Question

我试图将@Injectable AppState注入单身人士：

@Injectable()
export class AppState {
  public user: string;

  constructor() {

  }
...

我已将AppModule设置为provider：

// Application wide providers
const APP_PROVIDERS = [
  AppState
];

@NgModule({
  bootstrap: [ App ],
  declarations: [
    App,
    ErrorComponent
  ],
  imports: [ // import Angular's modules
    BrowserModule,
    FormsModule,
    HttpModule,
    RouterModule.forRoot(ROUTES, { useHash: true })
  ],
  providers: [
    APP_PROVIDERS
  ]
})

所以，我刚创建了"submodule"：

@NgModule({
  //...
  providers: [ UsersService, AppState ]
})
export default class LoginModule {

在LoginComponent我做：

export class Login implements OnInit {

    constructor(private appState: AppState) {}

    public doLogin():void {
        this.appState.user = this.form.value.mail;
    }
}

然而，在名为Profile的另一个组件上，this.appState.user似乎未定义。

@NgModule({
  //...
  providers: [ AppState ]
})
export default class ProfileModule { /... }

@Component({
  //...
})
export class Profile implements OnInit {

  constructor(private appState: AppState) {

  }

  ngOnInit():void {
    this.user = this.appState.user;  <<<<<<<<<<<<< it's undefined
  }
}

如果我之前在另一个组件中设置了this.appState.user，为什么{{1}}会被解决？

Angular2：注射为单身

0 个答案: