user.service.ts

type IsolationOptions = {
  entityManager?: EntityManager<IDatabaseDriver<Connection>>;
  flush?: boolean;
};

@Injectable()
export class UsersService {
  constructor(
    private readonly _entityManager: EntityManager<IDatabaseDriver<Connection>>,
  ) {}

  public async create(
    options: UserEntityOptions,
    {
      entityManager = this._entityManager,
      flush = true,
    }: IsolationOptions = {},
  ): Promise<UserEntity> {
    const repo = this._getUserEntityRepository(entityManager);
    const password = await bcrypt.hash(options.password, BCRYPT_ROUNDS);
    const user = new UserEntity({ ...options, password });
    repo.persist(user);
    if (flush) {
      await entityManager.flush();
    }
    return user;
  }

  private _getUserEntityRepository(
    entityManager: EntityManager<IDatabaseDriver<Connection>> = this
      ._entityManager,
  ) {
    return entityManager.getRepository(UserEntity);
  }
}