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Guards

CanActivate

Interface that a class can implement to be a guard deciding if a route can be activated. If all guards return true, navigation continues. If any guard returns false, navigation is cancelled. If any guard returns a UrlTree, the current navigation is cancelled and a new navigation begins to the UrlTree returned from the guard.
interface CanActivate {
canActivate(
route: ActivatedRouteSnapshot,
state: RouterStateSnapshot):
Observable<boolean | UrlTree> | Promise<boolean | UrlTree> | boolean | UrlTree
}

Description

The following example implements a CanActivate function that checks whether the current user has permission to activate the requested route
class UserToken {}
class Permissions {
canActivate(user: UserToken, id: string): boolean {
return true;
}
}
@Injectable()
class CanActivateTeam implements CanActivate {
constructor(private permissions: Permissions, private currentUser: UserToken) {}
canActivate(
route: ActivatedRouteSnapshot,
state: RouterStateSnapshot
): Observable<boolean|UrlTree>|Promise<boolean|UrlTree>|boolean|UrlTree {
return this.permissions.canActivate(this.currentUser, route.params.id);
}
}

How to implement a Guard?

Here, the defined guard function is provided as part of the Route object in the router configuration:
content_copy@NgModule({
imports: [
RouterModule.forRoot([
{
path: 'team/:id',
component: TeamComponent,
canActivate: [CanActivateTeam]
}
])
],
providers: [CanActivateTeam, UserToken, Permissions]
})
class AppModule {}