nestjs / TypeOrm database transaction

Question

Assuming we have 2 services, A and B. Service A has a function doing the following:

1. Validate the data
2. Call a service B function, that makes changes to

Answer 1

typeorm-transactional-cls-hooked uses CLS (Continuation Local Storage) to handle and propagate transactions between different repositories and service methods.

@Injectable()
export class PostService {
  constructor(
    private readonly authorRepository: AuthorRepository,
    private readonly postRepository: PostRepository,
  ) {}

  @Transactional() // will open a transaction if one doesn't already exist
  async createPost(authorUsername: string, message: string): Promise {
    const author = await this.authorRepository.create({ username: authorUsername });
    return this.postRepository.save({ message, author_id: author.id });
  }
}