Angular2 APP_INITIALIZER不一致 [英] Angular2 APP_INITIALIZER not consistent

问题描述

我正在使用APP_INITIALIZER，就像在此答案中所建议的那样，我的服务返回了承诺，但它没有总是等待它解决，我可以看到我的组件console.logging未定义，然后服务记录了下载的对象.

I am using APP_INITIALIZER like it is recommended in this answer, with my service returning a promise, but it doesn't always wait for it to resolve and I can see my component console.logging undefined and then the service logging the downloaded object.

在加载此数据之前，我需要应用不执行任何操作.

I need the app to not do anything before this data is loaded.

app.module.ts

app.module.ts

import { NgModule, APP_INITIALIZER } from '@angular/core';
import { Http, HttpModule, JsonpModule } from '@angular/http';
import { UserService } from '../services/user.service';

<...>
@NgModule({
  imports: [
    BrowserModule,
    HttpModule,
    FormsModule,
    JsonpModule,
    routing
  ],
  declarations: [
    AppComponent,
    <...>
  ],
  providers: [
    <...>
    UserService,
    {provide: APP_INITIALIZER,
      useFactory: (userServ: UserService) => () => userServ.getUser(),
      deps: [UserService, Http],
      multi: true
    }
  ],
  bootstrap: [AppComponent]

user.service.ts

user.service.ts

@Injectable()
export class UserService {

    public user: User;
    constructor(private http: Http) { }

    getUser(): Promise<User> {
        console.log('get user called');
        var observable= this.http.get('/auth/getuser', { headers: getHeaders() })
            .map(extractData);

        observable.subscribe(user => {this.user = user;
            console.log(this.user)});
        return observable.toPromise();
    }
}

推荐答案

尝试以下代码:

getUser(): Promise<User> {
    console.log('get user called');
    var promise = this.http.get('/auth/getuser', {headers: getHeaders()})
        .map(extractData)
        .toPromise();
    promise.then(user => {
        this.user = user;
        console.log(this.user);
    });
    return promise;
}

我正面临着同样的问题，而使用诺言而不是可观察到的技巧对我来说是成功的秘诀.

I was facing the same problem, and using a promise instead of a observable did the trick for me.

这篇关于Angular2 APP_INITIALIZER不一致的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！