CanActivate vs. CanActivateChild with component-less routes

Question

The angular2 documentation about Route Guards left me unclear about when it is appropriate to use a CanActivate guards vs. a CanActivateChild guard

Answer 1

TL;DR: CanActivate and CanActivateChild are not for a component-less route.

I believe the docs simply overlooked the needless of both guards in a component-less route, as the intention was simply to demonstrate the component-less route in a particular mile-stone of the docs and the the use of both guards in another.

The use of both guards can be very useful in specific scenarios, for example: An admin dashboard allowing login to see several components, like mailing, logging statistics, resource usage etc. - at this level the access is restricted by the CanActivate guard - when trying to navigate to each component the roles of each admin-user is checked by the CanActivateChild guard.

Answer 2

One reason I can think of is timeouts.

I'm starting to work with Angular 2, using an authentication provider. This provider expires a session which has been idle for more than a certain amount of time.

In a common situation where you leave your computer logged in and your session expires, the next navigation you try MUST validate your current situation. If you are navigating between child routes, I think CanActivateChild is the guard that will detect the expired session, and trigger a redirect to login, while CanActivate won't trigger at all.

Disclaimer: This came from the top of my head, I haven't implemented it yet.

Answer 3

What if you have 10 children defined.

Then canActivateChild only needs to go in one place if they all have a common requirement, as opposed to 10 canActivate on each child.

Answer 4

I also confused the angular2's documentation about routeGuard. what's the difference between the CanActivate guard and CanActivateChild guard.

I have some findings,I hope this will help you.

in the auth-guard.service.ts file

  canActivate(route: ActivatedRouteSnapshot, state: RouterStateSnapshot): boolean {
let url: string = state.url;

return this.checkLogin(url);
}

canActivateChild(route: ActivatedRouteSnapshot, state: RouterStateSnapshot): boolean {
return this.canActivate(route, state);
}

because the canActivate method is called in the canActivateChild function. you can write a snippet of code that don't call the canActivate method in the canActivateChild function.

Answer 5

From the docs:

As we learned about guarding routes with CanActivate, we can also protect child routes with the CanActivateChild guard. The CanActivateChild guard works similarly to the CanActivate guard, but the difference is its run before each child route is activated. We protected our admin feature module from unauthorized access, but we could also protect child routes within our feature module.

Here's a practical example:

1. navigating to /admin
2. canActivate is checked
3. You navigate between the children of /admin route, but canActivate isn't called because it protects /admin
4. canActivateChild is called whenever changing between children of the route its defined on.

I hope this helps you, if still unclear, you can check specific functionality by adding guards debugging them.

Answer 6

In real world, I feel it is redundant to use the same guard for the parent and all its children.

For a better example, suppose you have roles for admin users (Edit/View), you can add a guard for "Edit" only tabs.

    RouterModule.forChild([
      {
        path: 'admin',
        component: AdminComponent,
        canActivate: [AuthGuard],  //1 - redirect to login page if not logged in
        children: [
          //View Access
          {
            ......
          },
          //Edit Access
          {
            path: '',
            canActivateChild: [EditGuard], //2 - display "you don't have Edit permission to access this page"
            children: [
              { path: 'crises', component: ManageCrisesComponent },
              { path: 'heroes', component: ManageHeroesComponent },
              { path: '', component: AdminDashboardComponent }
            ]
          }
        ]
      }
    ])