
    @JoinColumn({name: 'role_id'})
    role: Role;
}

　　

二、无中间表的多对多实体定义，又分为单向和双向，单向是仅在一侧与关系装饰器的关系， 双向是与关系两侧的装饰者的关系。具体官网文档：https://typeorm.io/#/relations，此处主要讲双向

角色实体　　

import { Entity, Column, ManyToMany, OneToMany, JoinTable, JoinColumn } from 'typeorm';
import { BaseEntity } from '../../../common/base/base.entity';
import { User } from '../../web/user/user.entity';

@Entity('role')
export class Role extends BaseEntity {
    @Column({ length: 100 })
    role_name: string;

    @Column({ length: 100 })
    remark: string;

    // 无中间实体表的配置
    @ManyToMany(type => User, user => user.roles, { cascade: true })
    users: User[];

}

用户实体

import { Entity, Column, Index, ManyToMany, JoinColumn, OneToMany, JoinTable, PrimaryGeneratedColumn, CreateDateColumn, UpdateDateColumn } from 'typeorm';
import { Role } from '../../admin/role/role.entity';

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

    @Column({ length: 100 })
    @Index({ unique: true })
    name: string;

    // 无中间实体表的配置
    @ManyToMany(type => Role, role => role.users)
    @JoinTable({
        name: 'user_role',
        joinColumns: [
            {name: 'user_id'}
        ],
        inverseJoinColumns: [
            {name: 'role_id'}
        ]
    })
    // 下面的定义也能实现
    //   @JoinTable({
    //     name: 'user_role',
    //     joinColumn: { name: 'user_id' },
    //     inverseJoinColumn: { name: 'role_id' },
    //   })
    roles: Role[];

}