I don't deal with the exact concept of Monad, but try to look at the form used by Java Optional from a Monad application perspective. Monad has a variety of applications and Optional is one of them (Optional are also called maybe monad). The terms ...
If we make java.util.Date object, basically log format is below. Sun May 08 18:03:23 KST 2022 Our team has an old system that is more than 10 years old so we are developing for renewal. The legacy program log format likes above. But We have to make s...
Variable s has string value. If I put that variable in Integer.valueOf method, I must encounter NumberFormatException. But It's not important. I just want to make exception. Let's see the below code. I can log variable s and exception e together usin...
This episode story is simple. If we receive response that is list type, we can use flatMapIterable operator(finally return type is Flux). Sometimes, I found the Mono<List<T>> type. public Flux<String> getData() { return this.webClient.get() ...
Let's imagine we received the WebClient response data and then binding to ResponseDto. Message value in ResponseDto can be null. public class ResponseDto { private String id; @Nullable private String message; public String getMessag...
Metric We have to know that It is different between WebClient level metric and reactor.netty level metric which is implementation of WebClient. At first, WebClient level metric is made by DefaultWebClientExchangeTagsProvider and is tagged in units of...
Change flatMap to map and onErrorResume to onErrorMap AS-IS Let's see the below code. I use clientResponse.createException().flatMap() and onErrorResume. However That is inefficient code. because flatMap unwrap and wrap to Mono.error again. onError...
1. When we don't need response body There are three options that can use when we don't need response body. releaseBody(), toBodilessEntity(), bodyToMono(Void.class) However the reactor-netty maintainer recommended only two method releaseBody(), toBod...
When we use exchangeToMono I explained the WebClient exchange operator in episode1 article. However exchange operator is deprecated so Instead of using exchange, we have to use exchangeToMono(or exchangeToFlux) 1) doOnSuccess and onErrorResume combin...