Angular 5 Observable需要等待，直到它被竞争

Question

在调用checkPermissions()方法之前，我需要等到getPermissions()可观测对象完成。但无论如何我都不能得到它...

我也试过使用async/await，但似乎对我也不起作用？

我需要我的权限，然后我才能检查它们，对吧。有什么想法？

如果有更好的办法，我洗耳恭听。

非常感谢。

​

import { Injectable } from '@angular/core';
import { Router, CanActivate, ActivatedRouteSnapshot } from '@angular/router';
import { AuthService } from './auth.service';

@Injectable()
export class RoleGuardService implements CanActivate {
  
  constructor(public auth: AuthService,public router: Router) { }

  canActivate(route: ActivatedRouteSnapshot): boolean {
    //This will be passed from the route config, on the data property
    const expectedRole = route.data.expectedRole;
    var hasPerm = this.loadAndCheckPermissions(expectedRole);

    console.log('done! ' + hasPerm);
    return hasPerm;
  }

  loadAndCheckPermissions(expectedRole) {
    var hasPermission = false;
    localStorage.clear();
    var myPermissions = localStorage.getItem('user-permissions');
    
    if (myPermissions === null) {
      console.log("PERMISSIONS from Server!");

      //You can't wait for an Observable or Promise to complete.
      //You can only subscribe to it to get notified when it completes or emits an event.
      this.auth.getPermissions()
        .subscribe(res => {
          localStorage.setItem('user-permissions', JSON.stringify(res.body));

          //Check permissions now
          //hasPermission = this.checkPermissions(expectedRole);
        });
    } else {
      hasPermission = this.checkPermissions(expectedRole); 
    }

    console.log('loadAndCheckPermissions ' + hasPermission);
    return hasPermission;
  }

  //Check a permission here
  checkPermissions(expectedRole) {
    return this.auth.checkPermission(expectedRole);
  }
}

​