Async Disposable

Joist’s EntityManager can be used with the new using keyword in TypeScript 5.2, to auto-flush changes to the database.

For example, in a method that creates an EntityManager:

async function performWork() {
  // Create an EntityManager w/your context & driver
  await using em = new EntityManager({}, driver);
  // Load an entity
  const a1 = await em.load(Author, "a:1");
  // Make any mutations
  a1.firstName = "a2";
  // That's it; `em.flush` will be called automatically
}

Note that the em.flush method can fail if any validation rules are invalid, or any errors occur while running hooks, in which case the caller of performWork would get a rejected promise.

Caution

As a disclaimer, the using statement is new, so we’re not 100% sure if it’s usage will end up being idiomatic or not.

For example, it’s common to do an explicit em.flush to ensure changes are committed to the database, any reactivity within the domain model has been executed, and only then build out a return value, i.e. a GraphQL result or REST response payload.

If you build a GraphQL result or REST payload before executing em.flush, you risk building it based on values that will be changed by hooks & derived values, so just keep that in mind.

The best practice is to ensure em.flush is ran before creating response values.