Asking this question for understanding: I have this code:
export class TpaEditGuard implements CanDeactivate<ResultContainerComponent> {
public editMode: boolean;
public bsModalRef: BsModalRef;
constructor(
private injector: Injector,
private modalService: BsModalService
) { }
public canDeactivate(
target: ResultContainerComponent,
currentRoute: ActivatedRouteSnapshot,
currentState: RouterStateSnapshot,
nextState: RouterStateSnapshot): Observable<boolean> | boolean {
target.hasChanges().subscribe((value) => {
this.editMode = value;
});
if (this.editMode) {
let subject = new Subject<any>();
this.bsModalRef = this.modalService.show(NavigateConfirmComponent,
{ animated: true, keyboard: false, backdrop: false, ignoreBackdropClick: true }
);
this.bsModalRef.content.navEvent = subject;
return this.bsModalRef.content.shouldNavigate();
} else {
return true;
}
}
Now, the if(this.editMode... is after and outside of the .subscribe. According to synchronous flow, the if should be evaluated before the value of this.editmode gets asynchronously set and evaluate to false. But the code works! Both ways. The if evaluates to true if I am sending an observable of true from hasChanges asynchronously and the dialog box appears! I am not setting this.editMode to true anywhere earlier. How does this work? In any other situation if we had a subscription and synchronous code using a value from the subscription outside we would not have got it. For example this:
this.someService.getData().subscribe(data => this.source = data)
console.log(this.source)
Here, the value of this.source printed would not have been the value of data from the db/back-end/resource call. It would have printed undefined or whatever was set earlier. How does that asynchrony work synchronously in canDeactivate then?
A reasoning seems to have been provided in this question here when the questioner says "Since the value this.savingState in the guard is always subscribed I don't think there is an issue with the conditional goes below.". But I don't get that. What is always subscribed? What, then, is not always subscribed? Or, what are we doing special to make it always subscribed? Again, my question how is this different from the getData example?
