How do you implement a Unit of Work pattern to group database operations across repositories in NestJS?

Q: How do you implement a Unit of Work pattern to group database operations across repositories in NestJS?

// Unit of Work — wraps a transaction and exposes typed repositories @Injectable() export class UnitOfWork { constructor(private dataSource: DataSource) {} async execute ( work: (repos: { users: Repository ; orders: Repository ; products: Repository ; }) => Promise , ): Promise { return this.dataSource.transaction(async (manager: EntityManager) => work({ users: manager.getRepository(User), orders: manager.getRepository(Order), products: manager.getRepository(Product), }), ); } } // Service — uses UnitOfWork for complex multi-entity operations @Injectable() export class CheckoutService { constructor(private uow: UnitOfWork) {} async checkout(userId: number, cartItems: CartItem[]): Promise { return this.uow.execute(async ({ users, orders, products }) => { const user = await users.findOneOrFail({ where: { id: userId } }); const order = await orders.save(orders.create({ user, status: 'PENDING' })); for (const item of cartItems) { await products.decrement({ id: item.productId }, 'stock', item.qty); } user.lastOrderAt = new Date(); await users.save(user); return order; }); } } Groups all repositories under a single shared transaction without threading EntityManager manually. The work callback receives repository instances already bound to the transactional manager. Add new entity types to the repos parameter as the domain grows — no service changes required. All writes commit atomically or roll back together — no partial state is ever persisted. Services remain focused on business logic; transaction infrastructure is fully encapsulated in UnitOfWork.

Difficulty: 5/10

transaction management, repository pattern, dependency injection

Create a UnitOfWork service that wraps dataSource.transaction() and provides per-type repositories from the transactional EntityManager. The calling service receives a repos object containing all repositories bound to the same transaction, eliminating the need to manually thread EntityManager through every method call.

Unit of Work implementation and usage

Unit of Work pattern benefits:

1
Groups all repositories under a single shared transaction without threading EntityManager manually.

How do you implement a Unit of Work pattern to group database operations across repositories in NestJS?

Difficulty: 5/10

transaction management, repository pattern, dependency injection

Create a UnitOfWork service that wraps dataSource.transaction() and provides per-type repositories from the transactional EntityManager. The calling service receives a repos object containing all repositories bound to the same transaction, eliminating the need to manually thread EntityManager through every method call.

Unit of Work implementation and usage

Unit of Work pattern benefits:

1
Groups all repositories under a single shared transaction without threading EntityManager manually.

How do you implement a Unit of Work pattern to group database operations across repositories in NestJS?

How do you implement a Unit of Work pattern to group database operations across repositories in NestJS?

Scenario Questions

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