Typeorm how to get relations of relations - mysql

Question

I am getting the Object ChatRoomEntity with entitymanager.findOne method. The ChatRoomEntity has the variable messages which is a OneToMany - ManyToOne Relation. I have no problems to select that but how do I get the user which sent the message. Its a variable on MessageEntity with a OneToMany Relation.
So basically I want to select a room and all messages of it. But all messages should also have their values on fromUser.
I select the room like this:
this.entityManager.findOne(ChatRoomEntity, {where: {id: roomToJoin.id}, relations: ['activeUsers', 'messages']}).then(roomEntity => {
// some code
}
Here my entities:
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

We can load sub-relations by using 'relation.subrelation' within the relations array itself like this:
relations: ['relation1', 'relation2', 'relation2.subrelation1']
So for your case, instead of using join you can simply do something like this:
this.entityManager.findOne(ChatRoomEntity, {
where: {id: roomToJoin.id},
relations: ['activeUsers', 'messages', 'messages.fromUser'],
}).then(roomEntity => {
...
This is specified here: https://github.com/typeorm/typeorm/blob/master/docs/find-options.md#basic-options

Answer 2

Using QueryBuilder
await getRepository(UserEntity)
.createQueryBuilder('user')
.leftJoinAndSelect('user.profile', 'profile')
.leftJoinAndSelect('profile.images', 'images')
.getMany()
Using FindOptions
await getRepository(UserEntity).find({
relations: ['profile', 'profile.images']
})

Answer 3

Update v0.4.0
Typeorm is ditching findOne, you should use findOneBy for the queries without relations, and if you want relations, simply use find.
const users = await userRepository.find({
where: { /* conditions */ },
relations: { /* relations */ }
})
// users[0] if you want a first row

Answer 4

here is the #gradii/fedaco orm how to implement this feature.
use can use multi relations by method with
export class User extends Model {
#HasOneColumn({related: Profile})
profile;
}
export class Profile extends Model {
#HasOneColumn({related: Image})
image;
}
export class Image extends Model {
name;
}
eager load
User.createQuery().with('profile.image').get()
lazy load
const user = await User.createQuery().first();
const image await (await user.profile).image