如何使Angular2在渲染组件之前等待一个承诺 [英] How to make Angular2 wait for a promise before rendering component

问题描述

首先:是的，我已经对此进行了Google搜索，并且

First: Yes, I have Googled this beforehand, and the solution that came up isn't working for me.

上下文

我有一个Angular 2组件来调用服务，并且一旦收到响应，就需要执行一些数据操作:

I have an Angular 2 component that calls a service, and needs to perform some data manipulation once it receives the response:

ngOnInit () {
  myService.getData()
    .then((data) => {
      this.myData = /* manipulate data */ ;
    })
    .catch(console.error);
}

在其模板中，该数据将传递到子组件:

In its template, that data is passed to a child component:

<child-component [myData]="myData"></child-component>

这将导致错误，表明孩子正在获得myData的未定义值.上面发布的Google结果讨论了使用Resolver的问题，但这对我不起作用.

This is causing an error that the child is getting myData as undefined. The Google result posted above talks about using Resolver but that isn't working for me.

当我创建一个新的解析器时:

When I create a new resolver:

import { Injectable } from '@angular/core';
import { Resolve, ActivatedRouteSnapshot } from '@angular/router';
import { Observable } from 'rxjs/Rx';
import { MyService } from './my.service';

@Injectable()
export class MyResolver implements Resolve<any> {
    constructor(private myService: MyService) {}

    resolve (route: ActivatedRouteSnapshot): Observable<any> {
        return Observable.from(this.myService.getData());
    }
}

app.routing.ts

const appRoutes: Routes = [
  {
    path: 'my-component',
    component: MyComponent,
    resolve: {
        myData: MyDataResolver
    }
  }
];

export const routing = RouterModule.forRoot(appRoutes);

我收到一个错误，提示MyDataResolver没有提供者.当我将MyDataResolver添加到 app.component.ts 中的providers属性中时，情况仍然如此:

I get an error that there is no provider for MyDataResolver. This is still the case when I add MyDataResolver to the providers property in app.component.ts:

@Component({
  selector: 'my-app',
  templateUrl: 'app/app.component.html',
  providers: [
        MyService,
        MyResolver
  ]
})

使用此接口的界面已更改吗?

Has the interface for using this changed?

推荐答案

路由器支持从resolve()返回的Promise或Observable.
另请参见 https://angular.io/docs/ts/latest/api/router/index/Resolve-interface.html

The router supports a promise or an observable returned from resolve().
See also https://angular.io/docs/ts/latest/api/router/index/Resolve-interface.html

这应该做您想要的:

@Injectable()
export class MyResolver implements Resolve<any> {
    constructor(private myService: MyService) {}

    resolve (route: ActivatedRouteSnapshot): Promise<any> {
        return this.myService.getData();
    }
}

另请参见 https://angular.io/docs/ts/latest/guide/router.html#！#resolve-guard

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