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

Many solutions are available, they should all be based on SQL transaction management.

Personally I feel that the simplest way to achieve that is to use the same EntityManager instance when you execute code on your database. Then you can use something like:

getConnection().transaction(entityManager -> {
    service1.doStuff1(entityManager);
    service2.doStuff2(entityManager);
});

You can spawn a QueryRunner from an EntityManager instance that will be wrapped in the same transaction in case you execute raw SQL outside ORM operations. You need also to spawn Repository instances from EntityManager as well or they will execute code outside the main transaction.