Which Guard fired GuardsCheckEnd?

Question

We have a few router guards that protect different parts of our app.
In some cases, but not in all, we want to do things when the guard returns false.

router.events.subscribe(event => {
  if (event instanceof GuardsCheckEnd){
    if (!event.shouldActivate){
      //do stuff
    }
  }
});

The above code checks if any guard failed. We want to //do stuff only when a specific guard failed.
Is there a way to find out which guard failed?

There are several guards that require this logic, and only one that doesn't. If that's what it takes I'll do it, but there should be a cleaner answer. — AvailableName, Dec 16 '20 at 10:36
Also, the guard is much higher up in the route hierarchy, so it won't see the full path the user requested. Which is what we need for the `//do stuff`. — AvailableName, Dec 16 '20 at 11:10
Wild guess, but could you add some property to guard, which would be available in event? — Bojan Kogoj, Dec 16 '20 at 11:27
I don't think the guard is available in the event. https://angular.io/api/router/GuardsCheckEnd — AvailableName, Dec 16 '20 at 12:09
Then I suggest you create a service to hold state - guard will set activate true/false, and wherever you subscribe you can check for that guard value. — Bojan Kogoj, Dec 16 '20 at 12:36

score 0 · Accepted Answer · answered Dec 16 '20 at 12:52

From what I understand you want to know which guards fail, so you should record their value in guard service. This way it will be available to you at all times.

First guard

// FirstGuard
constructor(private guardService: GuardService) {}

canActivate() boolean {
  const canActivate = //some logic
  this.guardService.set('firstGuard', canActivate);
  return canActivate;
}

export class GuardService {
  private data = {};

  public set(guardName: string, value: boolean): void {
    this.data[guardName] = value;
  }

  public get(guardName: string): boolean {
    return this.data[guardName] ?? false; // choose default
  }

  public clear(): void {
    this.data = {};
  }
}

Where this interests you

router.events.subscribe(event => {
  if (event instanceof GuardsCheckStart) {
    // Make sure you don't have results from past events
    this.guardService.clear();
  }
  if (event instanceof GuardsCheckEnd){
    if (!event.shouldActivate){
      if (this.guardService.get('firstGuard')) {
        // do stuff
      }
    }
  }
});

Since we're using`@ngrx/store`, I'm checking a value there. Which is pretty close to this proposed solution. — AvailableName, Dec 16 '20 at 13:32

Which Guard fired GuardsCheckEnd?

1 Answers1