服务可观察不在组件NgOnInIt中工作 - Angular2
我的getHero服务可观察未在HeroDetail组件中的NgOnInIt中调用。服务可观察不在组件NgOnInIt中工作 - Angular2
我可以使用HTTP获取&显示数据表&路由到单击该行时的详细信息页面。然后,我使用url的“id”参数来获取id,但同样不能使用getHero函数来获取特定的行详细信息。
身份证显示在控制台中,但英雄来了未定义。我尝试了很多东西,但目前为止还没有工作。任何帮助将不胜感激。
以下是我的代码供参考。
hero.service.ts
import { Injectable } from '@angular/core';
import { Http, Response } from '@angular/http';
import { Observable } from 'rxjs/Observable';
import 'rxjs/add/operator/catch';
import 'rxjs/add/operator/map';
import { Hero } from './hero';
@Injectable()
export class HeroService {
heroes: Hero[];
hero: Hero;
private heroesUrl = 'SERVICE URL';
constructor (private http: Http) {}
getHeroes(): Observable<Hero[]> {
return this.http.get(this.heroesUrl)
.map(this.extractData)
.catch(this.handleError);
}
private extractData(res: Response) {
let body = res.json()['data'];
console.log(body);
return body || { };
}
private handleError (error: Response | any) {
// In a real world app, you might use a remote logging infrastructure
let errMsg: string;
if (error instanceof Response) {
const body = error.json() || '';
const err = body.error || JSON.stringify(body);
errMsg = `${error.status} - ${error.statusText || ''} ${err}`;
} else {
errMsg = error.message ? error.message : error.toString();
}
console.error(errMsg);
return Observable.throw(errMsg);
}
getHero(id: number): Observable<Hero> {
return this.getHeroes()
.map(heroes => heroes.find(hero => hero.cc_id == id));
}
}
英雄detail.component.ts
import { Component } from '@angular/core';
import { Router, ActivatedRoute, Params } from '@angular/router';
import { HeroService } from './hero.service';
import { Hero } from './hero';
@Component({
template: `
<h2>INNER PAGE {{ this.id }}</h2>
`,
providers: [HeroService]
})
export class HeroDetailComponent {
errorMessage: string;
hero: Hero;
heroes: Hero[];
id: number;
mode = 'Observable';
constructor (
private service: HeroService,
private route: ActivatedRoute,
private router: Router
) {}
ngOnInit() { this.getHeroes() }
getHeroes() {
this.id = this.route.snapshot.params['id'];
console.log(this.id);
this.service.getHero(this.id).subscribe(hero => this.hero = hero);
console.log(this.hero);
}
}
你正在登录this.hero
调用完成之前。这是因为Http调用是异步完成的。
getHeroes() {
this.id = this.route.snapshot.params['id'];
console.log(this.id);
this.service.getHero(this.id).subscribe(hero => {
this.hero = hero;
console.log(this.hero);
});
}
谢谢@Mario。这工作! – Jamshed
很高兴帮助。 –
当使用Observables时,Observable外部的代码在实际的订阅模块执行之前执行,因为Observables是异步的。来自服务器的响应来自订阅的回调。尝试代码更改为以下:
this.service.getHero(this.id).subscribe(hero => {
this.hero = hero; // assign the class variable values here
console.log(this.hero);
});
}
的可能的复制[?我如何返回从angular2可观察/ HTTP /异步调用的响应(http://*.com/questions/43055706/how- do-i-return-the-response-from-an-observable-http-async-call-in-angular2) – echonax