How i return Empty mono if the request doesn't return error using webClient-CodePudding

i want to know how return a empty Mono when i use webClient, i have this code and it works when the request return a user.

public User getUserByUsername(String username) {
            Mono<User> user = webClient.get().uri(uriBuilder -> uriBuilder
                    .path("localhost:8090/user"   "/getByUsername").queryParam("username", username).build())
                    .retrieve()
                    .bodyToMono(User.class);

            User userRet = user.block();
            return userRet;
        
    }

CodePudding user response：

First of all, don't use block() if you really want to take full advantage of using reactive stack. With it you are blocking the thread to wait for a response, don't do that. You must always handle Mono and Flux in your code instead. Something along the following lines:

public Mono<User> getUserByUsername(String username) {
    return webClient.get().uri(uriBuilder -> uriBuilder
            .path("localhost:8090/user"   "/getByUsername").queryParam("username", username).build())
            .retrieve()
            .bodyToMono(User.class);
}

You can then specify what you want to do if the response is 4XX or 5XX. Below the example for 5XX:

public Mono<User> getUserByUsername(String username) {
    return webClient.get().uri(uriBuilder -> uriBuilder
            .path("localhost:8090/user"   "/getByUsername").queryParam("username", username).build())
            .retrieve()
            .onStatus(HttpStatus::is5xxServerError, response -> Mono.empty())
            .bodyToMono(User.class);
}