TypeOrm - Custom Many to Many not pulling relation data

Question

because I don't want use cascade to update the join table and I want custom columns, I've created a custom many to many relationship. However when I query the relation it only provides the values in the join table and doesn't pull the relation data.

User

@Entity('user')
export class User {
  @PrimaryColumn()
  id: string;

  @OneToMany(
    () => UserArtistFollowing,
    (userArtistFollowing) => userArtistFollowing.user
  )
  following: UserArtistFollowing[];
}

Artist

@Entity('artist')
export class Artist {
  @PrimaryGeneratedColumn('uuid')
  id: string;

  @OneToMany(
    () => UserArtistFollowing,
    (userArtistFollowing) => userArtistFollowing.artist
  )
  usersFollowing: UserArtistFollowing[];

}

UserArtistFollowing

@Entity('userArtistFollowing')
export class UserArtistFollowing {
  @PrimaryGeneratedColumn('uuid')
  id: string;

  @Column()
  userId!: string;

  @Column()
  artistId!: string;

  @ManyToOne(
    () => User,
    (user) => user.following
  )
  user!: User;

  @ManyToOne(
    () => Artist,
    (artist) => artist.usersFollowing
  )
  artist!: Artist;

  @CreateDateColumn()
  createdAt!: Date;

  @UpdateDateColumn()
  updatedAt!: Date;
}

Query

    const user = await getManager()
      .getRepository(Models.User)
      .findOne({
        where: { id: id },
        relations: ['following'],
      });

So that query only provides the id, userId, artistId, but not the Artist array of objects (which is the data I need).

Thoughts?

Answer 1

After further testing, turns out you can use find -> relations with these kinds of custom many to many relationships. You just have to specify the relation in dotted notation for nested relations.

      const user = await getManager()
        .getRepository(Models.User)
        .findOne({
          where: { id },
          relations: [
// you have to specify the join table first (following) to retrieve the columns in the join table
            'following',
// then you use dotted notation to get the relation from the join table
            'following.artist',
// another example of a deeply nested relation
            'favourites',
            'favourites.song',
            'favourites.song.supportingArtists',
            'favourites.song.supportingArtists.artist',
          ],
        });

You can also use join with a nested leftJoinAndSelect, but its more tedious.

    const user = await getManager()
      .getRepository(Models.User)
      .findOne({
        where: { id },
        join: {
          alias: 'user',
          leftJoinAndSelect: {
            following: 'user.following',
            artists: 'following.artist',
          },
        },
      });

Here is the updated entities

UserArtistFollowing

@Entity('userArtistFollowing')
export class UserArtistFollowing {
  @PrimaryColumn()
  userId: string;

  @PrimaryColumn()
  artistId: string;

  @ManyToOne(
    () => User,
    (user) => user.following
  )
  user!: User;

  @ManyToOne(
    () => Artist,
    (artist) => artist.usersFollowing
  )
  artist!: Artist;

  @CreateDateColumn()
  createdAt!: Date;

  @UpdateDateColumn()
  updatedAt!: Date;
}

Artist

@Entity('artist')
export class Artist {
  @PrimaryGeneratedColumn('uuid')
  id: string;

  @OneToMany(
    () => UserArtistFollowing,
    (userArtistFollowing) => userArtistFollowing.artist
  )
  usersFollowing: UserArtistFollowing[];
}

User

@Entity('user')
export class User {
  @PrimaryColumn()
  id: string;

  @OneToMany(
    () => UserArtistFollowing,
    (userArtistFollowing) => userArtistFollowing.user
  )
  following: UserArtistFollowing[];
}