Make AJAX request before bootstrapping Angular2 application [duplicate]

问题

In my Angular2 application I need to make a call to some function from AuthenticationService and bootstrap application based on results of this call. The problem is that AuthenticationService has dependency on HTTP from @angular/http and I have very little idea of how to build http service manually before calling bootstrap function. Accepted answer in this question angular2 bootstrap with data from ajax call(s) describes what I want to achieve perfectly, but unfortunately it was given to some previous version of Angular2.

I tried to create http service this way:

let injector = ReflectiveInjector.resolveAndCreate(HTTP_PROVIDERS)
let http = injector.get(Http);

but I got null reference exception in XsrfCookieStrategy or something like that. I believe it is possible to inject some empty XsrfStrategy, but it seems to be more like a hack than a good solution. So the question is: are there any good (official) way to bootstrap Angular2 application with providing some dependencies up-front similar to the link I added above.

回答1:

class AuthService {
  isLoggedIn:BehaviorSubject<boolean> = BehaviorSubject<boolean>(false);
  checkLogin(http:Http) {
    return http.get(...)
    .map(result => result.json())
    .do(result => this.isLoggedIn.next(result)
  }
}

bootstrap(AppComponent, [
  HTTP_PROVIDERS,
  AuthService,
  { provide: APP_INITIALIZER, 
    useFactory: (authService:AuthService) => authService.checkLogin(),
    deps: [AuthService],
    multi: true
  }
]);

See also How to pass parameters rendered from backend to angular2 bootstrap method

来源：https://stackoverflow.com/questions/38707076/make-ajax-request-before-bootstrapping-angular2-application

标签

angular

bootstrapping