Question

我正在使用entitymanager.findOne方法获取对象ChatRoomEntity。 ChatRoomEntity具有变量messages，该变量为OneToMany-ManyToOne关系。我选择它没有问题，但是如何获得发送邮件的用户。它是MessageEntity上具有OneToMany关系的变量。

因此，基本上我想选择一个房间及其所有消息。但所有消息也应在fromUser上具有其值。我选择这样的房间：

this.entityManager.findOne(ChatRoomEntity, {where: {id: roomToJoin.id}, relations: ['activeUsers', 'messages']}).then(roomEntity => {
// some code
}

这是我的实体：

UserEntity


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

  @CreateDateColumn()
  registrationDate: Date;

  @ManyToMany(type => ChatRoomEntity, room => room.activeUsers, {cascade: true})
  @JoinTable()
  activeChatRooms: ChatRoomEntity[];

  @OneToMany(type => ChatRoomMessageEntity, msg => msg.fromUser)
  chatRoomMessages: ChatRoomMessageEntity[];
}

ChatRoomEntity

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

  @Column('varchar', {nullable: true})
  title: string;

  @OneToMany(type => ChatRoomMessageEntity, chatrmsg => chatrmsg.chatRoom)
  messages: ChatRoomMessageEntity[];

  @ManyToMany(type => UserEntity, user => user.activeChatRooms)
  activeUsers: UserEntity[];

}

ChatRoomMessageEntity

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

  @Column('varchar', {nullable: true})
  message: string;

  @CreateDateColumn()
  creationDate: Date;

  @ManyToOne(type => UserEntity, user => user.chatRoomMessages)
  fromUser: UserEntity;

  @ManyToOne(type => ChatRoomEntity, chatRoom => chatRoom.messages)
  chatRoom: ChatRoomEntity;

}

Answer 1

我们可以通过在'relation.subrelation'数组本身中使用relations来加载子关系，如下所示：

relations: ['relation1', 'relation2', 'relation2.subrelation1']

因此，对于您的情况，无需使用join即可执行以下操作：

this.entityManager.findOne(ChatRoomEntity, {
        where: {id: roomToJoin.id},
        relations: ['activeUsers', 'messages', 'messages.fromUser'],
      }).then(roomEntity => {
...

在此处指定：https://github.com/typeorm/typeorm/blob/master/docs/find-options.md#basic-options

Answer 2

使用QueryBuilder

await getRepository(Entity)
   .createQueryBuilder('user')
   .leftJoinAndSelect('user.photo', 'photo')
   .leftJoinAndSelect('photo.photometa', 'photometa')
   .getMany()

Answer 3

好的，解决方案很简单。为了得到我需要的东西，我只是使用了这样的联接：

this.entityManager.findOne(ChatRoomEntity, {
        where: {id: roomToJoin.id},
        relations: ['activeUsers', 'messages'],
        join: {
          alias: 'cr', innerJoinAndSelect: {
            messages: 'cr.messages',
            users: 'messages.fromUser'
          }
        }
      }).then(roomEntity => {
...

Typeorm如何获得关系

3 个答案:

使用QueryBuilder