Question

我正在玩角度2教程的英雄应用程序，现在我有这个组件

import { Component, OnInit } from '@angular/core'
import { Subject } from 'rxjs/Subject';
import { Hero } from "./hero";
import { Router } from "@angular/router";
import { HeroService } from "./hero.service";
import { BehaviorSubject } from "rxjs/BehaviorSubject";


@Component({
    selector: 'hero-search',
    templateUrl: 'app/hero-search.component.html',
    styleUrls: ['app/hero-search.component.css'],
})
export class HeroSearchComponent implements OnInit{
    heroes: Hero[];
    isLoading: BehaviorSubject<boolean> = new BehaviorSubject(false);
    error: any;
    private searchNameStream = new Subject<string>();

    constructor(
        private heroService: HeroService,
        private router: Router
    ) {}

    ngOnInit() {
        this.searchNameStream
            .debounceTime(400)
            .distinctUntilChanged()
            .switchMap(name => {
                this.isLoading.next(true);
                return this.heroService.getHeroesByName(name)
            })
            .subscribe(
                heroes => this.heroes = heroes,
                error => this.error = error,
                () => {
                    console.log('completed');
                    this.isLoading.next(false);
                })
    }

    // Push a search term into the observable stream.
    search(Name: string): void {
        this.searchNameStream.next(Name)
    }

    gotoDetail(hero: Hero): void {
        let link = ['/detail', hero.id];
        this.router.navigate(link);
    }

}

问题是，如果我理解正确，订阅需要三个回调参数.subscribe(success, failure, complete);。但就我而言，完整的部分永远不会被执行。我想这与switchMap的工作原理有关。我是对的吗？

Answer 1

The searchNameStream never completes, so the observable obtained from switchMap never completes either.

Every time an event is emitted by the searchNameStream, heroService.getHeroesByName() is called and all the events emitted by this "inner" observable are reemitted by the "outer" observable, until a new event is emitted by the searchNameStream, and this process repeats. You subscribed to the outer observable, which will only complete when the searchNameStream completes.

angular 2 Observable完全没有被称为

1 个答案: