TypeError：无法读取IONIC 5中null的属性'canDeactivate'

Question

bounty到期在5天内。该问题的答案有资格获得+ 50声望赏金。Tapas Mukherjee想要引起更多关注对此问题。

我无法在Ionic 5中实现canDeactivate保护。以下是我的代码。

model.ts

export interface isDeactivatable {
    canDeactivate: () => Observable<boolean> | Promise<boolean> | boolean;
 }

leave-page.guard.ts

export class LeavePageGuard implements CanDeactivate<isDeactivatable>{
  canDeactivate(
    component: isDeactivatable
  ): Observable<boolean> | Promise<boolean> | boolean {
    console.log('LeavePageGuard');
    return component.canDeactivate();
  }

}

test-page.ts

export class TestPage implements OnInit, isDeactivatable{
      canDeactivate(): Observable<boolean> | Promise<boolean> | boolean {
        console.log('canDeactivate in TestPage');
        return true;
      }
}

home-routing.Module.ts

const routes: Routes = [
  {
    path: '',
    component: HomePage,
    children:[
      {
        path: 'test',
        loadChildren: () => import('../pages/test/test.module').then( m => m.TestPageModule),
        canDeactivate: [LeavePageGuard]
      }
]
}
]

离开TestPage时出现以下错误。我曾尝试在[App Module]和[TestPage Module]中将LeavePageGuard作为提供程序添加，但仍然遇到相同的错误。

core.js:6014 ERROR Error: Uncaught (in promise): TypeError: Cannot read property 'canDeactivate' of null
TypeError: Cannot read property 'canDeactivate' of null
    at LeavePageGuard.canDeactivate (leave-page.guard.ts:15)
    at router.js:5543
    at Array.map (<anonymous>)
    at runCanDeactivate (router.js:5532)
    at MergeMapSubscriber.project (router.js:5349)
    at MergeMapSubscriber._tryNext (mergeMap.js:46)
    at MergeMapSubscriber._next (mergeMap.js:36)
    at MergeMapSubscriber.next (Subscriber.js:49)
    at Observable._subscribe (subscribeToArray.js:3)
    at Observable._trySubscribe (Observable.js:42)
    at resolvePromise (zone-evergreen.js:797)
    at resolvePromise (zone-evergreen.js:754)
    at zone-evergreen.js:858
    at ZoneDelegate.invokeTask (zone-evergreen.js:391)
    at Object.onInvokeTask (core.js:39680)
    at ZoneDelegate.invokeTask (zone-evergreen.js:390)
    at Zone.runTask (zone-evergreen.js:168)
    at drainMicroTaskQueue (zone-evergreen.js:559)
    at invokeTask (zone-evergreen.js:469)
    at ZoneTask.invoke (zone-evergreen.js:454)

Answer 1

解决方案非常简单，我找到了here。问题在于延迟加载。给出的大多数解决方案不是针对延迟加载的问题。

我将canDeativate防护从应用程序路由移到了该特定页面的模块路由。像魅力一样运作。