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Rxjava:可能是带有completable的flatmap

rx-java java

PerrierCitror · 技术社区 · 7 年前

我使用一个带有两个函数的外部API,一个返回 Maybe Completable (见下面的代码)。我希望函数“saveUser()”返回 doOnSuccess() 和 doOnError . 但目前我的代码无法编译。另外请注意,如果我的'getMaybe'没有返回任何东西,我希望在flatmap中得到一个null值作为参数,这样我就可以处理null和notnull的情况(如代码中所示)。

    private Maybe<DataSnapshot> getMaybe(String key) {
        // external API that returns a maybe
    }

    private Completable updateChildren(mDatabase, childUpdates) {
        // external APIÂ that returns a Completable
    }

    // I'd like my function to return a Completable but it doesn't compile now
    public Completable saveUser(String userKey, User user) {
        return get(userKey)
                .flatMap(a -> {
                    Map<String, Object> childUpdates = new HashMap<>();

                    if (a != null) {
                        // add some key/values to childUpdates
                    }

                    childUpdates.put(DB_USERS + "/" + userKey, user.toMap());

                    // this returns a Completable
                    return updateChildren(mDatabase, childUpdates)
                });
    }

2 回复 | 直到 7 年前

dmarquina 7 年前

首先,记住Maybe是用来获取一个元素的,无论是空的还是错误的我重构了下面的代码,使posible返回一个可完成的

public Completable saveUser(String userKey, User user) {
    return getMaybe(userKey)
            .defaultEmpty(new DataSnapshot)
            .flatMapCompletable(data -> {
                Map<String, Object> childUpdates = new HashMap<>();

                //Thanks to defaultempty the object has an 
                //Id is null (it can be any attribute that works for you) 
                //so we can use it to validate if the maybe method
                //returned empty or not
                if (data.getId() == null) {
                    // set values to the data
                    // perhaps like this
                    data.setId(userKey);
                    // and do whatever you what with childUpdates
                }

                childUpdates.put(DB_USERS + "/" + userKey, user.toMap());

                // this returns a Completable
                return updateChildren(mDatabase, childUpdates);
            });
}

PerrierCitror 7 年前

这就是我最终想出的解决办法。

    public Completable saveUser(String userKey, User user) {
        return getMaybe(userKey)
                .map(tripListSnapshot -> {
                    Map<String, Object> childUpdates = new HashMap<>();
                    // // add some key/values to childUpdates
                    return childUpdates;
                })
                .defaultIfEmpty(new HashMap<>())
                .flatMapCompletable(childUpdates -> {
                    childUpdates.put(DB_USERS + "/" + userKey, user.toMap());
                    return updateChildren(mDatabase, childUpdates);
                });
    }