CODEWITHSUNDEEP
reactive-programmingspring-webfluxproject-reactorreactor-netty
user1578872
user1578872

Reputation: 9088

Reactive programming - With default and exception handling

I am trying to find the best approach for default and error handling with reactive.

This is a working code.

public Mono<ServerResponse> retrieveById(ServerRequest request) {
        final String id = request.pathVariable("ID");
        return context.retrieveUser().flatMap(usr -> {
            return repository.findByApptId(Long.parseLong(id), usr.getOrgId()).flatMap(appt -> {
                return ServerResponse.ok().contentType(APPLICATION_JSON).bodyValue(appt);
            });
        });
    }

I am trying to add default and error handling.

For default,

return context.retrieveUser().flatMap(usr -> {
            return repository.findByApptId(Long.parseLong(apptId), usr.getOrgId()).flatMap(appt -> {
                return ServerResponse.ok().contentType(APPLICATION_JSON).bodyValue(appt);
            }).defaultIfEmpty(ServerResponse.notFound().build());

The above default add gives error.

The method defaultIfEmpty(ServerResponse) in the type Mono is not applicable for the arguments
(Mono)

Same error with onErrorReturn as well.

Upvotes: 0

Views: 975

Answers (1)

Toerktumlare
Toerktumlare

Reputation: 14820

Mono#defaultIfEmpty takes an item T and returns a Mono<T>. Which means that if you give it a String it will return a Mono<String>.

You are giving it ServerResponse.notFound().build() which returns a Mono<ServerResponse> which won’t work since it would give Mono<Mono<ServerResponse>>.

What you are looking for is Mono#switchIfEmpty which switches producer (Mono) to another producer if the previous one turned out empty.

Upvotes: 2

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