flatMap reuse response from reactive call

Currently, I have a question, something like this:

WebClient.call(...)
       .flatMap(user -> webclient.call("host1",user.getId/*obj request*/);})//assume this return X.class
  (*)  .flatMap(x -> webclient.call("host2",user.getName/*obj request*/))//"x" is not used here, i want reuse object "user" but was compiled error, // assume this return Y.class
       .map(x -> webclient.call(...))// "x" is used here

User

Class User {
    string id;
    string name;
}

X

Class X {
    string deviceNo;
}

Y

Class Y {
    Boolean isCorrect;
}

The question is how do I reuse correctly the “user” and the “x” response from the previous call?

Here are my solutions for marked(*) place:

1. nested flatMap(), then can thenReturn(user) for next map().

Any issue with the scope of a variable(user) when I build a chain(nested flatMap…) like this so far?

       .flatMap(user -> { 
              return webclient.call("host1",user.getId/*obj request*/))
              .flatMap(x -> webclient.call("host2",user.getName/*obj request*/) //this consider as a side effect?
              .thenReturn(x));} still return "x"
       .map(x -> webclient.call(...))// "x" is used here 

2. keep response by wrapping it in an object using map (i don’t want to use this solution)

       .flatMap(user -> {
               return webclient.call("host1",user.getId/*obj request*/).map(x-> new X1(x, user)}))
       .flatMap(x1 -> webclient.call("host2", X1.GETUSER.GETNAME /*obj request*/).map(y -> new Y1(x1, y)}))
       .map(y1 -> webclient.call("host3",Y1.GETX1.X...))// "x" is used here 

X1, wrap x and user

Class X1 {
    public X1(x, user){}//contructor

    X x;
    User user
}

any idea, please help to review/advice Thank you

Answer

This question is very opinionated.

i would personally use a zipWith operator which merges the results of 2 monos into a tuple.

WebClient.call(...)
    .flatMap(user -> webclient.call("host1",user.getId())
            .zipWith(webclient.call("host2",user.getName()))
    .flatMap(values -> {
        var x = values.getT1();
        var y = values.getT2(),
    })