TypeError: Cannot read property 'canDeactivate' of null in IONIC 5

Question

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;
 }

离开-page.guard.ts

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

}

测试-page.ts

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

首页-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。我尝试在 App 模块和 TestPage 模块中添加 LeavePageGuard 作为提供者，但仍然出现相同的错误。

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。问题在于延迟加载。大多数解决方案都不是针对延迟加载问题。

我将 canDeativate 守卫从应用程序路由移动到该特定页面的模块路由。工作得很好。

测试-rouring.module.ts

const routes: Routes = [
  {
    path: '',
    component: TestPage
    canDeactivate: [ LeavePageGuard ]
  }

TypeError: Cannot read property 'canDeactivate' of null in IONIC 5

TypeError: Cannot read property 'canDeactivate' of null in IONIC 5

ionic-framework

lazy-loading

ionic5

angular-route-guards

candeactivate