如何对多个可观察物进行排序 [英] How to sequence multiple observables

问题描述

我一般都不是Angular2和前端开发人员，所以如果我没有找到明显的答案，我深表歉意.

I'm new to Angular2 and front-end development in general, so my apologies if I'm missing the obvious answer.

我正在使用Angular2应用.我不确定要在正在处理的组件中完成任务的最佳方法.

I'm working on an Angular2 app. I'm not sure about the best way to accomplish a task in a component I'm working on.

ngOnInit() {
    console.log("init component");
    console.log(this.activatedRoute);

    this.paramSub = this.activatedRoute.params.switchMap(
        (params: Params) => this.personSearchService.getPerson(params['personId']))
        .subscribe(result => this.personDetails = result);

    this.orgSub = this.personSearchService.getPersonFedOrgs(0).subscribe(
        results => this.orgs = results,
        error => console.log(error)
    );

    //pseudo-code
    watch this.orgs and this.personDetails
        if change
            do logic
}

在OnInit生命周期钩子过程中，我做了两件事，我在服务中获取并使用了路由参数，还从第二个服务中获取了组织列表.所有这些都工作正常.

During the OnInit lifecyle hook, I do two things, I get and use a route parameter with a service and I also get a list of organizations from a second service. All of that's working fine.

我标记为伪代码的部分是我要添加的功能.我想获取前两个服务调用的结果并执行一些业务逻辑.

The section I've labeled as psuedo-code is functionality I want to add. I want to take the results of the first two service calls and execute some business logic.

我知道我不能直接使用this.personDetails和this.orgs，因为它们将是未定义的(直到解决了异步调用).因此，我认为我需要将它们包装在Observable中，以便每次更新它们时都可以执行一些逻辑.但是我不确定如何做到这一点.任何朝着正确方向的指针将不胜感激.

I know that I can't directly use this.personDetails and this.orgs because they'll be undefined (until the async calls are resolved). So I think I need to wrap them in an Observable so that I can execute some logic each time they're updated. But I'm not exactly sure how to do that. Any pointers in the right direction would be greatly appreciated.

推荐答案

您可以使用 cobmineLatest()运算符.为了便于阅读，我对代码进行了一些重构:

You can use cobmineLatest() operator. I refactored the code a bit for readability:

personDetails$ = this.activatedRoute.params
  .map((params: Params) => params['personId'])
  .switchMap(id => this.personSearchService.getPerson(id))

orgs$ = this.personSearchService.getPersonFedOrgs(0)

Observable.combineLatest(personDetails$, orgs$)
  .subscribe(([details, orgs]) => {
    console.log(details, orgs);
  })

别忘了导入运算符:

import 'rxjs/add/observable/combineLatest';

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