ForkJoin 2 BehaviorSubjects [英] ForkJoin 2 BehaviorSubjects

问题描述

我有两个行为主题流，我想在没有运气的情况下分叉加入.正如我想象的那样，它返回了它的最后两个值.这有可能以某种方式实现吗?

I have two behaviour subject streams what I'm trying to forkJoin with no luck. As I imagined it gives back the two last values of it. Is this possible to implement it somehow?

它不是在主语之后调用.

It is not called after the subject.

let stream1 = new BehaviorSubject(2);
let stream2 = new BehaviorSubject('two');

Observable.forkJoin(stream1, stream2)
    .subscribe(r => {
         console.log(r);
    });

推荐答案

注意什么 forkJoin() 实际上是从它的文档中得到的:

Note what forkJoin() actually does from its documentation:

等待 Observable 完成，然后合并它们最后发出的值.

Wait for Observables to complete and then combine last values they emitted.

这意味着 forkJoin() 在所有输入 Observable 完成时发出一个值.当使用 BehaviorSubject 时，这意味着在它们两个上显式调用 complete():

This means that forkJoin() emits a value when all input Observable are complete. When using BehaviorSubject this means explicitly calling complete() on both of them:

import { Observable, BehaviorSubject, forkJoin } from 'rxjs';

const stream1 = new BehaviorSubject(2);
const stream2 = new BehaviorSubject('two');

forkJoin(stream1, stream2)
  .subscribe(r => {
    console.log(r);
  });

stream1.complete();
stream2.complete();

观看现场演示:https://stackblitz.com/edit/rxjs-9nqtx6

2019 年 3 月:针对 RxJS 6 进行了更新.

March 2019: Updated for RxJS 6.

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