Spring Reactor：发布者发出值时如何引发异常？ [英] Spring Reactor: How to throw an exception when publisher emit a value?

问题描述

我正在使用Reactor学习反应式编程，我想实现注册方案，在该方案中，用户可以将多个帐户分配给同一个人资料。但是，分配给配置文件的用户名和分配给帐户的电话必须唯一。

I'm learning reactive programming with Reactor and I want to implement registration scenario where a user can have many accounts assigned to the same profile. However the username assigned to the profile and the phone assigned to the account must be unique.

如下面的代码片段所示，如果满足以下条件，这种情况将很容易实现Reactor正在向操作员提供 switchIfNotEmpty 。

As you can see in the following snippet, this scenario will be easy to implement if Reactor was offering the operator switchIfNotEmpty.

public Mono<PersonalAccountResponse> createPersonalAccount(PersonalAccountRequest request) {
    return Mono
            .just(request.isAlreadyUser())
            .flatMap(isAlreadyUser ->  {
                if(isAlreadyUser){
                    return profileDao
                            .findByUsername(request.getUsername()) //
                            .switchIfEmpty(Mono.error(() -> new IllegalArgumentException("...")));
                }else{
                    return profileDao
                            .findByUsername(request.getUsername())
                            .switchIfEmpty(Mono.from(profileDao.save(profileData)))
                            .switchIfNotEmpty(Mono.error(() -> new IllegalArgumentException("...")));
                }
            })
            .map(profileData -> personalAccountMapper.toData(request))
            .flatMap(accountData -> personalAccountDao
                                            .retrieveByMobile(request.getMobileNumber())
                                            .switchIfEmpty(Mono.from(personalAccountDao.save(accountData)))
                                            .switchIfNotEmpty(Mono.error(() -> new IllegalArgumentException("..."))))
            .map(data ->  personalAccountMapper.toResponse(data, request.getUsername()));
}

如何在没有 switchIfNotEmpty的情况下实现此要求？

谢谢

推荐答案

发布者发出值时出现例外，可以使用对发出的值进行操作的多个运算符之一。

To propagate an exception when a publisher emits a value, you can use one of several operators that operate on emitted values.

一些示例：

fluxOrMono.flatMap(next -> Mono.error(new IllegalArgumentException()))

fluxOrMono.map(next -> { throw new IllegalArgumentException(); })

fluxOrMono.doOnNext(next -> { throw new IllegalArgumentException(); })

fluxOrMono.handle((next, sink) -> sink.error(new IllegalArgumentException()))

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