Spring Reactor not working on handle operation while DB fetch - spring-webflux

Question

I'm using spring reactor. The code below is :
public Mono<ResponseEntity<SignUpResponse>> createSignUpForUser(SignUpRequest signUpRequest) {
return Mono.just(signUpRequest)
.map(sign -> {
Mono<UserDetailsEntity> userDetailsEntityMono = userDetailsRepository.findByPhoneNumber(sign.getMobileNumber());
userDetailsEntityMono.handle((user, sink) -> {
if (user != null) {
sink.error(new RuntimeException("Phone number already registered"));
}
});
return functionUserDetails.apply(sign);
})
.flatMap(userDetailsRepository::save)
.map(functionUser)
.flatMap(userRepository::save)
.map(usr -> ResponseEntity.ok(functionSignUpRes.apply(usr)))
.defaultIfEmpty(ResponseEntity.notFound().build())
.log();
}
Here the findByPhoneNumber(sign.getMobileNumber()) DB call is not working (the error is not throwing). The Rest of the operations are working and returning the response. Am i doing anything wrongly ? help me to fix this issue.

Answer 1

I think you need to rewrite your code a bit
public Mono<ResponseEntity<SignUpResponse>> createSignUpForUser(SignUpRequest signUpRequest) {
return userDetailsRepository.findByPhoneNumber(sign.getMobileNumber())
.flatMap(__ -> Mono.error(new RuntimeException("Phone number already registered")))
.switchIfEmpty(userDetailsRepository.save(functionUserDetails.apply(sign)))
.map(functionUser)
.flatMap(userRepository::save)
.map(usr -> ResponseEntity.ok(functionSignUpRes.apply(usr)))
.defaultIfEmpty(ResponseEntity.notFound().build())
.log()
;
}
Idea is that if you find that number then it should error, if result is empty then you would need to insert it so we need to use switch if empty