Merge events in rxjs (Nestjs - saga cqrs)

Question

I am using cqrs with nestjs

I have a saga, that basically its rxjs implementations

@Saga()
updateEvent = (events$: Observable<any>): Observable<ICommand> => {
    return events$.pipe(
      ofType(UpdatedEvent,),
      map((event) => {
        return new otherCommand(event);
      })
    );
  };
}

the question is How can I merge Events that all extend the same class So I want only 1 saga to catch all events instead of saga per event

I tried

ofType(UpdatedEvent,CreateEvent,DeleteEvent),

but it does not work and typescript does not allow that , and also because of the generic type i got this :

right-hand side of 'instanceof' is not callable

my events is like:

class UpdateEvent extends Base<UpdateDto>{
   constructor(){super()}
}
class CreateEvent extends Base<CreateDto>{
   constructor(){super()}
}

there are differences between the events is the Dtos

Answer 1

Instead of using ofType you could just use filter(x => x instanceof UpdatedEvent || x instanceof CreateEvent || x instanceof DeleteEvent)

If this is a pattern you use often you could easily write a utility function eg instanceOneOf that takes a bunch of values in an array and does the instanceof checks internally.

Then you could do something like filter(x => instanceOneOf([UpdatedEvent, CreateEvent, DeleteEvent], x))