RXSwift 链接观察者并捕获错误答案

【问题标题】：RXSwift chaining observers and catch errorsRXSwift 链接观察者并捕获错误
【发布时间】：2020-06-17 19:09:19
【问题描述】：

我有一些代码应该在某些可观察操作完成时进行监听，但我无法以最佳方式编写它。

重要的是最终订阅的结果是事件，并且 updateEvent 最后运行。

这是我的代码：

/// Update Event
///
/// Updates an event and invites or removes any members from the event before updating the actual event information. This ensures newly updated event to contain the updated list of attendes
///
/// - Parameters:
///   - event: The event to update
///   - group: The group that the event belongs to
///   - newMembers: A list of new group members that should be invited to the invited
///   - removeMembers: A list of event attendees that should be removed from the event
func updateEvent(_ event: EventModel, _ group: GroupModel, newMembers: [MemberModel], removeMembers: [AttendanceModel]) {

    let updateEventObserver = self.repository.updateEvent(group, event)
    var memberObservers: [Observable<AttendanceModel>] = []

    if newMembers.count > 0 {
        memberObservers.append(contentsOf: newMembers.map { (member) in
            return self.repository.inviteToEvent(member: member, event: event, group: group)
        })
    }

    if removeMembers.count > 0 {
        memberObservers.append(contentsOf: removeMembers.map { (member) in
            return self.repository.removeFromEvent(member: member, event: event, group: group)
        })
    }

    if memberObservers.count > 0 {

        Observable
            .zip(memberObservers)
            .subscribe(onNext: { (_) in
                updateEventObserver
                    .subscribe(onNext: { event in
                        self.presenter.eventSuccessfullyUpdated(event)
                    }, onError: { error in
                        self.presenter.failedWithError(error)
                    }).disposed(by: self.disposeBag)
            }, onError: { (error) in
                self.presenter.failedWithError(error)
            }).disposed(by: self.disposeBag)
    } else {
        updateEventObserver
            .subscribe(onNext: { event in
                self.presenter.eventSuccessfullyUpdated(event)
            }, onError: { error in
                self.presenter.failedWithError(error)
            }).disposed(by: self.disposeBag)
    }

}

我认为我的代码“丑陋”，我觉得有更好的方法。谢谢！

【问题讨论】：

标签： swift rx-swift

【解决方案1】：

嗯，这有点干净：

func updateEvent(_ event: EventModel, _ group: GroupModel, newMembers: [MemberModel], removeMembers: [AttendanceModel]) {

    let invitedResults = newMembers
        .compactMap { [repository] member in
            repository?.inviteToEvent(member: member, event: event, group: group)
        }

    let removedResults = removeMembers
        .compactMap { [repository] member in
            repository?.removeFromEvent(member: member, event: event, group: group)
        }

    Observable.zip(invitedResults + removedResults)
        .flatMap { [repository] _ in repository?.updateEvent(group, event) ?? .empty() }
        .subscribe(
            onNext: { [presenter] event in
                presenter?.eventSuccessfullyUpdated(event)
            },
            onError: { [presenter] error in
                presenter?.failedWithError(error)
            }
        )
        .disposed(by: disposeBag)
}

它至少避免了捕获自我并进行保留循环。但是，如果任何邀请或删除错误可能会使您的系统处于无效状态...

【讨论】：

嘿，谢谢！如果邀请或删除失败，是否无法捕获错误并停止序列？
是的，这是默认行为，这就是问题所在。例如，如果前三个邀请成功但第四个失败，则不会调用 updateEvent 并且任何其他邀请/删除都将取消（由于抛出的错误。）您的服务器会知道该怎么做吗？情况？
谢谢。我喜欢你的回答，我已经看了好几遍了。