解决Promise时出现Angular2错误:输入"Promise< Hero []>"不可分配给"Hero []"类型 [英] Angular2 Error while resolving Promise: Type 'Promise<Hero[]>' is no t assignable to type 'Hero[]'
问题描述
已更新.
我正在关注Angular2教程 https://angular.io/docs/ts/latest/tutorial/toh-pt4.html
I am Following Angular2 tutorial from https://angular.io/docs/ts/latest/tutorial/toh-pt4.html
这是heroes.component.ts对HeroService的调用,
Here is the call to HeroService from heroes.component.ts,
Heroes.component.ts
import { Component , OnInit } from '@angular/core';
import { Hero } from './hero';
import { HeroService } from './hero.service';
@Component({
selector: 'my-heroes',
template: `
<h2>My Heroes</h2>
<ul class="heroes">
<li *ngFor="let hero of heroes">
<span class="badge">{{hero.id}}</span> {{hero.name}}
</li>
</ul> `,
})
export class HeroesComponent implements OnInit {
title = 'Tour of Heroes';
heroes: Hero[];
selectedHero: Hero;
constructor(private heroService : HeroService ){
}
getHeroes(): void{
this.heroService.getHeroes().then(heroes => this.heroes = heroes);
}
ngOnInit(): void{
this.getHeroes();
}
}
用HeroService编写的getHeroes()调用
And getHeroes() call written in HeroService
HeroService.ts
import { Injectable } from '@angular/core';
import { Hero } from './hero';
import { HEROES } from './mock-heroes';
@Injectable()
export class HeroService{
getHeroes() {
return Promise.resolve(HEROES);
}
}
我收到以下编译时错误:
I get the following compile time error :
错误TS2322:类型'Promise'不能分配给类型'Hero []'. 类型"Promise"中缺少属性"length".
error TS2322: Type 'Promise' is not assignable to type 'Hero[]'. Property 'length' is missing in type 'Promise'.
请提出建议.
推荐答案
将heroes: Hero[];
更改为heroes: any;
可解决此问题,但是控制台返回错误,因为ngFor
仅支持iterables
.
最后,代码会编译并运行该应用程序,但是有一个小问题困扰我.
Changing heroes: Hero[];
to heroes: any;
resolves the issue, however the console returns an error because ngFor
supports only iterables
.
At the end, the code compile and the app runs but there's this tiny issue that I find disrupting.
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