我在加载一个类到Angular组件时遇到了一个问题。很长一段时间以来，我一直在试图解决这个问题;我甚至试着把它们都合并到一个文件中。我拥有的是:
Application.ts
/// <reference path="../typings/angular2/angular2.d.ts" />
import {Component,View,bootstrap,NgFor} from "angular2/angular2";
import {NameService} from "./services/NameService";
@Component({
selector:'my-app',
injectables: [NameService]
})
@View({
template:'<h1>Hi {{name}}</h1>' +
'<p>Friends</p>' +
'<ul>' +
' <li *ng-for="#name of names">{{name}}</li>' +
'</ul>',
directives:[NgFor]
})
class MyAppComponent
{
name:string;
names:Array<string>;
constructor(nameService:NameService)
{
this.name = 'Michal';
this.names = nameService.getNames();
}
}
bootstrap(MyAppComponent);
服务/ NameService.ts
export class NameService {
names: Array<string>;
constructor() {
this.names = ["Alice", "Aarav", "Martín", "Shannon", "Ariana", "Kai"];
}
getNames()
{
return this.names;
}
}
我一直得到一个错误消息说没有NameService的提供者。
有人能帮我找出我的代码的问题吗?
在Angular 2中，你可以在三个地方“提供”服务:
引导
根组件
其他组件或指令
“引导提供者选项用于配置和覆盖Angular自己的预注册服务，比如路由支持。”——参考
如果你只想在整个应用中使用一个NameService实例(例如，Singleton)，那么将它包含在根组件的providers数组中:
@Component({
providers: [NameService],
...
)}
export class AppComponent { ... }
砰砰作响
如果你希望每个组件都有一个实例，可以使用组件配置对象中的providers数组:
@Component({
providers: [NameService],
...
)}
export class SomeOtherComponentOrDirective { ... }
更多信息请参见分层注入器文档。
您需要将其添加到providers数组中，该数组包含组件上的所有依赖项。
请看angular文档中的这一部分:
在组件中注册提供者
下面是修改后的HeroesComponent，它注册了HeroService
提供者数组。
import { Component } from '@angular/core';
import { HeroService } from './hero.service';
@Component({
selector: 'my-heroes',
providers: [HeroService],
template: `
<h2>Heroes</h2>
<hero-list></hero-list>
`
})
export class HeroesComponent { }
When to use NgModule versus an application component
On the one hand, a provider in an NgModule is registered in the root
injector. That means that every provider registered within an NgModule
will be accessible in the entire application.
On the other hand, a provider registered in an application component
is available only on that component and all its children.
Here, the APP_CONFIG service needs to be available all across the
application, so it's registered in the AppModule @NgModule providers
array. But since the HeroService is only used within the Heroes
feature area and nowhere else, it makes sense to register it in the
HeroesComponent.
Also see "Should I add app-wide providers to the root AppModule or the
root AppComponent?" in the NgModule FAQ.
所以在你的情况下，简单地改变注入到提供商如下所示:
@Component({
selector: 'my-app',
providers: [NameService]
})
在Angular的新版本中，@View和其他一些东西也消失了。
欲了解更多信息，请访问这里。
