Angular 如何使用Behavior（）强制dataservice返回上一个值集

我正在写申请表。用户登录我的AuthService后，我使用next（）更改我的userService中Behavior Subject变量的值。在我的GuardService中，我想从变量中获取最新的值，但我总是获取初始值

用户服务

export class UserService {

private isAdmin = new BehaviorSubject<boolean>(true);
isCurrentUserAdmin = this.isAdmin.asObservable();

changeAdminRole(isAdmin: boolean) {
    // change the BehaviourSubject value
    this.isAdmin.next(isAdmin);
  }
}

应用模块

app.module.ts
imports: [
    BrowserModule,
    AppRoutingModule,
    BsDropdownModule.forRoot(),
    RouterModule.forRoot([
      {path: '', component: HomeComponent},
      {path: 'products', component: ProductsListComponent, canActivate: [AuthGuard, AdminGuard]},
      {path: 'shopping-cart', component: ShoppingCartComponent},
      {path: 'my-orders', component: MyOrdersComponent, canActivate: [AuthGuard, AdminGuard]},
      {path: 'check-out', component: CheckOutComponent, canActivate: [AuthGuard, AdminGuard]},
      {path: 'order-success', component: OrderSuccessComponent, canActivate: [AuthGuard, AdminGuard]},
      {path: 'login', component: LoginComponent},
      {path: 'admin/products', component: AdminProductsListComponent, canActivate: [AuthGuard, AdminGuard]},
      {path: 'admin/orders', component: AdminOrdersListComponent, canActivate: [AuthGuard, AdminGuard]},
      {path: '**', component: HomeComponent}
    ])
],
  providers: [AuthService, UserService, AuthGuard, AdminGuard]

---

当我导航到我想要保护的路由时，我希望AdminGuard的observable中的响应在UserService.changeAdminRole（）中设置了最新的值，当从我的AuthService调用时，但我总是得到null。

您试图从subscribe返回

true

，而不是从guard返回。你的卫兵总是假动作。还可以返回observable，最终解析为完全适合您的情况的布尔值：

canActivate() {
  return this.userService.isCurrentUserAdmin;
}

---

我认为

canActivate

是实现

canActivate（下一步：ActivatedRouteSnapshot，state:routerstatesapshot）：可观察的| Promise | boolean

这不是答案我只是确定代码

canActivate() {
  return this.userService.isCurrentUserAdmin;
}