ngrx effect throws "dispatched an invalid action: undefined"

Question

I have this effect for logout confirmation under the condition of a dialog response, but am getting the following errors:

ERROR Error: Effect "AuthEffects.logoutConfirmation$" dispatched an invalid action: undefined

and

ERROR TypeError: Actions must be objects

heres the effect:

@Effect()
logoutConfirmation$ = this.actions$
    .ofType<Logout>(AuthActionTypes.Logout)
    .pipe(
      map(action => {
        if (action.confirmationDialog) {
          this.dialogService
            .open(LogoutPromptComponent)
            .afterClosed()
            .pipe(
              map(confirmed => {
                if (confirmed) {
                  return new LogoutConfirmed();
                } else {
                  return new LogoutCancelled();
                }
              })
            );
        } else {
          return new LogoutConfirmed();
        }
      })
    );

it works when confirmation dialog is activated, I guess it's something wrong with the map of the dialog's response, have been trying to understand it but couldn't fin a way. Any one has a clue on this?

Answer 1

Your outer map should be a mergeMap, as you are mapping the action to a new stream (in case that the condition is true).

You can fix this as follows:

import { of } from 'rxjs';
import {map, mergeMap } from 'rxjs/operators';

@Effect()
logoutConfirmation$: Observable<Action> = this.actions$
    .ofType<Logout>(AuthActionTypes.Logout)
    .pipe(
      mergeMap(action => {
        if (action.confirmationDialog) {
          return this.dialogService
            .open(LogoutPromptComponent)
            .afterClosed()
            .pipe(
              map(confirmed => confirmed ? new LogoutConfirmed():new LogoutCancelled())
            );
        } else {
          return of(new LogoutConfirmed());
        }
      })
    );

As a side note, always declare the explicit type of your effects in order to get errors at compile instead of run time.