Question

我正在使用Angular 2.0.0-beta.15。我试图在组件中使用@CanActivate。下面是一段代码。

@CanActivate((next: ComponentInstruction, previous: ComponentInstruction) =>  { 
console.log('loggedIn:' + isLoggedIn(next, previous));
console.log('isExists:' + isExists(next, previous))
})export class ParentLandingComponent {}

现在isExists.ts中的相关代码如下：

import {Injector} from 'angular2/core';
import {appInjector} from './app-injector';
import {DataService} from '../services/data-services.service';
export const isExists = (next: ComponentInstruction, previous: ComponentInstruction) => {
let injector: Injector = appInjector(); 
let userService: UserService = injector.get(UserService);
let router: Router = injector.get(Router);
let cookieService: CookieService = injector.resolveAndInstantiate(CookieService);

    dataService.isExists().subscribe(result => {
        console.log('isExists:' + result);
        if (result) {
            console.log('result:' + result);
            cookieService.removeAll();
            router.navigate(['Login']);
            return true;
        } else {
           return false;
        }
     });
};

我也在boot.ts中添加了以下内容。

///<reference path="../../node_modules/angular2/typings/browser.d.ts"/>
  import {bootstrap} from 'angular2/platform/browser';
  import {provide} from 'angular2/core';
  import {ROUTER_PROVIDERS, ROUTER_DIRECTIVES, RouteConfig, Location, LocationStrategy, HashLocationStrategy} from 'angular2/router';
  import {AppComponent} from './app.component';
  import {HTTP_PROVIDERS} from 'angular2/http';
  import 'rxjs/Rx';
  import {DataService} from './services/data-services.service';
  import {StateService} from './services/current-user-state.service';
  import {appInjector} from './utils/app-injector';
  import {HttpClient} from './services/http-client.service';
   bootstrap(AppComponent, [DataService, StateService, HttpClient, ROUTER_PROVIDERS, HTTP_PROVIDERS,
provide(LocationStrategy, { useClass: HashLocationStrategy })])
.then(appRef => {
    appInjector(appRef.injector);
});

当我运行时，我在@CanAnnotation中获得isExists（next，previous）的值为undefined而不是boolean值。在isExists.ts里面，我得到了正确的值。但是当我根据结果的值传递布尔值时，我在注释部分得到了未定义。任何人都可以帮助我知道这可能是什么问题？

Answer 1

CanActivate()注释中的lambda必须返回boolean|Promise<boolean>。根据您的代码，它没有返回任何内容。我猜你会从isExists()返回值。但是，isExists()也不会返回任何与其undefined相关的内容。我看到你试图从subscribe方法返回true/false。但该返回是异步的，不会按预期解决。

我建议您将Observable转换为Promise<boolean>并将其从isExists()

返回

isExists（）中的相关部分：

return dataService.isExists().map(result => { // change subscribe to 'map' in order to change the return type of the observable and do the other stuff 
    console.log('isExists:' + result);
    if (result) {
        console.log('result:' + result);
        cookieService.removeAll();
        router.navigate(['Login']);
        return true;
    } else {
       return false;
    }
 }).toPromise();

@CanActivate（）：

@CanActivate((next: ComponentInstruction, previous: ComponentInstruction) =>  { 
    console.log('loggedIn:' + isLoggedIn(next, previous));
    return isExists(next, previous);
})
export class ParentLandingComponent {}

无法在组件中的@CanActivate装饰器中获得服务的价值

1 个答案: