TypeORM tricks

typeorm_tricks.md

TypeORM tricks

Finding entity with with relation condition

There's a workaround for filtering based on relation fields for findOne()/find() methods that I've discovered recently. The problem with filtering related table fields only exists for ObjectLiteral-style where, while string conditions work perfectly.

Assume that we have two entities – User and Role, user belongs to one role, role has many users:

@Entity()
export class User {
  name: string;

  @ManyToOne(() => Role, role => role.users)
  role: Role;
}

@Entity()
export class Role {
  @OneToMany(() => User, user => user.role)
  users: User[];
}

Now we can call findOne()/find() methods of EntityManager or repository:

roleRepository.find({
  join: { alias: 'roles', innerJoin: { users: 'roles.users' } },
  where: qb => {
    qb.where({ // Filter Role fields
      a: 1,
      b: 2
    }).andWhere('users.name = :userName', { userName: 'John Doe' }); // Filter related field
  }
});

You can omit the join part if you've marked your relation as an eager one.

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