带 rx 的条件查询串联

Question

我遇到了以下问题。我有一个从具有属性 isMember 的服务器请求的基本对象。如果属性为真，我想向端点 1、2 和 3 发出请求。
如果属性为假，我只想向端点 1 发出请求。

我在下面写了一个基本的用例示例，其中包含所有相关类显示程序流程。这个问题的相关部分在评论的 UserViewModel::loadData 中。

我不知道如何用 Rx 实现这个...你能给我一些提示吗？

干杯！

interface Controller {

    Observable<BaseInfoDto> getBaseInfo(long id);

    Observable<AccountDto> getAccount(long id);

    Observable<MemberFriendsDto> getFriends(long id);

    Observable<MemberLikesDto> getLikes(long id);
}

...

class UserModel {

    private final long userId;

    private BaseInfoDto baseInfo;

    private AccountDto accountData;

    private MemberFriendsDto friends:

    private MemberLikesDto likes;

    public UserModel(long userId) {
        this.userId = userId;
    }

    public long getId() {
        return userId;
    }

    public BaseInfoDto getBaseInfo() {
        return baseInfo;
    }

    public void setBaseInfo(BaseInfoDto baseInfo) {
        this.baseInfo = baseInfo;
    }

    // … etc.

}

...

class UserViewModel {

    private final Controller controller;

    private final UserModel userModel;

    public UserViewModel(Controller controller, long userId) {
        this.controller = controller;
        userModel = new UserModel(userId);
    }

    public Completable loadData() {
        return controller.getBaseInfo(userModel.getId())
            .doOnNext(this::setBaseInfo)
            .toCompletable()
            .mergeWith(loadAccountData())

            // if, after BaseInfoDto arrived, BaseInfoDto::isMember is true 
            // load the following other queries
            // else stop after merging loadAccountData

            .mergeWith(loadFriends)
            .mergeWith(loadLikes)
            .doOnTerminate(() -> {
                // notify data bindings
            });
    }

    private Completable loadAccountData() {
        return controller.getAccount(userModel.getId())
            .doOnNext(this::setAccountData)
            .toCompletable()
            .onErrorComplete();
    }

    private Completable loadFriendsData() {
        // like loadAccountData
    }

    private Completable loadLikesData() {
        // like loadAccountData
    }

    private void setBaseInfo(BaseInfoDto baseInfo) {
        userModel.setBaseInfo(baseInfo);
    }

    private void setAccountData(AccountDto accountData) {
        userModel.setAccountData(accountData);
    }

    // … etc.
}

...

class UserDetailsView {

    private final long selectedUser;

    private final ThreadManager threadManager;

    private final UserViewModel viewModel;

    public UserDetailsView(long selectedUser, ThreadManager threadManager) {
        this.selectedUser = selectedUser;   
        this.threadManage = threadManager;
        viewModel = new UserViewModel(selectedUser);
    }

    void onViewInstantiated() {
        // lots of stuff happens
        loadUserData();
    }

    private void loadUserData() {
        viewModel.loadData()
            .observeOn(threadManager.getMainThread())
            .subscribe(this::showError, this::bindUserData);
    }

    private void showError() {
        // foo
    }

    private void bindUserData() {
        // bar
    }
}

...只是为了完整

interface ThreadManager {

    Thread getMainThread();
}

Answer 1

根据isMember结果使用flatMap：

controller
  .getBaseInfo(userModel.getId())
  .flatMap(info -> {
    if (info.isMember()) 
      return endpoint1
            .mergeWith(endpoint2)
            .mergeWith(endpoint3);
    else 
      return endpoint1;
})...

带 rx 的条件查询串联

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