Carry forward a Uni result?

[Stwissel]

Still getting my feet wet. I have code that needs to "carry forward" an interim result. Roughly like that:

Uni<CustomerProfile> uniCustomer = CustomerStore(someId);
uniCustomer.map(myCustomer -> PromoStore.getPromos())
.subscribe().with(promo -> sendPromo(myCustomer,promo), this::handleError);

Obviously that doesn't work. myCustomer is out of scope for sendPromo. So I hacked around it:

List<CustomerProfile> profiles = new ArrayList<>();
Uni<CustomerProfile> uniCustomer = CustomerStore(someId);
uniCustomer.map(myCustomer -> {
     profiles.add(myCustomer); 
     return PromoStore.getPromos();
})
.subscribe().with(promo -> sendPromo(profiles.get(0),promo), this::handleError);

But that doesn't feel right. What could I do instead?

[jponge]

One way to solve it is to rely on some external container data type as you did.

Another way is to create a data class to hold the values for the call to .getPromos() and myCustomer, so in the next step you have access to both (e.g., MyClass(List<CustomerProfiles>, CustomerProfile)).

There are also times where you can use a nested flatMap / concatMap / transformToUni so you can keep a value in scope, as in:

Uni.createFrom().item(123)
        .flatMap(base -> Uni.createFrom().item(List.of(base, base + 1, base + 2))
                .map(list -> Uni.createFrom().item(base + " -> " + list)))
        .subscribe().with(System.out::println);