I am unable to implement canDeactivate guard in Ionic 5. Following are my code.
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]
}
]
}
]
I am getting the following error when leaving TestPage
.
I have tried adding LeavePageGuard
in App Module and in TestPage Module as a provider but still getting the same error.
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)
The solution was very easy and I found it here. The issue was with lazy loading. The majority of the solutions are given not for Lazy loading issue.
I moved the canDeativate guard from app routing to that particular page's module routing. Worked like a charm.
test-rouring.module.ts
const routes: Routes = [
{
path: '',
component: TestPage
canDeactivate: [ LeavePageGuard ]
}