如何延长使用依赖注入组件在角2？ [英] How to extend a component with dependency injection in Angular 2?

问题描述

我有以下类 ModuleWithHttp ：

@Injectable()
export default class {
  constructor(private fetchApi: FetchApi) {}
}

和我想用它如下：

@Component({
  selector: 'main',
  providers: [FetchApi]
})
export default class extends ModuleWithHttp {
  onInit() {
    this.fetchApi.call();
  }
}

这样通过扩展已经注入的依赖我想在它的孩子给它的访问一个超类。

so by extending a super class that already injects a dependency I want to have an access to it in its children.

我试过很多不同的方式，甚至有超一流的组件：

I tried many different ways, even having super-class as a component:

@Component({
  providers: [FetchApi]
})
export default class {
  constructor(private fetchApi: FetchApi) {}
}

但尽管如此， this.fetchApi 是空，即使是在超一流的。

But still, this.fetchApi is null, even in super-class.

推荐答案

您必须注入fetchAPI在超类和它向下传递给基类

You have to inject fetchAPI in the super class and pass it down to the base class

export default class extends ModuleWithHttp {

  constructor(fetchApi: FetchApi) {
     super(fetchApi);
  }   

  onInit() {
    this.fetchApi.call();
  }
}

这是DI是如何工作的，一般的功能。超类将通过继承来实例化基地，但你必须提供所需参数的基础。

This is a feature of how DI works in general. The super class will instantiate the base via inheritance, but you have to supply the required parameters to the base.

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