CODEWITHSUNDEEP
javareactive-programmingspring-webfluxspring-webclient
diwakarb
diwakarb

Reputation: 561

parallel calls to upstream service with request context

I am a newbie in spring web flux.

I have an upstream service that doesn't supports batch calls, hence I'll have to call it multiple times for each object in my array. I also need instance of request parameters because the service doesn't return these attributes in it's response.

For example, This is the response I'll be sending to our clients

class Person {
  int id;
  String name;
  int phoneNo;
}

and I have list of ids only

List<Integer> lstIds

Also for each person the api response is

{
   "name": "name",
   "phoneNo": 2222222222
}

Notice, there's no id field in the response hence, I'd need request parameter to map the request with response.

I have a method named createRequestFromIdWillReturnMono(int id) that takes the integer id and returns the web client Mono as response.

What I've tried so far

List<Person> response = new ArrayList<Person>();
List<Integer> lstInt = IntStream.rangeClosed(0, 10).boxed().collect(Collectors.toList());
Flux
     .fromIterable(lstInt)
     .flatMap(i -> createRequestFromIdWillReturnMono(i)
                       .map(personResponse -> response.add(new Person(i, personResponse))));
return response;

But this code only runs the response.add call once, even though it calls the createRequestFromIdWillReturnMono 10 times.

How should I fix this?

Upvotes: 1

Views: 379

Answers (1)

Toerktumlare
Toerktumlare

Reputation: 14712

You dont need the list, you can either use collectList and return a list. Or you return the Flux<Person> to the client, which is a stream.

Mono<List<Persons>> personsMono = Flux.fromIterable(lstInt)
     .flatMap(i -> createRequestFromIdWillReturnMono(i))
     .map(personResponse -> new Person(i,personResponse))
     .collectList();

Something like this, im not at a computer now so cant ensure it compiles, but you should understand.

Upvotes: 1

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