nestjs / TypeOrm database transaction
Here is how I solved it since I needed to use a pessimistic lock.
I feel it is the "Nest" way of doing things as you can simply ask NestJS
to inject an instance of a Typeorm Connection
and you're good to go.
@Injectable()
class MyService {
// 1. Inject the Typeorm Connection
constructor(@InjectConnection() private connection: Connection) { }
async findById(id: number): Promise<Thing> {
return new Promise(resolve => {
// 2. Do your business logic
this.connection.transaction(async entityManager => {
resolve(
await entityManager.findOne(Thing, id, {
lock: { mode: 'pessimistic_write' },
}),
);
});
});
}
}
Simply place whatever other logic you need inside the .transaction
block and you're good to go.
NOTE: You MUST use the entityManager
provided by the .transaction
method or else it will not work.
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.