Getting multiple Mono objects with reactive Mongo queries - spring

Question

I'm using the webflux framework for spring boot, the behavior I'm trying to implement is creating a new customer in the database, if it does not already exist (throw an exception if it does)
and also maintain another country code database (if the new customer is from a new country, add to the database, if the country is already saved, use the old information)
This is the function in the service :
public Mono<Customer> createNewCustomer(Customer customer) {
if(!customer.isValid()) {
return Mono.error(new BadRequestException("Bad email or birthdate format"));
}
Mono<Customer> customerFromDB = customerDB.findByEmail(customer.getEmail());
Mono<Country> countryFromDB = countryDB.findByCountryCode(customer.getCountryCode());
Mono<Customer> c = customerFromDB.zipWith(countryFromDB).doOnSuccess(new Consumer<Tuple2<Customer, Country>>() {
#Override
public void accept(Tuple2<Customer, Country> t) {
System.err.println("tuple " + t);
if(t == null) {
countryDB.save(new Country(customer.getCountryCode(), customer.getCountryName())).subscribe();
customerDB.save(customer).subscribe();
return;
}
Customer cus = t.getT1();
Country country = t.getT2();
if(cus != null) {
throw new CustomerAlreadyExistsException();
}
if(country == null) {
countryDB.save(new Country(customer.getCountryCode(), customer.getCountryName())).subscribe();
}
else {
customer.setCountryName(country.getCountryName());
}
customerDB.save(customer).subscribe();
}
}).thenReturn(customer);
return c;
}
My problem is, the tuple returns null if either country or customer are not found, while I need to know about them separately if they exist or not, so that I can save to the database correctly.
country == null is never true
I also tried to use customerFromDB.block() to get the actual value but I receive an error that it's not supported, so I guess that's not the way
Is there anyway to do two queries to get their values?

Answer 1

Solved it with the following solution:
public Mono<Customer> createNewCustomer(Customer customer) {
if(!customer.isValid()) {
return Mono.error(new BadRequestException("Bad email or birthdate format"));
}
return customerDB.findByEmail(customer.getEmail())
.defaultIfEmpty(new Customer("empty", "", "", "", "", ""))
.flatMap(cu -> {
if(!cu.getEmail().equals("empty")) {
return Mono.error(new CustomerAlreadyExistsException());
}
return countryDB.findByCountryCode(customer.getCountryCode())
.defaultIfEmpty(new Country(customer.getCountryCode(), customer.getCountryName()))
.flatMap(country -> {
customer.setCountryName(country.getCountryName());
customerDB.save(customer).subscribe();
countryDB.save(country).subscribe();
return Mono.just(customer);});
});
}
Instead of doing both queries simulatneaously, I queried for one result and then queries for the next, I think this is the reactive way of doing it, but I'm open for corrections.